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Are primes brighter and sharper than wide open zooms

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Anonymous
September 28, 2005 11:33:55 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Hi,

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?

- Siddhartha
Anonymous
September 28, 2005 12:15:55 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

The prime may be slightly brighter than the zoom, something which may
be more important in the motion-picture industry
They use a term called the "t stop" of a lens and it is a measure of
the light loss through a lens.
<http://artsci-ccwin.concordia.ca/comm/lighting.htm&gt;
The difference could be as little as a third or as great as (or greater
than) a 2 stop difference between what the f-stop is and the t-stop,
while the DoF will be the same and sharpnes is likely to be less with a
zoom than a prime.
In real life still photography I don't believe it would be noticable
(the difference in brightness), because of a variety of factors.
I personally would not lose any sleep over it.
Anonymous
September 28, 2005 12:55:35 PM

Archived from groups: rec.photo.digital (More info?)

Krystian Polak wrote:
> > Yes, more light will be transmitted through the lens with fewe elements
> > (everything else being equal).
>
> How much light will pure glass stop that not having extra one or two will
> change exposure about a fstop and you can notice diference? ;-)
>

Although my understanding of lens construction is limited but I believe
not all lenses are all glass. They use different material in a lens
alongwith some glass elements to keep the weight lower than an all
glass lens.

And as David Littlewood explains so lucidly below in his post, there
are factors other than an individual glass element's transmittance
that can effect the total transmittance of a lens.

- Siddhartha
Anonymous
September 28, 2005 1:25:13 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Nostrobino wrote:
> Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
> "prime."
>
> A prime lens is the camera lens as distinct from some other lens or
> lenticular device (close-up lens, tele converter, etc.) used with it. It has
> meant that since long before zoom lenses became commonplace, and therefore
> no need to use another term to mean "non-zoom."
>
> "Prime" is properly used in the sense of primary, main, chief or
> original--all dictionary definitions for "prime."
>
> There is NO dictionary definition for "prime" which means fixed focal length
> or single focal length, or fixed or single anything else.
>
> It would be nice if this nonsensical misusage, which obviously is based on
> someone's misunderstanding of the term some years ago (and then spread like
> cancer through the power of the Internet) could be stamped out. Surely "FFL"
> is at least as easy to type as "prime" anyway, and there never was any
> reason other than shortness to replace "fixed focal length" with the
> incorrect term.

I am aware of the mis-usage of the term *prime* and so guilty of
propogating the mis-usage but I feel its time the FFL camp realised
that there is no turning back.

- Siddhartha
Anonymous
September 28, 2005 2:48:02 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

On 28 Sep 2005 07:33:55 -0700, "Siddhartha Jain"
<reach.siddhartha@gmail.com> wrote:

>Hi,
>
>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>28-75mm) and both with an aperture of f2.8 -
>- Will the prime be brighter than the zoom because it has fewer lens
>elements?
>- Will the prime be sharper wide open than the zoom at 28mm?
>
>Ofcourse, a lot will depend on the particular makes and models being
>compared but is there a rule of thumb?

Rule of Thumb: A prime at any focal length and wide open is better
than a zoom at any focal length wide open.


********************************************************

"In general, the art of government consists in taking as
much money as possible from one party of the citizens
to give to the other."

Voltaire (1764)
Anonymous
September 28, 2005 3:57:22 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime."

A prime lens is the camera lens as distinct from some other lens or
lenticular device (close-up lens, tele converter, etc.) used with it. It has
meant that since long before zoom lenses became commonplace, and therefore
no need to use another term to mean "non-zoom."

"Prime" is properly used in the sense of primary, main, chief or
original--all dictionary definitions for "prime."

There is NO dictionary definition for "prime" which means fixed focal length
or single focal length, or fixed or single anything else.

It would be nice if this nonsensical misusage, which obviously is based on
someone's misunderstanding of the term some years ago (and then spread like
cancer through the power of the Internet) could be stamped out. Surely "FFL"
is at least as easy to type as "prime" anyway, and there never was any
reason other than shortness to replace "fixed focal length" with the
incorrect term.

N.
Anonymous
September 28, 2005 5:07:25 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

"Nostrobino" <not@home.today> wrote in message
news:ncGdnbEIlZv_IKfeRVn-qQ@comcast.com...
> Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
> "prime."
>
> A prime lens is the camera lens as distinct from some other lens or
> lenticular device (close-up lens, tele converter, etc.) used with it. It
> has meant that since long before zoom lenses became commonplace, and
> therefore no need to use another term to mean "non-zoom."
>
> "Prime" is properly used in the sense of primary, main, chief or
> original--all dictionary definitions for "prime."
>
> There is NO dictionary definition for "prime" which means fixed focal
> length or single focal length, or fixed or single anything else.
>
> It would be nice if this nonsensical misusage, which obviously is based on
> someone's misunderstanding of the term some years ago (and then spread
> like cancer through the power of the Internet) could be stamped out.
> Surely "FFL" is at least as easy to type as "prime" anyway, and there
> never was any reason other than shortness to replace "fixed focal length"
> with the incorrect term.
>
> N.
>

Many now accepted meanings of words have been created through misusage.
Perhaps you would prefer a dead language to English?

Eric Miller
Anonymous
September 28, 2005 5:35:29 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

"Siddhartha Jain" <reach.siddhartha@gmail.com> wrote in message
news:1127924713.491825.16030@g49g2000cwa.googlegroups.com...
> Nostrobino wrote:
>> Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
>> "prime."
>>
>> A prime lens is the camera lens as distinct from some other lens or
>> lenticular device (close-up lens, tele converter, etc.) used with it. It
>> has
>> meant that since long before zoom lenses became commonplace, and
>> therefore
>> no need to use another term to mean "non-zoom."
>>
>> "Prime" is properly used in the sense of primary, main, chief or
>> original--all dictionary definitions for "prime."
>>
>> There is NO dictionary definition for "prime" which means fixed focal
>> length
>> or single focal length, or fixed or single anything else.
>>
>> It would be nice if this nonsensical misusage, which obviously is based
>> on
>> someone's misunderstanding of the term some years ago (and then spread
>> like
>> cancer through the power of the Internet) could be stamped out. Surely
>> "FFL"
>> is at least as easy to type as "prime" anyway, and there never was any
>> reason other than shortness to replace "fixed focal length" with the
>> incorrect term.
>
> I am aware of the mis-usage of the term *prime* and so guilty of
> propogating the mis-usage but I feel its time the FFL camp realised
> that there is no turning back.

Well, not necessarily, though of course the more people who misuse the term,
the harder it will be to correct it.

Most people do not want to use wrong terminology since it makes them look
ignorant. In the case of "prime" being used to mean FFL, this has only
spread because readers who have not seen the term before, and then see it
used by people they assume are knowledgeable, naturally adopt it themselves.
Thus newbies are caught up in the misusage and (perhaps partly because they
feel using jargon will make them look knowledgeable too), contribute to the
spread.

Some will continue to use it anyway, but others will drop it (and some have
dropped it) when the error is pointed out to them.

N.
Anonymous
September 28, 2005 6:07:42 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

"Siddhartha Jain" <reach.siddhartha@gmail.com> wrote:

>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>28-75mm) and both with an aperture of f2.8 -
>- Will the prime be brighter than the zoom because it has fewer lens
>elements?
>- Will the prime be sharper wide open than the zoom at 28mm?
>
>Ofcourse, a lot will depend on the particular makes and models being
>compared but is there a rule of thumb?

The rule of thumb is that it depends on the make and model.


--
Mark Roberts
Photography and writing
www.robertstech.com
Anonymous
September 28, 2005 7:01:51 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Siddhartha Jain wrote:
> Hi,
>
> Given two lenses, one a prime (say 28mm) and the other a zoom (say
> 28-75mm) and both with an aperture of f2.8 -
> - Will the prime be brighter than the zoom because it has fewer lens
> elements?
> - Will the prime be sharper wide open than the zoom at 28mm?
>
> Ofcourse, a lot will depend on the particular makes and models being
> compared but is there a rule of thumb?
>
> - Siddhartha

In a word NO. At least it is no if you are talking about real life
situations.

However ---- In general primes will be sharper unless the zoom is a
much better quality lens. Of course that is possible and a really good zoom
can outperform a poor prime any day.

--
Joseph Meehan

Dia duit
Anonymous
September 28, 2005 7:05:57 PM

Archived from groups: rec.photo.digital (More info?)

"Siddhartha Jain" <reach.siddhartha@gmail.com> wrote in message
news:1127918035.410858.50240@o13g2000cwo.googlegroups.com...
> Hi,
>
> Given two lenses, one a prime (say 28mm) and the other a zoom (say
> 28-75mm) and both with an aperture of f2.8 -
> - Will the prime be brighter than the zoom because it has fewer lens
> elements?

Yes, more light will be transmitted through the lens with fewe elements
(everything else being equal).

> - Will the prime be sharper wide open than the zoom at 28mm?

It would probably be, yes, as the optical design makes fewer compromises
(but having fewer elements gives the optical designer less room to
manouever).

> Ofcourse, a lot will depend on the particular makes and models being
> compared but is there a rule of thumb?
>
> - Siddhartha

Oh, as in, a really good zoom may be better than a cheap and nasty prime?

David
Anonymous
September 28, 2005 7:15:42 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

A good prime should be sharper and exhibit fewer optical aberrations
compared to a zoom, with the aperture set wide open. Stopping the zoom down
should improve sharpness, but then you may lose the desirable effect of
limited depth of field, if that's what you wanted. Zooms typically have
different geometric distortion throughout the zoom range, usually barrell at
the wide end and pincushion at the tele end, being neutral somewhere in the
middle. A good prime should be able to combine better sharpness, contrast
and distortion characteristics compared to a zoom.

But there are some outstanding zooms out there these days and the advantage
of primes has been lessened as a result.

As the apertures are the same, there should be no difference in brightness.
The glass doesn't lose enough light in the way you fear to be a major
factor.

Ian

Digital Photography Now
http://dpnow.com
Visit our discussion forum at http://dpnow.com/Forums.html


"Siddhartha Jain" <reach.siddhartha@gmail.com> wrote in message
news:1127918035.410858.50240@o13g2000cwo.googlegroups.com...
> Hi,
>
> Given two lenses, one a prime (say 28mm) and the other a zoom (say
> 28-75mm) and both with an aperture of f2.8 -
> - Will the prime be brighter than the zoom because it has fewer lens
> elements?
> - Will the prime be sharper wide open than the zoom at 28mm?
>
> Ofcourse, a lot will depend on the particular makes and models being
> compared but is there a rule of thumb?
>
> - Siddhartha
>
September 28, 2005 8:21:26 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

"I would very much like to hear which particular lenses for DSLRs or
35mm SLRs produce a 2 stop reduction in illumination from that
expected at any given aperture."

2 stops is an awful lot, although I suppose some ancient zoom lenses
with lousy coatings might be that bad. One of the most complex zooms
I'm personally familiar with has about 40 elements, but nevertheless
suffers less than a 1-stop illumination reduction.

Brian
Anonymous
September 28, 2005 8:26:00 PM

Archived from groups: rec.photo.digital (More info?)

Yes, some elements can be made of exotic plastics and even other materials,
like fluorite. Indeed there have been discussions about glass lenses bonded
to plastic ones and the potential problem of different rates of expansion
and contraction in extremes of temperature...

Ian

Digital Photography Now
http://dpnow.com
Visit our discussion forum at http://dpnow.com/Forums.html



"Siddhartha Jain" <reach.siddhartha@gmail.com> wrote in message
news:1127922935.612832.134600@g49g2000cwa.googlegroups.com...
> Krystian Polak wrote:
>> > Yes, more light will be transmitted through the lens with fewe elements
>> > (everything else being equal).
>>
>> How much light will pure glass stop that not having extra one or two will
>> change exposure about a fstop and you can notice diference? ;-)
>>
>
> Although my understanding of lens construction is limited but I believe
> not all lenses are all glass. They use different material in a lens
> alongwith some glass elements to keep the weight lower than an all
> glass lens.
>
> And as David Littlewood explains so lucidly below in his post, there
> are factors other than an individual glass element's transmittance
> that can effect the total transmittance of a lens.
>
> - Siddhartha
>
Anonymous
September 28, 2005 8:42:20 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

In article <1127918035.410858.50240@o13g2000cwo.googlegroups.com>,
Siddhartha Jain <reach.siddhartha@gmail.com> writes
>Hi,
>
>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>28-75mm) and both with an aperture of f2.8 -
>- Will the prime be brighter than the zoom because it has fewer lens
>elements?
>- Will the prime be sharper wide open than the zoom at 28mm?
>
>Ofcourse, a lot will depend on the particular makes and models being
>compared but is there a rule of thumb?
>
>- Siddhartha
>
Other things being equal, yes to both, though with well-designed modern
lenses the difference may be small.

Brightness:

The conventional f-stop designation of aperture is a purely geometric
measure and takes no account of the actual transmission properties of
the lens. In reality, not all of the light going into a lens will come
out at the other end, and some of the light that does come out will be
scattered, and hence will reduce image quality.

Attenuation takes two forms: absorption and reflection/scattering.
Absorption is purely proportional to the depth of glass; a typical
figure for normal optical glass would be 10% for a total glass path
length of 100mm. Most photographic lenses would fall far short of this,
though some big lenses may get there. This attenuation is entirely
proportional to the length of the light path through glass; thus a zoom
with 12-15 elements is likely to experience more absorption than a fixed
focal length lens with 5-10 elements.

The other form is reflection from glass-air interfaces. This is
unavoidable, but can be reduced very greatly by coating. The percentage
of reflection depends on the refractive index of the glass, but for
typical n=1.50 optical glass (uncoated) the percentage is about 4%.
This, remember, is at each glass air interface, two per lens element.
Thus a compound lens with 15 elements will have 30 interfaces, and will
only transmit (0.96)^30 or about 20% of the light. (In fact another
20-40% will get to the film or sensor as scattered light - giving an
image of appallingly bad contrast). A single layer coating will reduce
the reflection to about 1-1.5%, and modern multi-coating reduces it to
around 0.3-0.5%.

This still gives a transmission factor of about 83.5% for a 20-surface
(10-element) system, against 91.4% for a 10-surface (5-element) system.

Resolution:

There is not the same direct relationship between complexity and
resolution as that above between complexity and transmission. However,
the compromises required to balance zoom ratio, overall size, mechanical
complexity and cost at the same time as controlling the seven distinct
varieties of lens aberrations mean that in almost every case the zoom
lens will have lower resolution than the fixed focal length lens of
similar quality of design and manufacture. You can see this from the MTF
function curves published by most lens manufacturers. Having just
checked some of these myself to answer your question, I am actually
quite impressed by how small these differences are; a couple of decades
ago the differences would have been much greater. (Be aware when
comparing MTF curves that they usually show wide open and f/8 data; as a
zoom will usually have a smaller maximum aperture than the comparable
fixed focal length lenses, you should avoid comparing these - best look
at the f/8 curves for a fair comparison.)

David
--
David Littlewood
Anonymous
September 28, 2005 8:42:21 PM

Archived from groups: rec.photo.digital (More info?)

"David Littlewood" <david@nospam.demon.co.uk> wrote in message
news:IPL49cCcnrODFwX4@dlittlewood.co.uk...
> In article <1127918035.410858.50240@o13g2000cwo.googlegroups.com>,
> Siddhartha Jain <reach.siddhartha@gmail.com> writes
>>Hi,
>>
>>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>>28-75mm) and both with an aperture of f2.8 -
>>- Will the prime be brighter than the zoom because it has fewer lens
>>elements?
>>- Will the prime be sharper wide open than the zoom at 28mm?
>>
>>Ofcourse, a lot will depend on the particular makes and models being
>>compared but is there a rule of thumb?
>>
>>- Siddhartha
>>
> Other things being equal, yes to both, though with well-designed modern
> lenses the difference may be small.
>
> Brightness:
>
> The conventional f-stop designation of aperture is a purely geometric
> measure and takes no account of the actual transmission properties of the
> lens. In reality, not all of the light going into a lens will come out at
> the other end, and some of the light that does come out will be scattered,
> and hence will reduce image quality.
>
> Attenuation takes two forms: absorption and reflection/scattering.
> Absorption is purely proportional to the depth of glass; a typical figure
> for normal optical glass would be 10% for a total glass path length of
> 100mm. Most photographic lenses would fall far short of this, though some
> big lenses may get there. This attenuation is entirely proportional to the
> length of the light path through glass; thus a zoom with 12-15 elements is
> likely to experience more absorption than a fixed focal length lens with
> 5-10 elements.
>
> The other form is reflection from glass-air interfaces. This is
> unavoidable, but can be reduced very greatly by coating. The percentage of
> reflection depends on the refractive index of the glass, but for typical
> n=1.50 optical glass (uncoated) the percentage is about 4%. This,
> remember, is at each glass air interface, two per lens element. Thus a
> compound lens with 15 elements will have 30 interfaces, and will only
> transmit (0.96)^30 or about 20% of the light. (In fact another 20-40% will
> get to the film or sensor as scattered light - giving an image of
> appallingly bad contrast). A single layer coating will reduce the
> reflection to about 1-1.5%, and modern multi-coating reduces it to around
> 0.3-0.5%.
>
> This still gives a transmission factor of about 83.5% for a 20-surface
> (10-element) system, against 91.4% for a 10-surface (5-element) system.
>
> Resolution:
>
> There is not the same direct relationship between complexity and
> resolution as that above between complexity and transmission. However, the
> compromises required to balance zoom ratio, overall size, mechanical
> complexity and cost at the same time as controlling the seven distinct
> varieties of lens aberrations mean that in almost every case the zoom lens
> will have lower resolution than the fixed focal length lens of similar
> quality of design and manufacture. You can see this from the MTF function
> curves published by most lens manufacturers. Having just checked some of
> these myself to answer your question, I am actually quite impressed by how
> small these differences are; a couple of decades ago the differences would
> have been much greater. (Be aware when comparing MTF curves that they
> usually show wide open and f/8 data; as a zoom will usually have a smaller
> maximum aperture than the comparable fixed focal length lenses, you should
> avoid comparing these - best look at the f/8 curves for a fair
> comparison.)
>
> David
> --
> David Littlewood

Good information. In virtually any lens, many of the elements are cemented
together into groups. There is typically much less glass to air boundaries
than 2x the element count. At the cemented boundaries, the reflection loss
is much lower than glass to air loss, even with coatings.
-S
September 28, 2005 10:52:01 PM

Archived from groups: rec.photo.digital (More info?)

On Wed, 28 Sep 2005 16:26:00 GMT, "Digital Photography Now"
<infoplsremove@this-dpnow.com> wrote:

>Yes, some elements can be made of exotic plastics and even other materials,
>like fluorite. Indeed there have been discussions about glass lenses bonded
>to plastic ones and the potential problem of different rates of expansion
>and contraction in extremes of temperature...

You also have to deal with the kind of coatings on each lens surface,
and the angles of the lens surfaces as this effects the reflectance at
each surface. All together they add up to contrast loss, loss of light
throughput. Total loss with old mag-fluoride coated zoom lenses with
12 elements or so could be on the order of 40% or more (1.5% loss per
surface. Nowadays, with better quality multicoatings, the loss is
less but still considerable.
-Rich
>
>Ian
>
>Digital Photography Now
>http://dpnow.com
>Visit our discussion forum at http://dpnow.com/Forums.html
>
>
>
>"Siddhartha Jain" <reach.siddhartha@gmail.com> wrote in message
>news:1127922935.612832.134600@g49g2000cwa.googlegroups.com...
>> Krystian Polak wrote:
>>> > Yes, more light will be transmitted through the lens with fewe elements
>>> > (everything else being equal).
>>>
>>> How much light will pure glass stop that not having extra one or two will
>>> change exposure about a fstop and you can notice diference? ;-)
>>>
>>
>> Although my understanding of lens construction is limited but I believe
>> not all lenses are all glass. They use different material in a lens
>> alongwith some glass elements to keep the weight lower than an all
>> glass lens.
>>
>> And as David Littlewood explains so lucidly below in his post, there
>> are factors other than an individual glass element's transmittance
>> that can effect the total transmittance of a lens.
>>
>> - Siddhartha
>>
>
Anonymous
September 28, 2005 10:56:26 PM

Archived from groups: rec.photo.digital (More info?)

In article <433ac0ad$1_2@newsfeed.slurp.net>, SimonLW <nospam@donet.com>
writes
>
>"David Littlewood" <david@nospam.demon.co.uk> wrote in message
>news:IPL49cCcnrODFwX4@dlittlewood.co.uk...

[snip]
>
>Good information. In virtually any lens, many of the elements are cemented
>together into groups. There is typically much less glass to air boundaries
>than 2x the element count. At the cemented boundaries, the reflection loss
>is much lower than glass to air loss, even with coatings.
>-S
>
True; the explanation was however already getting rather long....

As you suggest, you should look at the number of groups rather than the
number of elements.

In practice, the number of cemented pairs in any lens is usually much
smaller than half the number of elements. 1 or 2 pairs is common in
fixed focal length lenses (and quite a few have none). Zooms on average
have a couple more - but even here, some have none (e.g. the EOS 28-80
f/3.5-5.6II and 35-80 f/4-5.6 III both have 10 elements in 10 groups).

David
--
David Littlewood
September 28, 2005 10:57:32 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

"Siddhartha Jain" <reach.siddhartha@gmail.com> wrote in message
news:1127918035.410858.50240@o13g2000cwo.googlegroups.com...
> Hi,
>
> Given two lenses, one a prime (say 28mm) and the other a zoom (say
> 28-75mm) and both with an aperture of f2.8 -
> - Will the prime be brighter than the zoom because it has fewer lens
> elements?
> - Will the prime be sharper wide open than the zoom at 28mm?
>
> Ofcourse, a lot will depend on the particular makes and models being
> compared but is there a rule of thumb?
>
> - Siddhartha
>

In theory, zooms will always be somewhat below the quality of prime lenses.
Zooms typically have barrel distortion at one end of the zoom range, and
pincushion distortion at the other. Older zooms, especially those that did
not have decent multicoating, were more prone to flare and ghosting, because
of the light bouncing back and forth off the air-to-glass surfaces.

The margin of superiority of primes over zooms has narrowed, and many
photographers find the convenience and economy of one zoom versus several
primes to be more important than some slight degree of image degradation. I
have a couple of Pentax zooms in K-mount that do a credible job, and it
certainly is easier to carry two zooms than it is to carry 5 or 6 primes.
Thirty years ago, I bought a couple of third-party zooms for my M43 bodies,
and the results were just awful, relative to my SMC Takumar prime lens.
Colors had a grayish cast, saturation was less than on the OEM lens, the
aperture ring was operated in the reverse direction of my Takumar's (Pentax
does it "backwards"), the front element turned when the focusing ring was
moved, making polarizer use difficult, the lens front element was not the
standard Takumar 49mm or 58mm, making it necessary to buy filters just for
use in that lens, and the resolution was noticeably less than that of the
OEM Takumar.

The build quality was obviously less-good than the OEM lens. The focusing
was not nearly as smooth, the zoom ring was a bit on the tight side, the
lens barrel was not as sturdy and the lens lacked multicoating (this was 30
years ago). So, while I saved a few dollars, I got pretty much what I paid
for and no more. I ended up putting that zoom lens up on the shelf, where
it remains to this day, and I bought only OEM lenses after that. They cost
a bit more, but the level of satisfaction that I derived from them made up
for the higher price. And not a single one of the OEM lenses has failed, in
3 decades.

British landscape photographer and author Brian Bower noted that, while his
Leica R zoom lenses cost a lot more than non-OEM lenses, he felt that they
were a good value because they retained their accuracy after over a decade
of hard use. He noted in one of his books that the cheaper zoom lenses
might see the elements go out of precise adjustment and the zoom mechanism
might become very loose after a time, making it necessary to keep checking
the zoom ring to be certain that the zoom ratio has not changed from
whatever it was originally set to. Bower valued consistently good results
more than lower price. He made his living with those tools, and he had
little tolerance for lens failures.

My own take on it is that if the proposed use of the lens is of a very
casual nature, it is probably okay to go for the savings. But if top
performance and reliability are paramount, one really has to think about
whether the savings might be offset by potential future loss from
poorly-performing equipment. I would rather have only a couple of really
good lenses than a kit full of lenses of questionable reliability and
performance. It seems that, in my own case, virtually every time I have
tried to save money by cutting corners I ended up paying double.
Anonymous
September 28, 2005 11:20:22 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

In article <1127918035.410858.50240@o13g2000cwo.googlegroups.com>,
Siddhartha Jain <reach.siddhartha@gmail.com> wrote:

> Given two lenses, one a prime (say 28mm) and the other a zoom (say
> 28-75mm) and both with an aperture of f2.8 -
> - Will the prime be brighter than the zoom because it has fewer lens
> elements?
> - Will the prime be sharper wide open than the zoom at 28mm?
>
> Ofcourse, a lot will depend on the particular makes and models being
> compared but is there a rule of thumb?

F/2.8 lets the same amount of light through regardless of the lens
design. F/2.8 is f/2.8.

Being from the old school, I would expect a fixed focal length lens to
be sharper than a zoom, but you may have to go to laboratory conditions
to prove it.
September 29, 2005 12:56:27 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Eugene wrote:
> Just some links you may want to check out...
>
> http://photonotes.org/cgi-bin/entry.pl?id=Primelens
> http://en.wikipedia.org/wiki/Prime_lens
> http://www.absoluteastronomy.com/encyclopedia/p/pr/prim...
>
> Please stop spreading misinformation. The first usage of a term is not
> necessarily the correct one.

No, but it can be good to distinguish between slang terminology
and standard terminology.

For instance, in audio people often talk about "acetate masters"
when they mean "lacquer originals." The slang terminology is
wrong on two counts because the originals of disc recordings
are made on cellulose nitrate lacquer and never acetate and they
are originals, not masters, according to long established terminology.
The use of the slang "acetate master" has caused very little real
confusion over the 70 years in which it has been in common use,
but it is still not correct because the disc is neither made
of acetate nor a master. (Wikipedia gets the definition of
"master recording" wrong, so I don't think it is a very good
source for standard technical vocabulary.)

An example in photography is the use of the word "macro"
as a synonym for "extreme close-up." Photomacrography,
from which we get "macro," has a very well established
technical meaning requiring the image size to be equal to
or larger than the object size. The Wikipedia article
"Macro Photography" starts out with the standard definition
which it calls the "classical definition" and then goes
on to discuss the extended use of the term in photographers'
slang without being particularly clear that the extended
meaning is still non-standard terminology. BTW it is better
to use "photomacrography" than "macro photography" since
"macrophotography" can mean the making of large photographs
by analogy with the difference between "photomicrography"
and "microphotography" which should never be confused with
each other.

The use of "prime lens" for "fixed focal length lens" appears
to originate in cinema where the need for a handy term
for a non-zoom lens was felt long before such a term was
needed in still photography. As a handy bit of slang, it
has much to recommend it: it is easy to say and quickly
understood. As a technical term, it has two major difficulties:
the word "prime" has little connection to what is meant,
and there was a prior use of the term in which the word
"prime" actually made sense.


> If you start referring to zooms as "prime" you're just going
> to make yourself sound stupid.

No, because you would always also be using an additional term
such as "supplementary lens" or "teleconverter" which would
supply the context which would make the meaning clear.


> Whatever you think it meant originally, is not what it means now.

You know, sometimes words have two meanings.

Most of us can live with slang terminology and standard technical
terminology without getting particularly confused. Slang terminology
can be very handy: I'm not going to stop saying "Hypo" when I know
that fixer is actually thiosulphate. It isn't very likely that someone
will think I mean the actual chemical "sodium hyposulphite" AKA
"sodium hydrosulphite" which is AFAIK not used in photography.
But it is still good to distinguish between slang and proper technical
language. If I ordered "sodium hyposulphite" from a chemical supplier
who served dyers it is just possible I might get the wrong chemical.

Peter.
--
pirwin@ktb.net
September 29, 2005 1:01:50 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Eugene wrote:
> Just some links you may want to check out...
>
> http://photonotes.org/cgi-bin/entry.pl?id=Primelens
> http://en.wikipedia.org/wiki/Prime_lens
> http://www.absoluteastronomy.com/encyclopedia/p/pr/prim...
>
> Please stop spreading misinformation. The first usage of a term is not
> necessarily the correct one.

No, but it can be good to distinguish between slang terminology
and standard terminology.

For instance, in audio people often talk about "acetate masters"
when they mean "lacquer originals." The slang terminology is
wrong on two counts because the originals of disc recordings
are made on cellulose nitrate lacquer and never acetate and they
are originals, not masters, according to long established terminology.
The use of the slang "acetate master" has caused very little real
confusion over the 70 years in which it has been in common use,
but it is still not correct because the disc is neither made
of acetate nor a master. (Wikipedia gets the definition of
"master recording" wrong, so I don't think it is a very good
source for standard technical vocabulary.)

An example in photography is the use of the word "macro"
as a synonym for "extreme close-up." Photomacrography,
from which we get "macro," has a very well established
technical meaning requiring the image size to be equal to
or larger than the object size. The Wikipedia article
"Macro Photography" starts out with the standard definition
which it calls the "classical definition" and then goes
on to discuss the extended use of the term in photographers'
slang without being particularly clear that the extended
meaning is still non-standard terminology. BTW it is better
to use "photomacrography" than "macro photography" since
"macrophotography" can mean the making of large photographs
by analogy with the difference between "photomicrography"
and "microphotography" which should never be confused with
each other.

The use of "prime lens" for "fixed focal length lens" appears
to originate in cinema where the need for a handy term
for a non-zoom lens was felt long before such a term was
needed in still photography. As a handy bit of slang, it
has much to recommend it: it is easy to say and quickly
understood. As a technical term, it has two major difficulties:
the word "prime" has little connection to what is meant,
and there was a prior use of the term in which the word
"prime" actually made sense.


> If you start referring to zooms as "prime" you're just going
> to make yourself sound stupid.

No, because you would always also be using an additional term
such as "supplementary lens" or "teleconverter" which would
supply the context which would make the meaning clear.


> Whatever you think it meant originally, is not what it means now.

You know, sometimes words have two meanings.

Most of us can live with slang terminology and standard technical
terminology without getting particularly confused. Slang terminology
can be very handy: I'm not going to stop saying "Hypo" when I know
that fixer is actually thiosulphate. It isn't very likely that someone
will think I mean the actual chemical "sodium hyposulphite" AKA
"sodium hydrosulphite" which is AFAIK not used in photography.
But it is still good to distinguish between slang and proper technical
language. If I ordered "sodium hyposulphite" from a chemical supplier
who served dyers it is just possible I might get the wrong chemical.

Peter.
--
pirwin@ktb.net
Anonymous
September 29, 2005 1:47:15 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>28-75mm) and both with an aperture of f2.8 -
>- Will the prime be brighter than the zoom because it has fewer lens
>elements?

No. f/2.8 tells you exactly how bright the lens is. (It's almost
like the old question about a pound of lead and a pound of feathers -
they do both weigh the same.)

>- Will the prime be sharper wide open than the zoom at 28mm?

Probably, particuarly if both lenses are in the same price range. On
the other hand, there are lots of expensive zoom lenses that are
sharper than cheap fixed lenses.

-Joel

----------------------------------------------------------------------------
Free 35mm lens & digital camera reviews: http://www.exc.com/photography
----------------------------------------------------------------------------
Anonymous
September 29, 2005 1:49:34 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

dj_nme@hotmail.com wrote:

>The prime may be slightly brighter than the zoom, something which may
>be more important in the motion-picture industry
>They use a term called the "t stop" of a lens and it is a measure of
>the light loss through a lens.
><http://artsci-ccwin.concordia.ca/comm/lighting.htm&gt;
>The difference could be as little as a third or as great as (or greater
>than) a 2 stop difference between what the f-stop is and the t-stop,
>while the DoF will be the same and sharpnes is likely to be less with a
>zoom than a prime.

I would very much like to hear which particular lenses for DSLRs or
35mm SLRs produce a 2 stop reduction in illumination from that
expected at any given aperture.

You needn't list all of them, merely give some examples. ;-)

>In real life still photography I don't believe it would be noticable
>(the difference in brightness), because of a variety of factors.
>I personally would not lose any sleep over it.

You wouldn't lose any sleep over a *two stop* reduction in
illumination? Either you are a very sound sleeper, or that reduction
simply doesn't exist. Or possibly both.

;-)
Anonymous
September 29, 2005 1:52:41 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

"Nostrobino" <not@home.today> wrote:

>It would be nice if this nonsensical misusage, which obviously is based on
>someone's misunderstanding of the term some years ago (and then spread like
>cancer through the power of the Internet) could be stamped out.

The use, or misuse, of the term "prime" is nothing new. The same
discussion was around in the 1960s and 70s. It wasn't resolved then
and probably never will be.

So don't blame the Internet. Blame the manufacturers who chose to use
this term as a marketing tool at various times in the last 50 years.

;-)
Anonymous
September 29, 2005 2:19:42 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Peter wrote:

> You know, sometimes words have two meanings.
>
> Most of us can live with slang terminology and standard technical
> terminology without getting particularly confused. Slang terminology
> can be very handy: I'm not going to stop saying "Hypo" when I know
> that fixer is actually thiosulphate. It isn't very likely that someone

Not to be pedantic, but I think you mean "Jargon" not "Slang".
Anonymous
September 29, 2005 2:23:36 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Dr. Joel M. Hoffman wrote:

>>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>>28-75mm) and both with an aperture of f2.8 -
>>- Will the prime be brighter than the zoom because it has fewer lens
>>elements?
>
>
> No. f/2.8 tells you exactly how bright the lens is. (It's almost
> like the old question about a pound of lead and a pound of feathers -
> they do both weigh the same.)
>

Well, no. The F-stop is the ratio of the aperature to the focal length,
which is constant regardless of the actual material(s) of the glass. In
the extreme case of spraying black paint on the lens, you could have an
F:2.8 lens with 0% light transmission.
Anonymous
September 29, 2005 2:29:43 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Randall Ainsworth wrote:

> In article <1127918035.410858.50240@o13g2000cwo.googlegroups.com>,
> Siddhartha Jain <reach.siddhartha@gmail.com> wrote:
>
>
>>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>>28-75mm) and both with an aperture of f2.8 -
>>- Will the prime be brighter than the zoom because it has fewer lens
>>elements?
>>- Will the prime be sharper wide open than the zoom at 28mm?
>>
>>Ofcourse, a lot will depend on the particular makes and models being
>>compared but is there a rule of thumb?
>
>
> F/2.8 lets the same amount of light through regardless of the lens
> design. F/2.8 is f/2.8.
>

Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass,
you can grind it into a lens shape, but if you use it as an element in a
lens, you're going to get some reallllllly slow shutter speeds. Of
course that's an extreme case, the difference between plain old glass
glass, and exotic flouro-silicates is only a few fractions of a percent.
Anonymous
September 29, 2005 3:19:34 AM

Archived from groups: rec.photo.digital (More info?)

In article <GdE_e.2180$Ge5.2148@fe10.lga>, Dr. Joel M. Hoffman
<joel@exc.com> writes
>>> Yes, more light will be transmitted through the lens with fewe elements
>>> (everything else being equal).
>>
>>How much light will pure glass stop that not having extra one or two will
>>change exposure about a fstop and you can notice diference? ;-)
>
>You've missed the point. Any two lenses at exactly f/2.8 let in
>exactly the same amount of light.
>
>-Joel
>
No, I am afraid it is you who have missed the point. The f-number is a
geometric measurement - how wide is the effective aperture compared with
the focal length of the lens. It completely ignores all transmission
effects.

In the past, this was so important to the movie industry (for whom
consistency of brightness from scene to scene and cut to cut as shot on
different lenses was extremely important) used lenses calibrated in T
stops, which were in effect f-stops adjusted for transmission. Lenses
which had T-stops close to the f-stop values were apparently highly
prized as they gave a higher depth of field (which is an entirely
geometric affect) for a given T value.

Today the correction factor for a typical zoom lens in still photography
is probably about 1/3 of a stop (or about 20%), which is of course taken
care of by TTL metering. I don't know whether the movie business still
uses T-stops.

David
--
David Littlewood
Anonymous
September 29, 2005 5:32:11 AM

Archived from groups: rec.photo.digital (More info?)

> Yes, more light will be transmitted through the lens with fewe elements
> (everything else being equal).

How much light will pure glass stop that not having extra one or two will
change exposure about a fstop and you can notice diference? ;-)

Regards,

K.Polak
Anonymous
September 29, 2005 5:32:12 AM

Archived from groups: rec.photo.digital (More info?)

Krystian Polak wrote:
>> Yes, more light will be transmitted through the lens with fewe
>> elements (everything else being equal).
>
> How much light will pure glass stop that not having extra one or two
> will change exposure about a fstop and you can notice diference? ;-)
>
> Regards,
>
> K.Polak

We're talking a few percent, not whole f/stops. T/stop is a better
measure of light transmission than f/stop. I wouldn't be surprised if a
colour cast was the first effect to be noticed rather than the light loss
itself.

David
Anonymous
September 29, 2005 5:32:12 AM

Archived from groups: rec.photo.digital (More info?)

>> Yes, more light will be transmitted through the lens with fewe elements
>> (everything else being equal).
>
>How much light will pure glass stop that not having extra one or two will
>change exposure about a fstop and you can notice diference? ;-)

You've missed the point. Any two lenses at exactly f/2.8 let in
exactly the same amount of light.

-Joel

----------------------------------------------------------------------------
Free 35mm lens & digital camera reviews: http://www.exc.com/photography
----------------------------------------------------------------------------
Anonymous
September 29, 2005 5:32:13 AM

Archived from groups: rec.photo.digital (More info?)

In article <GdE_e.2180$Ge5.2148@fe10.lga>,
Dr. Joel M. Hoffman <joel@exc.com> wrote:
>>> Yes, more light will be transmitted through the lens with fewe elements
>>> (everything else being equal).
>>
>>How much light will pure glass stop that not having extra one or two will
>>change exposure about a fstop and you can notice diference? ;-)
>
>You've missed the point. Any two lenses at exactly f/2.8 let in
>exactly the same amount of light.

Not true. That's why t-stops exist.
Anonymous
September 29, 2005 8:05:19 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

kashe@sonic.net skrev:

> On Wed, 28 Sep 2005 22:29:43 -0700, "Brion K. Lienhart"
> <brionl@lienhart.name> wrote:

> F:2.8 is solely based on the size of the lens. Obsidian is glass,
> >you can grind it into a lens shape, but if you use it as an element in a
> >lens, you're going to get some reallllllly slow shutter speeds. Of
> >course that's an extreme case, the difference between plain old glass
> >glass, and exotic flouro-silicates is only a few fractions of a percent.
>
> So what was your point in bringing up a special case ulikely
> to be implemented?

To illustrate the difference in principle between f-stop and t-stop in
an obviuos way, perhaps?

Jan Böhme
Anonymous
September 29, 2005 9:44:02 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

In article <X4adnZDtAfRX5qbeRVn-rQ@comcast.com>, Brion K. Lienhart
<brionl@lienhart.name> wrote:

> Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass,
> you can grind it into a lens shape, but if you use it as an element in a
> lens, you're going to get some reallllllly slow shutter speeds. Of
> course that's an extreme case, the difference between plain old glass
> glass, and exotic flouro-silicates is only a few fractions of a percent.

An f/2.8 lens is going to allow a specific amount of light to go
through regardless of what kind of glass it's made of.
September 29, 2005 10:50:36 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Randall Ainsworth wrote:
> In article <X4adnZDtAfRX5qbeRVn-rQ@comcast.com>, Brion K. Lienhart
> <brionl@lienhart.name> wrote:
>
> > Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass,
> > you can grind it into a lens shape, but if you use it as an element in a
> > lens, you're going to get some reallllllly slow shutter speeds. Of
> > course that's an extreme case, the difference between plain old glass
> > glass, and exotic flouro-silicates is only a few fractions of a percent.
>
> An f/2.8 lens is going to allow a specific amount of light to go
> through regardless of what kind of glass it's made of.

Actually no, but in most cases the difference is unimportant.

One case where the difference generally is important is with
a mirror lens. A mirror lens is generally only about 60%
efficient compared with around 90%+ efficiency for a glass
lens with ten multicoated air-glass surfaces.

A 500mm f/6.3 mirror lens may let in about the same light
as a 500mm f/8 coated glass lens. This can be a significant
factor when deciding what lens to buy. A mirror lens does
not gather quite as much light as you would expect from
the aperture.

Peter.
--
pirwin@ktb.net
September 29, 2005 11:17:53 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Brion K. Lienhart wrote:
> Peter wrote:
>
> > You know, sometimes words have two meanings.
> >
> > Most of us can live with slang terminology and standard technical
> > terminology without getting particularly confused. Slang terminology
> > can be very handy: I'm not going to stop saying "Hypo" when I know
> > that fixer is actually thiosulphate. It isn't very likely that someone
>
> Not to be pedantic, but I think you mean "Jargon" not "Slang".


Actually you are being pedantic, saying "not to be pedantic"
in front of a sentence doesn't make it so.

I looked up "slang" and "jargon" in several dictionaries,
and at least some of the meanings are nearly interchangable.
I chose "slang" because I wanted to emphasize the non-standard
nature of the vocabulary rather than any lack of intelligibility
to outsiders.

Peter.
--
pirwin@ktb.net
Anonymous
September 29, 2005 11:46:16 AM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

"Randall Ainsworth" <rag@nospam.techline.com> wrote in message
news:290920050544028507%rag@nospam.techline.com...

> An f/2.8 lens is going to allow a specific amount of light to go
> through regardless of what kind of glass it's made of.

Strictly speaking you are on the wrong track. I think you may be confusing
transmission with focal ratio. F2.8 simply speaks to the focal
ratio.......slower materials would result in less light being transmitted.
Anonymous
September 29, 2005 12:03:37 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

"Siddhartha Jain" <reach.siddhartha@gmail.com> wrote in message
news:1127918035.410858.50240@o13g2000cwo.googlegroups.com...
> Hi,
>
> Given two lenses, one a prime (say 28mm) and the other a zoom (say
> 28-75mm) and both with an aperture of f2.8 -
> - Will the prime be brighter than the zoom because it has fewer lens
> elements?
> - Will the prime be sharper wide open than the zoom at 28mm?
>
> Ofcourse, a lot will depend on the particular makes and models being
> compared but is there a rule of thumb?
>
> - Siddhartha

I've heard it suggested that may high quality zooms are visually
indistinguishable from their prime equivalents - however both can usually
out-perform most photographers!
Anonymous
September 29, 2005 12:03:38 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

In message <rGC_e.14903$iM2.1224183@news.xtra.co.nz>,
"Cockpit Colin" <spam@nospam.com> wrote:

>I've heard it suggested that may high quality zooms are visually
>indistinguishable from their prime equivalents

You can always bring out the difference in a large print or display, or
with teleconverters or extension tubes

> - however both can usually
>out-perform most photographers!

Not under good conditions.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
September 29, 2005 1:24:43 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Yes, I'm sure the missuse of the term "prime lens" will go down in
history as one of the greatest tragedies of our generation ;-)

> Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
> "prime."
>
Anonymous
September 29, 2005 2:03:12 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

In article <290920050544028507%rag@nospam.techline.com>, Randall
Ainsworth <rag@nospam.techline.com> wrote:

> An f/2.8 lens is going to allow a specific amount of light to go
> through regardless of what kind of glass it's made of.

Ahem. Notice the previous 50+ responses in this thread? If not, read
some - you're dead wrong. What you're thinking of is a T-stop. Lenses
of the same mathematical aperture (f/stop) can and do wary widely in
transmission. Period.
September 29, 2005 2:09:35 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

You make it sound like it's some kind of disease. In the grand scheme of
things, does it really matter? Languages are dynamic, and the meanings
of words are constantly changing. The original meaning of "prime" in the
photographic sense is just an invention anyway. Referring to the
dictionary I find no mention of lenses as related to the meaning of the
word "prime". Who is therefore to decide which usage is correct? You
apparently!

The first listing that I found at dictionary.com is...

"First in excellence, quality, or value"

I think therefore it's perfectly reasonable to refer to a high quality
FFL lens in this way.

Perhaps you should just "chill out" a little and stop preaching about
who or who isn't ignorant.

>
> Well, not necessarily, though of course the more people who misuse the term,
> the harder it will be to correct it.
>
> Most people do not want to use wrong terminology since it makes them look
> ignorant. In the case of "prime" being used to mean FFL, this has only
> spread because readers who have not seen the term before, and then see it
> used by people they assume are knowledgeable, naturally adopt it themselves.
> Thus newbies are caught up in the misusage and (perhaps partly because they
> feel using jargon will make them look knowledgeable too), contribute to the
> spread.
>
> Some will continue to use it anyway, but others will drop it (and some have
> dropped it) when the error is pointed out to them.
>
> N.
>
>
Anonymous
September 29, 2005 2:09:36 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Eugene wrote:
> You make it sound like it's some kind of disease. In the grand scheme of
> things, does it really matter? Languages are dynamic, and the meanings
> of words are constantly changing. The original meaning of "prime" in the
> photographic sense is just an invention anyway. Referring to the
> dictionary I find no mention of lenses as related to the meaning of the
> word "prime". Who is therefore to decide which usage is correct? You
> apparently!

It's pretty much established jargon in the photo industry. I've seen it
used in this sense since the mid-70s (when I started paying attention to
photo stuff). I hardly think it can be blamed solely on the internet.
Anonymous
September 29, 2005 2:11:51 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

On Wed, 28 Sep 2005 22:29:43 -0700, "Brion K. Lienhart"
<brionl@lienhart.name> wrote:

>Randall Ainsworth wrote:
>
>> In article <1127918035.410858.50240@o13g2000cwo.googlegroups.com>,
>> Siddhartha Jain <reach.siddhartha@gmail.com> wrote:
>>
>>
>>>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>>>28-75mm) and both with an aperture of f2.8 -
>>>- Will the prime be brighter than the zoom because it has fewer lens
>>>elements?
>>>- Will the prime be sharper wide open than the zoom at 28mm?
>>>
>>>Ofcourse, a lot will depend on the particular makes and models being
>>>compared but is there a rule of thumb?
>>
>>
>> F/2.8 lets the same amount of light through regardless of the lens
>> design. F/2.8 is f/2.8.
>>
>
>Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass,
>you can grind it into a lens shape, but if you use it as an element in a
>lens, you're going to get some reallllllly slow shutter speeds. Of
>course that's an extreme case, the difference between plain old glass
>glass, and exotic flouro-silicates is only a few fractions of a percent.

So what was your point in bringing up a special case ulikely
to be implemented?
September 29, 2005 2:45:13 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Just some links you may want to check out...

http://photonotes.org/cgi-bin/entry.pl?id=Primelens
http://en.wikipedia.org/wiki/Prime_lens
http://www.absoluteastronomy.com/encyclopedia/p/pr/prim...

Please stop spreading misinformation. The first usage of a term is not
necessarily the correct one. If you start referring to zooms as "prime"
you're just going to make yourself sound stupid. Whatever you think it
meant originally, is not what it means now.

> Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
> "prime."
>
> A prime lens is the camera lens as distinct from some other lens or
> lenticular device (close-up lens, tele converter, etc.) used with it. It has
> meant that since long before zoom lenses became commonplace, and therefore
> no need to use another term to mean "non-zoom."
>
> "Prime" is properly used in the sense of primary, main, chief or
> original--all dictionary definitions for "prime."
>
> There is NO dictionary definition for "prime" which means fixed focal length
> or single focal length, or fixed or single anything else.
>
> It would be nice if this nonsensical misusage, which obviously is based on
> someone's misunderstanding of the term some years ago (and then spread like
> cancer through the power of the Internet) could be stamped out. Surely "FFL"
> is at least as easy to type as "prime" anyway, and there never was any
> reason other than shortness to replace "fixed focal length" with the
> incorrect term.
>
> N.
>
>
September 29, 2005 4:50:13 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Nostrobino wrote:

> "Siddhartha Jain" <reach.siddhartha@gmail.com> wrote in message
> news:1127924713.491825.16030@g49g2000cwa.googlegroups.com...
>
>>Nostrobino wrote:
>>
>>>Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
>>>"prime."
>>>
>>>A prime lens is the camera lens as distinct from some other lens or
>>>lenticular device (close-up lens, tele converter, etc.) used with it. It
>>>has
>>>meant that since long before zoom lenses became commonplace, and
>>>therefore
>>>no need to use another term to mean "non-zoom."
>>>
>>>"Prime" is properly used in the sense of primary, main, chief or
>>>original--all dictionary definitions for "prime."
>>>
>>>There is NO dictionary definition for "prime" which means fixed focal
>>>length
>>>or single focal length, or fixed or single anything else.
>>>
>>>It would be nice if this nonsensical misusage, which obviously is based
>>>on
>>>someone's misunderstanding of the term some years ago (and then spread
>>>like
>>>cancer through the power of the Internet) could be stamped out. Surely
>>>"FFL"
>>>is at least as easy to type as "prime" anyway, and there never was any
>>>reason other than shortness to replace "fixed focal length" with the
>>>incorrect term.
>>
>>I am aware of the mis-usage of the term *prime* and so guilty of
>>propogating the mis-usage but I feel its time the FFL camp realised
>>that there is no turning back.
>
>
> Well, not necessarily, though of course the more people who misuse the term,
> the harder it will be to correct it.
>
> Most people do not want to use wrong terminology since it makes them look
> ignorant. In the case of "prime" being used to mean FFL, this has only
> spread because readers who have not seen the term before, and then see it
> used by people they assume are knowledgeable, naturally adopt it themselves.
> Thus newbies are caught up in the misusage and (perhaps partly because they
> feel using jargon will make them look knowledgeable too), contribute to the
> spread.
>
> Some will continue to use it anyway, but others will drop it (and some have
> dropped it) when the error is pointed out to them.
>
> N.
>
>

Just because "popular usage" may not appear in a particular dictionary
does not constitute "misuse".

If you speak of a prime lens to photographers, they know what you're
talking about.

Perhaps this should be continued in rec.english.language.anal.purists
September 29, 2005 5:00:14 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

John A. Stovall wrote:

> On 28 Sep 2005 07:33:55 -0700, "Siddhartha Jain"
> <reach.siddhartha@gmail.com> wrote:
>
>
>>Hi,
>>
>>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>>28-75mm) and both with an aperture of f2.8 -
>>- Will the prime be brighter than the zoom because it has fewer lens
>>elements?
>>- Will the prime be sharper wide open than the zoom at 28mm?
>>
>>Ofcourse, a lot will depend on the particular makes and models being
>>compared but is there a rule of thumb?
>
>
> Rule of Thumb: A prime at any focal length and wide open is better
> than a zoom at any focal length wide open.

Except when it's not ... like a really well made fast zoom lens being
compared to a really poorly made slow prime lens.
September 29, 2005 5:01:41 PM

Archived from groups: rec.photo.digital.slr-systems,rec.photo.digital (More info?)

Dr. Joel M. Hoffman wrote:

>>Given two lenses, one a prime (say 28mm) and the other a zoom (say
>>28-75mm) and both with an aperture of f2.8 -
>>- Will the prime be brighter than the zoom because it has fewer lens
>>elements?
>
>
> No. f/2.8 tells you exactly how bright the lens is. (It's almost
> like the old question about a pound of lead and a pound of feathers -
> they do both weigh the same.)
>

However, a pound of gold and a pound of feathers do not.
Anonymous
September 29, 2005 5:15:37 PM

Archived from groups: rec.photo.digital (More info?)

Randall Ainsworth wrote:
> In article <X4adnZDtAfRX5qbeRVn-rQ@comcast.com>, Brion K. Lienhart
> <brionl@lienhart.name> wrote:
>
>> Nope. F:2.8 is solely based on the size of the lens. Obsidian is
>> glass, you can grind it into a lens shape, but if you use it as an
>> element in a lens, you're going to get some reallllllly slow shutter
>> speeds. Of course that's an extreme case, the difference between
>> plain old glass glass, and exotic flouro-silicates is only a few
>> fractions of a percent.
>
> An f/2.8 lens is going to allow a specific amount of light to go
> through regardless of what kind of glass it's made of.

No, you are wrong. A T/2.8 lens will do that, but the amount of light an
f/2.8 lens will let through depends on the transmission of the elements as
well. The difference may only be a few percent.

David
!