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F stops and indoor photography?

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Anonymous
June 9, 2005 3:00:28 PM

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

My wife has owned a Canon A70 for a couple of years. Decent little
camera, but not all I would hope for when taking indoor shots. I
recently purchased a Panasonic FZ5 and the indoor pictures are much
better. I am able to take beautiful shots without flash that would have
been impossible with the A70. I am having a blast with this camera. I
know that some of this can be attributed to the image stabilization.
But, I am trying to understand all the camera characteristics that are
important to taking good indoor photos (flash and non flash).

I've been reading several books on digital photography; some have
mentioned the need for at least an f2.8 capability for low light, on
flash photography. Does this mean all f2.8 capable cameras have
theoretically the same low light ability?

I can find pocket, compact, prosumer, and DSLR cameras that all seem to
have the same capability of taking a pic using a 35mm focal length at
f2.8 (ignoring the use of flash for now). Does this mean that the
amount of light in each camera reaching the sensor is identical?
(Theoretically making them all very similar in their ability to capture
a picture in low light, quality issues aside?).

What function does all that big glass serve on the prosumer and DSLR
cameras? Is it just for reducing aberrations, or is it also serving to
capture more precious photons?

Thank you for the help,

TR
Anonymous
June 9, 2005 4:51:49 PM

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

John,

I believe that is why the DSLRs do so well in low light, being able to
use higher ISO settings, with lower noise than a smaller sensor camera.

But back to my original question- Now assuming all cameras were set to
the same ISO, same focal length, and same, f stop... Is the light
gathering potential of all the same? Or does a bigger lens allow the
camera to gather more light?

Thank you, TR
Anonymous
June 9, 2005 5:21:39 PM

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

On 9 Jun 2005 11:00:28 -0700, "starcolony" <pizza2004man@yahoo.com>
wrote:

>My wife has owned a Canon A70 for a couple of years. Decent little
>camera, but not all I would hope for when taking indoor shots. I
>recently purchased a Panasonic FZ5 and the indoor pictures are much
>better. I am able to take beautiful shots without flash that would have
>been impossible with the A70. I am having a blast with this camera. I
>know that some of this can be attributed to the image stabilization.
>But, I am trying to understand all the camera characteristics that are
>important to taking good indoor photos (flash and non flash).
>
>I've been reading several books on digital photography; some have
>mentioned the need for at least an f2.8 capability for low light, on
>flash photography. Does this mean all f2.8 capable cameras have
>theoretically the same low light ability?

No, there's a little thing called ISO that really affects low light
more than the F stop.

http://www.photoxels.com/tutorial_iso.html


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

"The condition of civil affairs in Texas is anomalous,
singular, and unsatisfactory."

Maj. Gen. Philip H. Sherdan
to
Bvt. Maj. Gen. John A. Rawlins
November 14, 1866
Related resources
Anonymous
June 9, 2005 5:41:25 PM

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

Asaar,

Your explanation makes sense. But, as I look at specific cameras (I'll
choose Panasonic since I am most familiar with this line), the
miniscule FX8, the small FZ5, and the midsize FZ20, all have a
capability of maximum aperture of F2.8 at 35-36mm. But the lens size is
dramatically different between the different models. My guess is the
larger lens allows the aperture to stay large (low f-stop) as the focal
length is increased. For example, the large lens on the FZ20 allows the
camera to utilize the same f2.8 at any focal length, while on the other
two cameras, with smaller lenses, the f stop creeps up as the focal
length is increased.

If I have taken in all this information correctly. The differences
between these camera's ablilities to take low light shots (assuming the
same 36mm focal length and same f2.8), will come down to the amount of
noise created at the various ISO settings?

Thanks, TR
Anonymous
June 9, 2005 5:57:02 PM

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

Let me write this out and see if *I* understand it. I think I'm right,
but if I'm not, I feel certain we'll get a clarification PDQ. The
bigger the hole, the more light comes in, thusly lower f-stop numbers
let in more light. The longer the shutter is open, the longer the
film/sensor is exposed to that light, thusly the smaller fractions of a
second let it in for less time and the larger fractions of a second or
full seconds or even minutes let it in for longer, having more effect
on the film/sensor. The higher the ISO of the film/sensor, the more
effect the light has on the film/sensor at any given amount or time of
exposure. Anyhoo, there's your advantage of DSLR's. They typically
can do better with higher ISO's (bigger sensors). You can usually find
lenses with bigger holes compared to point and shoot or ZLR's. The one
area where they're all similar is that most offer longer exposure times
of 1/60, 1/30, 1/8, etc.. In other words, with a DSLR you can get more
light to a bigger sensor for longer and the higher ISO's will usually
produce less noise because of the larger sensors of the DSLR. Also,
the higher quality glass available for most DSLR's will do a better job
transmitting reality to the image, at least in theory. Once again, in
theory, your ZLR should not be able to produce as clean and well
exposed an image under exact same conditions because the DSLR will have
a lens with a bigger hole putting the available light onto a bigger
sensor. ???
Anonymous
June 9, 2005 8:11:26 PM

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

On 9 Jun 2005 12:51:49 -0700, starcolony wrote:

> But back to my original question- Now assuming all cameras were set to
> the same ISO, same focal length, and same, f stop... Is the light
> gathering potential of all the same? Or does a bigger lens allow the
> camera to gather more light?

When all parameters are the same, the exposures will be the same.
The larger lenses allow larger apertures to be used. So an f/1.4
55mm lens will have its front glass element having a diameter about
twice as large as an f/2.8 55mm lens, and at maximum apertures, will
capture 4 times the amount of light. If you look at the lenses of
cameras that have relatively tiny lenses, don't be surprised if
they're rated at f/5.6 or f/8.0. The really large ones will have
maximum apertures of f/1.4 and f/1.2. I recall a really old, huge
Canon lens for one of their rangefinder cameras that had an aperture
something like f/0.95, and there was an f/1.2 58mm lens for the
Nikon F. Not the sharpest lenses, but really good for taking
pictures in minimal light, as long as you didn't mind lugging around
large hunks of glass.
Anonymous
June 9, 2005 8:11:27 PM

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

On Thu, 09 Jun 2005 16:11:26 -0400, ASAAR <caught@22.com> wrote:

>On 9 Jun 2005 12:51:49 -0700, starcolony wrote:
>
>> But back to my original question- Now assuming all cameras were set to
>> the same ISO, same focal length, and same, f stop... Is the light
>> gathering potential of all the same? Or does a bigger lens allow the
>> camera to gather more light?
>
> When all parameters are the same, the exposures will be the same.
>The larger lenses allow larger apertures to be used. So an f/1.4
>55mm lens will have its front glass element having a diameter about
>twice as large as an f/2.8 55mm lens, and at maximum apertures, will
>capture 4 times the amount of light. If you look at the lenses of
>cameras that have relatively tiny lenses, don't be surprised if
>they're rated at f/5.6 or f/8.0. The really large ones will have
>maximum apertures of f/1.4 and f/1.2. I recall a really old, huge
>Canon lens for one of their rangefinder cameras that had an aperture
>something like f/0.95, and there was an f/1.2 58mm lens for the
>Nikon F. Not the sharpest lenses, but really good for taking
>pictures in minimal light, as long as you didn't mind lugging around
>large hunks of glass.
>

Canon made a lovely F1.0 for the EOS body and I wouldn't mind lugging
that around at all. Then there's the Leica F1.0 Noctilux.

I would never mind lugging around glass like those two lenses.

Here's what one looks like:

http://www.fredmiranda.com/forum/topic2/223012/1

Here's what it will do:

http://www.fredmiranda.com/forum/topic2/223012/2


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

"The condition of civil affairs in Texas is anomalous,
singular, and unsatisfactory."

Maj. Gen. Philip H. Sherdan
to
Bvt. Maj. Gen. John A. Rawlins
November 14, 1866
Anonymous
June 9, 2005 9:13:51 PM

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

Thanks to everyone for the helpful info.

I picked up several books from the library on digital cameras, but non
of them had an explanation that answered my question. They may talk
about aperture and f-stops generically, but not really a comparision as
to the practical low light usefulness of different cameras, lenses,
etc. Especially considering that there are multiple sensor sizes
available, and virtually all lenses need to be converted to comparable
35mm film focal lengths. The Link on ISO provided by John was helpful.
Unfortunately the link at the same site on f-stops was the same
simplified explanation found in most books.

The DSLRs with a quality lens seem to be the ultimate solution, but
quite costly as ASAAR mentions. I'll probably take another look at the
Olympus 8080. The price on these is now under $500. I really like the
look and feel of this camera, but the user interface seemed very
kludgy.

The Panasonic LC1 looks impressive on paper as well. The f2.0 to f2.4
lens with a 2/3" sensor looks like the best spec in a prosumer camera
for low light. I love the retro rangefinder design as well. It is
coming down in price too, but still a little out of my budget for now.

I can start saving up for a nice DSLR and lens and wait for the bugs to
be worked out and the prices to fall. Shouldn't be too many years to
wait.

Cheers, TR
Anonymous
June 9, 2005 9:18:55 PM

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

"starcolony" <pizza2004man@yahoo.com> writes:

> My wife has owned a Canon A70 for a couple of years. Decent little
> camera, but not all I would hope for when taking indoor shots. I
> recently purchased a Panasonic FZ5 and the indoor pictures are much
> better. I am able to take beautiful shots without flash that would have
> been impossible with the A70. I am having a blast with this camera. I
> know that some of this can be attributed to the image stabilization.
> But, I am trying to understand all the camera characteristics that are
> important to taking good indoor photos (flash and non flash).
>
> I've been reading several books on digital photography; some have
> mentioned the need for at least an f2.8 capability for low light, on
> flash photography. Does this mean all f2.8 capable cameras have
> theoretically the same low light ability?

No. (And f2.8 is pretty slow for real available-light photography).

> I can find pocket, compact, prosumer, and DSLR cameras that all seem to
> have the same capability of taking a pic using a 35mm focal length at
> f2.8 (ignoring the use of flash for now). Does this mean that the
> amount of light in each camera reaching the sensor is identical?
> (Theoretically making them all very similar in their ability to capture
> a picture in low light, quality issues aside?).

Yes.

However, the sensor will be more sensitive / less noisy in some
cameras than in others, hence the ability to take useful low-light
photos will be different even though the amount of light reaching the
sensor is the same.

> What function does all that big glass serve on the prosumer and DSLR
> cameras? Is it just for reducing aberrations, or is it also serving to
> capture more precious photons?

Wider zoom range, more light-gathering power, fewer aberrations. Not
all of them in all cases of course :-).
--
David Dyer-Bennet, <mailto:D d-b@dd-b.net>, <http://www.dd-b.net/dd-b/&gt;
RKBA: <http://noguns-nomoney.com/&gt; <http://www.dd-b.net/carry/&gt;
Pics: <http://dd-b.lighthunters.net/&gt; <http://www.dd-b.net/dd-b/SnapshotAlbum/&gt;
Dragaera/Steven Brust: <http://dragaera.info/&gt;
Anonymous
June 9, 2005 9:48:25 PM

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

That link is broke



"John A. Stovall" <johnastovall@earthlink.net> wrote in message
news:3ibha19456ah4ig31ea3244a9dpsulj5n9@4ax.com...
> On Thu, 09 Jun 2005 16:11:26 -0400, ASAAR <caught@22.com> wrote:
>
>>On 9 Jun 2005 12:51:49 -0700, starcolony wrote:
>>
>>> But back to my original question- Now assuming all cameras were set to
>>> the same ISO, same focal length, and same, f stop... Is the light
>>> gathering potential of all the same? Or does a bigger lens allow the
>>> camera to gather more light?
>>
>> When all parameters are the same, the exposures will be the same.
>>The larger lenses allow larger apertures to be used. So an f/1.4
>>55mm lens will have its front glass element having a diameter about
>>twice as large as an f/2.8 55mm lens, and at maximum apertures, will
>>capture 4 times the amount of light. If you look at the lenses of
>>cameras that have relatively tiny lenses, don't be surprised if
>>they're rated at f/5.6 or f/8.0. The really large ones will have
>>maximum apertures of f/1.4 and f/1.2. I recall a really old, huge
>>Canon lens for one of their rangefinder cameras that had an aperture
>>something like f/0.95, and there was an f/1.2 58mm lens for the
>>Nikon F. Not the sharpest lenses, but really good for taking
>>pictures in minimal light, as long as you didn't mind lugging around
>>large hunks of glass.
>>
>
> Canon made a lovely F1.0 for the EOS body and I wouldn't mind lugging
> that around at all. Then there's the Leica F1.0 Noctilux.
>
> I would never mind lugging around glass like those two lenses.
>
> Here's what one looks like:
>
> http://www.fredmiranda.com/forum/topic2/223012/1
>
> Here's what it will do:
>
> http://www.fredmiranda.com/forum/topic2/223012/2
>
>
> ********************************************************
>
> "The condition of civil affairs in Texas is anomalous,
> singular, and unsatisfactory."
>
> Maj. Gen. Philip H. Sherdan
> to
> Bvt. Maj. Gen. John A. Rawlins
> November 14, 1866
Anonymous
June 9, 2005 11:05:57 PM

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

On 9 Jun 2005 13:41:25 -0700, starcolony wrote:

> Your explanation makes sense. But, as I look at specific cameras (I'll
> choose Panasonic since I am most familiar with this line), the
> miniscule FX8, the small FZ5, and the midsize FZ20, all have a
> capability of maximum aperture of F2.8 at 35-36mm. But the lens size is
> dramatically different between the different models. My guess is the
> larger lens allows the aperture to stay large (low f-stop) as the focal
> length is increased. For example, the large lens on the FZ20 allows the
> camera to utilize the same f2.8 at any focal length, while on the other
> two cameras, with smaller lenses, the f stop creeps up as the focal
> length is increased.

I carefully avoided mentioning zoom and fisheye lenses in my
reply. :)  Yes, they complicate matters to some degree, depending
on their design. But that's not the only complication. The
Panasonic FZ20's focal length is NOT f=36mm-432mm, but actually
f=6.0-72mm. The f=36-432mm focal length is provided to indicate
what kind of lens a 35mm camera would have to use in order to take
similar images. This is due to the sensor in the FZ20 being much
smaller than the 24mm x 36mm frame size used in 35mm cameras. So
the sensor size is another complicating factor. But not really in
this case with the Panasonic cameras, as they all use 1/2.5" CCD
sensors.

With a simple zoom lens, where the full light gathering ability is
used at all focal lengths, from wide to tele, the maximum aperture
decreases as the lens is zoomed to the tele end. This is the case
with the FZ5 and FX7, whose max. aperture ranges from, respectively,
F/2.8 to F/3.3, and F/2.8 to F/5.0. The size/diameter of the lens
is pretty much determined by the *tele* end of the zoom, not by the
wide end. So it's not really accurate to describe these as F/2.8
lenses, since the size of the lenses are not determined by the F/2.8
figure, but by the F/3.3 and F/5.0 apertures. These smaller
apertures mean that the lenses can be smaller than the FZ20's lens,
which is a "constant aperture" design, having the full F/2.8
aperture at the tele end of the zoom, which is what forces its lens
to be larger than the other two cameras.


> If I have taken in all this information correctly. The differences
> between these camera's ablilities to take low light shots (assuming the
> same 36mm focal length and same f2.8), will come down to the amount of
> noise created at the various ISO settings?

Yes, (sort of) for the conditions you stated. But the answer
would have been No for focal lengths greater then 36mm, because as I
mentioned above, these cameras don't all have F/2.8 aperture lenses
across the entire zoom range. All other things being equal, when
zoomed towards the tele end, the FZ20's lens is able to gather more
light than the other cameras since its aperture won't decrease below
F/2.8.

The reason I said "(sort of)" is because depending on the type of
picture you're trying to take, noise (or grain, for film cameras) is
just a side effect of insufficient light. For my way of looking at
it, the ability to take low light pictures is determined not only by
the highest available ISO setting, but also by the lens's maximum
aperture (ignoring shutter speed). Having insufficient light, so
that the pictures are very dark with almost zero detail, is far
worse, to me anyway, than pictures taken using the same noisy
maximum ISO setting, where there's much more available light. The
objects in the pictures could then actually be seen and recognized,
even if they are marred by noise or grain. So what determines a
camera's low light capability depends on more than just the noise it
generates, but the photographer's preferences as well.

To put this in more concrete terms, take two similar cameras, A
and B. There are no differences between them up to ISO 200. But at
ISO 400, camera A has a very slight amount of noticeable noise that
you find acceptable. Camera B has a bit more noise at ISO 400.
Enough to cause you to reject it as being too noisy. So *you* would
say that camera A is a "better" low light camera than camera B. But
unlike camera A, camera B could also be set to ISO 800, which would
(naturally) produce even more noise in its images. As I want to use
the camera to take candid pictures in dark, smoky bars (without
using flash), I'd say that for my purposes, camera B is better in
low light situations, because the additional noise isn't that big a
factor for me, if it allows me to get the shots I'm looking for.

Of course for those people that want little to zero noise in *all*
of their pictures, they wouldn't be using their camera's highest ISO
setting anyway, and what they call "low light" may be much brighter
than what my definition would be. They wouldn't be wrong either,
it's just that their expectations are different.
Anonymous
June 9, 2005 11:22:53 PM

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

On 9 Jun 2005 13:57:02 -0700, Kitt wrote:

> Let me write this out and see if *I* understand it. I think I'm right,
> but if I'm not, I feel certain we'll get a clarification PDQ.
> . . .
> Once again, in
> theory, your ZLR should not be able to produce as clean and well
> exposed an image under exact same conditions because the DSLR will have
> a lens with a bigger hole putting the available light onto a bigger
> sensor. ???

That's pretty much the way I see it. There may be a few special
cases that "prove" the rule, such as the Olympus 8080 which not only
has a fairly large aperture lens, but its quality is probably better
than a number of the kit lenses supplied with some DSLRs. Put a
really good lens on the DSLR and you'll get better, cleaner images
though. But at such a high price that many amateur photographers
would be discouraged from going that route.
Anonymous
June 9, 2005 11:24:40 PM

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

On Thu, 09 Jun 2005 16:09:47 -0500, John A. Stovall wrote:

> From: John A. Stovall <johnastovall@earthlink.net>
> Newsgroups: rec.photo.digital
> Subject: Re: F stops and indoor photography?
> Date: Thu, 09 Jun 2005 16:09:47 -0500
> Organization: Texas A&M University, College Station, Texas
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> X-Newsreader: Forte Agent 1.9/32.560
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>
> On Thu, 09 Jun 2005 16:11:26 -0400, ASAAR <caught@22.com> wrote:
>
> >On 9 Jun 2005 12:51:49 -0700, starcolony wrote:
> >
> >> But back to my original question- Now assuming all cameras were set to
> >> the same ISO, same focal length, and same, f stop... Is the light
> >> gathering potential of all the same? Or does a bigger lens allow the
> >> camera to gather more light?
> >
> > When all parameters are the same, the exposures will be the same.
> >The larger lenses allow larger apertures to be used. So an f/1.4
> >55mm lens will have its front glass element having a diameter about
> >twice as large as an f/2.8 55mm lens, and at maximum apertures, will
> >capture 4 times the amount of light. If you look at the lenses of
> >cameras that have relatively tiny lenses, don't be surprised if
> >they're rated at f/5.6 or f/8.0. The really large ones will have
> >maximum apertures of f/1.4 and f/1.2. I recall a really old, huge
> >Canon lens for one of their rangefinder cameras that had an aperture
> >something like f/0.95, and there was an f/1.2 58mm lens for the
> >Nikon F. Not the sharpest lenses, but really good for taking
> >pictures in minimal light, as long as you didn't mind lugging around
> >large hunks of glass.
> >
>
> Canon made a lovely F1.0 for the EOS body and I wouldn't mind lugging
> that around at all. Then there's the Leica F1.0 Noctilux.
>
> I would never mind lugging around glass like those two lenses.
>
> Here's what one looks like:
>
> http://www.fredmiranda.com/forum/topic2/223012/1
>
> Here's what it will do:
>
> http://www.fredmiranda.com/forum/topic2/223012/2
>
Anonymous
June 10, 2005 12:23:32 AM

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

I almost bought an 8080 but went with the D70 instead, as I have a lot of
Nikon Lenses from my 35mm camera that fit the D70.

I think the biggest problem in your puzzle is the different sizes of image
sensors. The larger sensors on DSLR's, and the area that has to be covered
on a 35mm camera, require large hunks of glass to get a lot of light to the
sensor. Many photogs like to work with a low ISO or slower film speeds to
keep the noise and grain down. Hence, you either have to use a slow shutter
speed (read: tripod) or a larger aperture so you can hand-hold the shot.

When the size of your image sensor is about the size of your thumbnail, the
lens can be pretty small and still deliver plenty of light to the sensor.
Some of the better point and shoot cameras are capable of producing amazing
images, but don't have the versatility of a DSLR. The ability to swap
lenses and the technology that is now going into DSLR sensors is what gives
them an advantage.


"starcolony" <pizza2004man@yahoo.com> wrote in message
news:1118362431.278428.3630@g49g2000cwa.googlegroups.com...
> Thanks to everyone for the helpful info.
>
> I picked up several books from the library on digital cameras, but non
> of them had an explanation that answered my question. They may talk
> about aperture and f-stops generically, but not really a comparision as
> to the practical low light usefulness of different cameras, lenses,
> etc. Especially considering that there are multiple sensor sizes
> available, and virtually all lenses need to be converted to comparable
> 35mm film focal lengths. The Link on ISO provided by John was helpful.
> Unfortunately the link at the same site on f-stops was the same
> simplified explanation found in most books.
>
> The DSLRs with a quality lens seem to be the ultimate solution, but
> quite costly as ASAAR mentions. I'll probably take another look at the
> Olympus 8080. The price on these is now under $500. I really like the
> look and feel of this camera, but the user interface seemed very
> kludgy.
>
> The Panasonic LC1 looks impressive on paper as well. The f2.0 to f2.4
> lens with a 2/3" sensor looks like the best spec in a prosumer camera
> for low light. I love the retro rangefinder design as well. It is
> coming down in price too, but still a little out of my budget for now.
>
> I can start saving up for a nice DSLR and lens and wait for the bugs to
> be worked out and the prices to fall. Shouldn't be too many years to
> wait.
>
> Cheers, TR
>
June 10, 2005 12:28:26 AM

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

"starcolony" <pizza2004man@yahoo.com> wrote in message
news:1118346709.758594.120680@g43g2000cwa.googlegroups.com...
> John,
>
> I believe that is why the DSLRs do so well in low light, being able to
> use higher ISO settings, with lower noise than a smaller sensor camera.
>
> But back to my original question- Now assuming all cameras were set to
> the same ISO, same focal length, and same, f stop... Is the light
> gathering potential of all the same? Or does a bigger lens allow the
> camera to gather more light?
Yes.
Jim
Anonymous
June 10, 2005 12:58:43 AM

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

Keep in mind that, with these particular cameras, the focal length indicated
is not the actual focal length of the lenses, but rather the effective
equivalents when compared to a 35mm format camera. These particular cameras
you mention all have chips much smaller than 24x36mm, and the actual lens
focal lengths are going to be much shorter than the indicated 35mm
equivalents. Do they all have the same size chip? If not, then the actual
focal lengths will vary from camera to camera, and since the aperture
opening diameter is defined as f/stop (focal length divided by stop
number), for the apertures to remain the same the lens diameters will have
to vary.


"starcolony" <pizza2004man@yahoo.com> wrote in message
news:1118349685.072305.240410@g14g2000cwa.googlegroups.com...
> Asaar,
>
> Your explanation makes sense. But, as I look at specific cameras (I'll
> choose Panasonic since I am most familiar with this line), the
> miniscule FX8, the small FZ5, and the midsize FZ20, all have a
> capability of maximum aperture of F2.8 at 35-36mm. But the lens size is
> dramatically different between the different models. My guess is the
> larger lens allows the aperture to stay large (low f-stop) as the focal
> length is increased. For example, the large lens on the FZ20 allows the
> camera to utilize the same f2.8 at any focal length, while on the other
> two cameras, with smaller lenses, the f stop creeps up as the focal
> length is increased.
>
> If I have taken in all this information correctly. The differences
> between these camera's ablilities to take low light shots (assuming the
> same 36mm focal length and same f2.8), will come down to the amount of
> noise created at the various ISO settings?
>
> Thanks, TR
>
Anonymous
June 10, 2005 12:58:44 AM

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

On Thu, 09 Jun 2005 20:58:43 GMT, Ken Burns wrote:

> Do they all have the same size chip? If not, then the actual
> focal lengths will vary from camera to camera, and since the aperture
> opening diameter is defined as f/stop (focal length divided by stop
> number), for the apertures to remain the same the lens diameters will have
> to vary.

That's the same thing I thought of, but it turns out that they all
use 1/2.5" sensors, at least the ones I looked up do. Here's some
of what I collected, mostly from StevesDigitals.com (if I recall the
URL correctly).

Panasonic FZ5:
Lens: f=6.0-72mm. 36 - 432mm (equiv.) F2.8-3.3
Lens: Wide: F2.8 - F8; Tele: F3.3 - F8
Sensor • 1/2.5" CCD, 5.36 million total pixels

Panasonic DMC-FX5:
Lens: f=5.8-17.4mm (35mm equiv: 35-105mm) F2.8 - 4.9
Sensor: 1/2.5" CCD

Panasonic DMC-FX7:
Lens: f = 5.8 - 17.4 mm (35mm Equiv.:35-105mm); F2.8 - 5.0
Lens: Wide: F2.8/F5.6, Tele: F5.0/F10
Sensor: 1/2.5" CCD

Panasonic Lumix DMC-FZ20:
Lens: f=6.0-72mm (35mm equivalent: 36-432mm)
Lens: Constant F2.8 max. aperture (Wide-Tele)
Sensor: 1/2.5" CCD
Anonymous
June 10, 2005 1:35:41 AM

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

"starcolony" <pizza2004man@yahoo.com> wrote in message
news:1118346709.758594.120680@g43g2000cwa.googlegroups.com...
> John,
>
> I believe that is why the DSLRs do so well in low light, being able to
> use higher ISO settings, with lower noise than a smaller sensor camera.
>
> But back to my original question- Now assuming all cameras were set to
> the same ISO, same focal length, and same, f stop... Is the light
> gathering potential of all the same?

ISO has nothing to do with a lens's light-gathering capabilities, that just
defines the multiplication of the sensors' outputs. The proper notation is
"f/stop" which means: focal length (f) divided by aperture number (stop),
and that defines the effective diameter of the aperture diaphragm opening.
Therefore, it doesn't really matter if the focal length varies since the
f/stop already takes that into account on a constant aperture lens. If the
f/stop setting is the same on different lenses, or on a zoom lens at
different focal lengths, the light passage will be the same.

>Or does a bigger lens allow the
> camera to gather more light?

A larger f/stop (focal length divided by aperture number) allows more light
to pass through. The diameter of a lens's front element isn't necessarily a
good indicator of the amount of light allowed through the lens since
different optical configurations require different diameter elements. For
example, my Sigma 28mm f/1.8 has a larger front element diameter than does
my Nikkor 50mm f/1.8 because are of vastly different optical configurations.
Anonymous
June 10, 2005 2:18:38 AM

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

Ken Burns wrote:

> "starcolony" <pizza2004man@yahoo.com> wrote in message
> news:1118346709.758594.120680@g43g2000cwa.googlegroups.com...
>
>>John,
>>
>>I believe that is why the DSLRs do so well in low light, being able to
>>use higher ISO settings, with lower noise than a smaller sensor camera.
>>
>>But back to my original question- Now assuming all cameras were set to
>>the same ISO, same focal length, and same, f stop... Is the light
>>gathering potential of all the same?
>
>
> ISO has nothing to do with a lens's light-gathering capabilities, that just
> defines the multiplication of the sensors' outputs. The proper notation is
> "f/stop" which means: focal length (f) divided by aperture number (stop),
> and that defines the effective diameter of the aperture diaphragm opening.
> Therefore, it doesn't really matter if the focal length varies since the
> f/stop already takes that into account on a constant aperture lens. If the
> f/stop setting is the same on different lenses, or on a zoom lens at
> different focal lengths, the light passage will be the same.
>
>
>>Or does a bigger lens allow the
>>camera to gather more light?
>
>
> A larger f/stop (focal length divided by aperture number) allows more light
> to pass through. The diameter of a lens's front element isn't necessarily a
> good indicator of the amount of light allowed through the lens since
> different optical configurations require different diameter elements. For
> example, my Sigma 28mm f/1.8 has a larger front element diameter than does
> my Nikkor 50mm f/1.8 because are of vastly different optical configurations.
>
>
Hi,
I think this fellow has lot of reading to do or needs to enroll on a
course at local college or something, Sigh! Asking is not a crime,
pretending is. Good for him.
Tony
Anonymous
June 10, 2005 2:34:35 AM

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

David Dyer-Bennet wrote:
> "starcolony" <pizza2004man@yahoo.com> writes:
>
>
>>My wife has owned a Canon A70 for a couple of years. Decent little
>>camera, but not all I would hope for when taking indoor shots. I
>>recently purchased a Panasonic FZ5 and the indoor pictures are much
>>better. I am able to take beautiful shots without flash that would have
>>been impossible with the A70. I am having a blast with this camera. I
>>know that some of this can be attributed to the image stabilization.
>>But, I am trying to understand all the camera characteristics that are
>>important to taking good indoor photos (flash and non flash).
>>
>>I've been reading several books on digital photography; some have
>>mentioned the need for at least an f2.8 capability for low light, on
>>flash photography. Does this mean all f2.8 capable cameras have
>>theoretically the same low light ability?
>
>
> No. (And f2.8 is pretty slow for real available-light photography).
>
>
>>I can find pocket, compact, prosumer, and DSLR cameras that all seem to
>>have the same capability of taking a pic using a 35mm focal length at
>>f2.8 (ignoring the use of flash for now). Does this mean that the
>>amount of light in each camera reaching the sensor is identical?
>>(Theoretically making them all very similar in their ability to capture
>>a picture in low light, quality issues aside?).
>
>
> Yes.
>
> However, the sensor will be more sensitive / less noisy in some
> cameras than in others, hence the ability to take useful low-light
> photos will be different even though the amount of light reaching the
> sensor is the same.
>
>
>>What function does all that big glass serve on the prosumer and DSLR
>>cameras? Is it just for reducing aberrations, or is it also serving to
>>capture more precious photons?
>
>
> Wider zoom range, more light-gathering power, fewer aberrations. Not
> all of them in all cases of course :-).
Hi,
Big difference in digital cameras is they're not only a hardware device.
It's got firmware which plays very important roll. Not like old film
cameras. Well written firmware is a BIG plus for any camera.
Tony
Anonymous
June 10, 2005 6:17:44 AM

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

> Hi,
> I think this fellow has lot of reading to do or needs to enroll on a
> course at local college or something, Sigh! Asking is not a crime,
> pretending is. Good for him.
> Tony

Nothing I have said is incorrect. If you disagree with me, then you are the
one who needs to enroll at a local college.
Anonymous
June 10, 2005 12:19:37 PM

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

On Thu, 09 Jun 2005 19:24:40 -0400, ASAAR <caught@22.com> wrote:

Your point?
********************************************************

"The condition of civil affairs in Texas is anomalous,
singular, and unsatisfactory."

Maj. Gen. Philip H. Sherdan
to
Bvt. Maj. Gen. John A. Rawlins
November 14, 1866
Anonymous
June 10, 2005 1:58:31 PM

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

Ken Burns <kenburns@twave.net> wrote:

: "starcolony" <pizza2004man@yahoo.com> wrote in message

: >Or does a bigger lens allow the
: > camera to gather more light?

: A larger f/stop (focal length divided by aperture number) allows more
: light to pass through. The diameter of a lens's front element isn't
: necessarily a good indicator of the amount of light allowed through the
: lens since different optical configurations require different diameter
: elements. For example, my Sigma 28mm f/1.8 has a larger front element
: diameter than does my Nikkor 50mm f/1.8 because are of vastly different
: optical configurations.

True. But if both lenses are the same focal length and roughly the same
internal makeup, a larger diameter front element MAY indicate a slightly
higher light gathering ability. Of course this would be numerically
indicated in the lowest aperture number on this lens. At least this seems
to be true. Take a telescope (a camera lens with or without a camera). A
telescope that is 3" in diameter will gather less light and thus be able
to resolve only brighter objects than one 3' in diameter. Thus a camera
lens with a front element 3' in diameter (like such a thing is likely)
would be able to gather more photons and thus resolve an image of a faint
object much better than one of the same focal length with a 3" front
element. But as was just pointed out, different lenses have different
internal configurations that can strongly influence the light gathering
(and concentrating) ability. And even with the relatively small range of
front element diameter, combined with differences in internal makeup, and
differences in physical dimensions of the aperture opening will make that
one measurement (front element diameter) alone much less indicative of
"brightness". So to make it more easy to compare different lenses we
normally use the f/stop numbers to indicate how a specific quantity of
light will be presented to the image capture medium.

Now changing the focal length of the lens will change how much light will
make it to the image sensor (or film). So many very long lenses will have
a large front element to counteract the losses. But an extreme wide angle
lens will also require a wide lens to keep the edges of the lens itself
from encroaching on the image. So you may have a wide angle lens and a
tele lens with the same f/stop and the same front element size, but the
dimension is wide for different reasons. And this is all assuming the
image sensor it the same size. A smaller sensor may require a smaller lens
diameter to achieve the same result. :)  Variables all over the place. :) 

At least this is how I think of it.

Randy

==========
Randy Berbaum
Champaign, IL
Anonymous
June 10, 2005 4:08:55 PM

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

"Randy Berbaum" <rberbaum@bluestem.prairienet.org> wrote in message
news:D 8bo87$n0g$1@wildfire.prairienet.org...
> Ken Burns <kenburns@twave.net> wrote:
>
> : "starcolony" <pizza2004man@yahoo.com> wrote in message
>
> : >Or does a bigger lens allow the
> : > camera to gather more light?
>
> : A larger f/stop (focal length divided by aperture number) allows more
> : light to pass through. The diameter of a lens's front element isn't
> : necessarily a good indicator of the amount of light allowed through the
> : lens since different optical configurations require different diameter
> : elements. For example, my Sigma 28mm f/1.8 has a larger front element
> : diameter than does my Nikkor 50mm f/1.8 because are of vastly different
> : optical configurations.
>
> True. But if both lenses are the same focal length and roughly the same
> internal makeup, a larger diameter front element MAY indicate a slightly
> higher light gathering ability.

That is very true, but its very important to realize the effect of the
optical configuration, or as you stated, the internal makeup. Another
example of optical configuration effecting the overall diameter would be two
other lenses I own. I have an old Schneider 90mm f/6.3 Angulon and a newer
Scheider 90mm f/8 Super Angulon. The f/6.3 lens is smaller in diameter than
the f/8, yet its maximum aperture is larger while the focal lengths are
equal. The Angulon is based on the old Goerz WA Dagor design while the
Super Angulon evolved from the Zeiss Biogon concept. However, the Angulon
has a much narrower angle of coverage than the Super Angulon.

Good examples in the real world of the relationships between focal lengths,
diameters, and optical configurations would be any of the large format lens
systems by Schneider, Rodenstock, Nikon, Fuji, etc. Take for example the
Schneider APO-Symmar system. These lenses cover a range of focal lengths at
a constant maximum aperture throughout the range, except for those lenses at
the longest focal lengths, which for practical reasons (probably mostly
economic!) have smaller max apertures. Each lens is of the same basic
optical design, so the constant aperture is acheived by increasing diameters
proportionately as the focal lengths increase. However, if we look at the
Super Angulon series of lenses, we can find lenses of equal (or near equal)
focal lengths to the APO-Symmar lenses that have smaller maximum apertures
while having a much larger diameter front element. A good comparison here
would be the 210 APO-Symmar and the 210 Super Angulon. The APO-Symmar is
very compact when compared to the Super Angulon. They are based on totally
different optical configurations.
Anonymous
June 10, 2005 6:50:04 PM

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

On Fri, 10 Jun 2005 08:19:37 -0500, John A. Stovall wrote:

> Your point?

Didn't get a chance to make one. I intended to reply after a
short delay, probably to check something else out, and must have
accidentally clicked the [SEND] button which is adjacent to the
[SAVE] button. That's the only way you'll ever see excessive,
irrelevant quotes in my replies. :) 
Anonymous
June 11, 2005 12:50:23 AM

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

Ken Burns wrote:
>
> > Hi,
> > I think this fellow has lot of reading to do or needs to enroll on a
> > course at local college or something, Sigh! Asking is not a crime,
> > pretending is. Good for him.
> > Tony
>
> Nothing I have said is incorrect. If you disagree with me, then you are the
> one who needs to enroll at a local college.

Tony was referring to the OP, not you.

Colin
Anonymous
June 11, 2005 12:50:24 AM

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

"Colin D" <ColinD@killspam.127.0.0.1> wrote in message
news:42A9544F.196BDF33@killspam.127.0.0.1...
>
>
> Ken Burns wrote:
>>
>> > Hi,
>> > I think this fellow has lot of reading to do or needs to enroll on a
>> > course at local college or something, Sigh! Asking is not a crime,
>> > pretending is. Good for him.
>> > Tony
>>
>> Nothing I have said is incorrect. If you disagree with me, then you are
>> the
>> one who needs to enroll at a local college.
>
> Tony was referring to the OP, not you.
>
> Colin

Sorry about that. I retract the statement.

KB
!