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Definition of DSLR

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Anonymous
May 15, 2005 8:30:21 PM

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

A single lens reflex used to be considered
a camera with a viewfinder that imaged through
the lens. But nearly all digital cameras do this,
albeit using an electronic screen for the image.
So would the term, DSLR now have to include
a viewfinder that allows the eye to see the
lens image directly? Does it also mean
the camera must have removable lenses?
-Rich

More about : definition dslr

Anonymous
May 15, 2005 8:50:30 PM

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

RichA wrote:

> A single lens reflex used to be considered
> a camera with a viewfinder that imaged through
> the lens. But nearly all digital cameras do this,
> albeit using an electronic screen for the image.
> So would the term, DSLR now have to include
> a viewfinder that allows the eye to see the
> lens image directly? Does it also mean
> the camera must have removable lenses?

This was all debated, unsatisfactorilly to some, during the forming of
this ng and the .zlr ng.

Please let sleeping dogs lie.

Cheers,
Alan


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Anonymous
May 15, 2005 9:50:59 PM

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

"Alan Browne" <alan.browne@freelunchVideotron.ca> wrote in message
news:D 68cmg$sbp$2@inews.gazeta.pl...
> RichA wrote:
>
> > A single lens reflex used to be considered
> > a camera with a viewfinder that imaged through
> > the lens. But nearly all digital cameras do this,
> > albeit using an electronic screen for the image.
> > So would the term, DSLR now have to include
> > a viewfinder that allows the eye to see the
> > lens image directly? Does it also mean
> > the camera must have removable lenses?
>
> This was all debated, unsatisfactorilly to some, during the forming of
> this ng and the .zlr ng.
>

What does zlr mean, anyway?

Greg
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May 16, 2005 2:23:58 AM

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

RichA <none@none.com> wrote in news:06cf81l4i3s7939irb10kjkdufejb3f2mh@
4ax.com:

> A single lens reflex used to be considered
> a camera with a viewfinder that imaged through
> the lens. But nearly all digital cameras do this,
> albeit using an electronic screen for the image.
> So would the term, DSLR now have to include
> a viewfinder that allows the eye to see the
> lens image directly? Does it also mean
> the camera must have removable lenses?
> -Rich

To be similar to over 99% of SLR camera it would need to have
interchangeable lenses. A camera that is technically a D-SLR, but with a
fixed lens has little relevance to this group, since it is an oddball and
different in important ways to all other cameras discussed here.

The only D-SLRs I know of that don't have interchangeable lenses are the
Olympus E-10 and the Olympus E-20. But the newer of the 2 was released 3.5
years ago and Olympus have not continued that line, they have instead
released interchangeable lens D-SLRs.



--
Mark Heyes (New Zealand)
See my pics at www.gigatech.co.nz (last updated 3-May-05)
"There are 10 types of people, those that
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Anonymous
May 16, 2005 3:18:25 AM

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

"RichA" <none@none.com> wrote in message
news:06cf81l4i3s7939irb10kjkdufejb3f2mh@4ax.com...
>A single lens reflex used to be considered
> a camera with a viewfinder that imaged through
> the lens. But nearly all digital cameras do this,
> albeit using an electronic screen for the image.
> So would the term, DSLR now have to include
> a viewfinder that allows the eye to see the
> lens image directly? Does it also mean
> the camera must have removable lenses?
> -Rich

The key word is "reflex", implying the use of a mirror. Only what are
considered SLRs (or the now-discontinued ZLRs from Olympus) use mirrors to
provide the TTL viewfinder image.

Martin
May 16, 2005 5:01:59 AM

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

If the EVF is improved to the point where it is actually usable, and
lens/sensor aberrations are automatically corrected by software, and the
lens has a reasonable zoom range, will the comparitively ancient
interchangeable SLR form factor (dating back to the 1930s: 3/4 of a century)
survive?
Anonymous
May 16, 2005 6:47:30 AM

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

In article <d68cmg$sbp$2@inews.gazeta.pl>, Alan Browne
<alan.browne@freelunchVideotron.ca> wrote:

> Please let sleeping dogs lie.
>
> Cheers,
> Alan

Sleeping dogs don't hardly talk... How come you think they lie?
Anonymous
May 16, 2005 6:47:31 AM

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

Steve Cutchen wrote:
> In article <d68cmg$sbp$2@inews.gazeta.pl>, Alan Browne
> <alan.browne@freelunchVideotron.ca> wrote:
>
>> Please let sleeping dogs lie.
>>
>> Cheers,
>> Alan
>
> Sleeping dogs don't hardly talk... How come you think they lie?

They're always telling you they are chasing a rabbit, and you can see
it ain't so.
Anonymous
May 16, 2005 10:34:24 AM

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

G.T. wrote:
[]
> What does zlr mean, anyway?

Zoom Lens Reflex - often used to describe the higher-end point-and-shoot
cameras which resemble SLRs in shape and handling but do not have a full
interchangeable lens capability. The reflex is electronic rather than by
mirrors.

David
Anonymous
May 16, 2005 2:44:35 PM

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

G.T. wrote:

> What does zlr mean, anyway?

It's a term coined by one of the vendors (Pentax IIRC) to describe the
more advanced all-in-one camera. Typical examples include the Minolta
A1/A2, Sony 727,828 and many others. Usualy characteristics: full set
of photographic controls (ISO, S, A, exp comp, etc. etc.), a very good
to excellent quality zoom lens covering a focal length of about 28mm to
200mm (in 35mm equivalent) and a 35mm type flash shoe. Some have a
reflex mirror, some have two monitors (back and viewfinder). Usually
have fairly small sensors.

The main non-SLR characteristic is the absence of interchangeable
lenses. This was one reason why this NG ended up being called
..slr-systems instead of .slr

In the end this group (which was the sole original proposal) is
successful.

Of the "tack onto the proposal" groups (zlr, point+shoot and
rangefinder), only zlr has managed to be very modestly successful. P+S
is a few posts a day, rangefinder is a few posts per month.

Cheers,
Alan


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Anonymous
May 16, 2005 2:44:36 PM

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

"Alan Browne" <alan.browne@freelunchVideotron.ca> wrote in message
news:D 6abk9$k8n$1@inews.gazeta.pl...
> G.T. wrote:
>
> > What does zlr mean, anyway?
>
> It's a term coined by one of the vendors (Pentax IIRC) to describe the
> more advanced all-in-one camera. Typical examples include the Minolta
> A1/A2, Sony 727,828 and many others. Usualy characteristics: full set
> of photographic controls (ISO, S, A, exp comp, etc. etc.), a very good
> to excellent quality zoom lens covering a focal length of about 28mm to
> 200mm (in 35mm equivalent) and a 35mm type flash shoe. Some have a
> reflex mirror, some have two monitors (back and viewfinder). Usually
> have fairly small sensors.
>
> The main non-SLR characteristic is the absence of interchangeable
> lenses. This was one reason why this NG ended up being called
> .slr-systems instead of .slr
>
> In the end this group (which was the sole original proposal) is
> successful.
>
> Of the "tack onto the proposal" groups (zlr, point+shoot and
> rangefinder), only zlr has managed to be very modestly successful. P+S
> is a few posts a day, rangefinder is a few posts per month.
>

Thanks Alan. BTW, how many digital rangefinders are available?

Greg
Anonymous
May 16, 2005 4:33:18 PM

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

G.T. wrote:

> Thanks Alan. BTW, how many digital rangefinders are available?

I really don't follow it. There is a very nice Leica M-mount Epson
which I believe uses the same sensor as the 7D, D100/D70, *istD.

http://www.dpreview.com/reviews/specs/Epson/epson_rd1.a...
(No review, just the facts, I've never heard of anyone owning one).

I don't know of any others.

Cheers,
Alan

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May 17, 2005 12:15:26 AM

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

birdman wrote:
> If the EVF is improved to the point where it is actually usable, and
> lens/sensor aberrations are automatically corrected by software, and the
> lens has a reasonable zoom range, will the comparitively ancient
> interchangeable SLR form factor (dating back to the 1930s: 3/4 of a century)
> survive?
>
>
No it won't.
When the EVF provides great resolution with high refresh rates and no
lag, then the mirror can go. Interchangeable lens bodies will stay.
The SLR form factor isn't decided by limitations imposed by reflex
mirrors/prism. It would be easy to make a impractically small DSLR
loaded with features. If you want instant access to functions, then you
need lots of buttons and dials. These need to be in a place where your
fingers can get at them easily. That's why many zlrs use an slr like
design, even if many are to small for my fingers. It's also why pro
cameras are usually quite big.
Anonymous
May 17, 2005 3:15:35 AM

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

On Mon, 16 May 2005 12:33:18 -0400, Alan Browne
<alan.browne@freelunchVideotron.ca> wrote:

>G.T. wrote:
>
>> Thanks Alan. BTW, how many digital rangefinders are available?
>
>I really don't follow it. There is a very nice Leica M-mount Epson
>which I believe uses the same sensor as the 7D, D100/D70, *istD.
>
>http://www.dpreview.com/reviews/specs/Epson/epson_rd1.a...
>(No review, just the facts, I've never heard of anyone owning one).

It's on my possible's list but the problem I see is the rangerfinder
base is short. I would have hope they would have used the long base
found in the M body Leicas.


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

"Man came silently into the world."

Pierre Teilhard de Chardin
_The Phenomenon Of Man_
Anonymous
May 17, 2005 3:15:36 AM

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

John A. Stovall wrote:

> It's on my possible's list but the problem I see is the rangerfinder
> base is short. I would have hope they would have used the long base
> found in the M body Leicas.

What do you mean by "long base"?

I assume you mean some leverage or magnification effect in the
viewfinder optics? (I seem to recall that Leica M6's have different
magnification in the VF).

If that is the case, then it would be odd that the Epson doesn't offer
similar options, esp. considering the price.

Cheers,
Alan.

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Anonymous
May 17, 2005 5:48:48 AM

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

In article <d6bj4k$rb6$1@inews.gazeta.pl>,
Alan Browne <alan.browne@freelunchVideotron.ca> wrote:
>John A. Stovall wrote:
>
>> It's on my possible's list but the problem I see is the rangerfinder
>> base is short. I would have hope they would have used the long base
>> found in the M body Leicas.
>
>What do you mean by "long base"?
>
>I assume you mean some leverage or magnification effect in the
>viewfinder optics? (I seem to recall that Leica M6's have different
>magnification in the VF).

The "long base" is short for "long baseline" -- that is the
separation between the two forward-looking optics of the rangefinder.
The greater that baseline, the more sensitive the rangefinder mechanism
is, and thus the easier to use.

Most binoculars increase your baseline, so you get better depth
perception. Note that the Objective lenses are more widely spaced than
the eyepieces, which are (of course) constrained by the spacing of your
eyes.

Even if you simply set up a pair of simple periscopes, rigidly
mounted to a common frame, so the points from which you are looking are
more widely separated, you will find your ability to judge distance
improved.

>If that is the case, then it would be odd that the Epson doesn't offer
>similar options, esp. considering the price.


The mechanics of a long baseline require a bit more work in the
design of the camera body. Magnification is easy to add, separating the
objective ends of the rangefinder in an existing body design may be more
difficult -- depending on what else is in the way. (In film cameras,
things like the rewind knob and spindle, and a top-mounted film advance
lever may contribute to the list of obstructions.

Enjoy,
DoN.

--
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Anonymous
May 17, 2005 1:01:43 PM

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

DoN. Nichols wrote:

> In article <d6bj4k$rb6$1@inews.gazeta.pl>,
> Alan Browne <alan.browne@freelunchVideotron.ca> wrote:
>
>>John A. Stovall wrote:
>>
>>
>>>It's on my possible's list but the problem I see is the rangerfinder
>>>base is short. I would have hope they would have used the long base
>>>found in the M body Leicas.
>>
>>What do you mean by "long base"?
>>
>>I assume you mean some leverage or magnification effect in the
>>viewfinder optics? (I seem to recall that Leica M6's have different
>>magnification in the VF).
>
>
> The "long base" is short for "long baseline" -- that is the
> separation between the two forward-looking optics of the rangefinder.
> The greater that baseline, the more sensitive the rangefinder mechanism
> is, and thus the easier to use.

Ah, makes sense.

Cheers,
Alan


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Anonymous
May 17, 2005 7:18:35 PM

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

On Tue, 17 May 2005 09:01:43 -0400, Alan Browne
<alan.browne@freelunchVideotron.ca> wrote:

>DoN. Nichols wrote:
>
>> In article <d6bj4k$rb6$1@inews.gazeta.pl>,
>> Alan Browne <alan.browne@freelunchVideotron.ca> wrote:
>>
>>>John A. Stovall wrote:
>>>
>>>
>>>>It's on my possible's list but the problem I see is the rangerfinder
>>>>base is short. I would have hope they would have used the long base
>>>>found in the M body Leicas.
>>>
>>>What do you mean by "long base"?
>>>
>>>I assume you mean some leverage or magnification effect in the
>>>viewfinder optics? (I seem to recall that Leica M6's have different
>>>magnification in the VF).
>>
>>
>> The "long base" is short for "long baseline" -- that is the
>> separation between the two forward-looking optics of the rangefinder.
>> The greater that baseline, the more sensitive the rangefinder mechanism
>> is, and thus the easier to use.
>
>Ah, makes sense.
>
>Cheers,
>Alan

There has to be a point at which increasing the baseline no longer
benefits the ability to focus, given average human eyesight.
But I remember military binoculars that could have their objective
lenses separated by up to 2 feet.
-Rich
Anonymous
May 17, 2005 8:35:13 PM

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

RichA wrote:

> There has to be a point at which increasing the baseline no longer
> benefits the ability to focus, given average human eyesight.
> But I remember military binoculars that could have their objective
> lenses separated by up to 2 feet.

Range finders for artillery had to be accurate well beyond the
hyperfocal of the lens to determine distance accurately (at least that's
what I assume you're referring to). So a stereo rangefinding solution
with a wide baseline is desirable.

For a rangefinder camera, if my assumptions are correct, it would only
need rangefinding accuracy up to a little beyond the hyperfocal distance
for the largest aperture of the longest lens in the collection for the
camera. The longest lens I can find for Leica M is 180mm f/2.8 so that
comes to a little over 460 meters (for 0.025 CoC).

It may all 'wash' out in the design of the focus coupling to the lens, I
really have no idea.

Cheers,
Alan.


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Anonymous
May 18, 2005 6:07:20 AM

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

On Tue, 17 May 2005 16:35:13 -0400, Alan Browne
<alan.browne@freelunchVideotron.ca> wrote:

>RichA wrote:
>
>> There has to be a point at which increasing the baseline no longer
>> benefits the ability to focus, given average human eyesight.
>> But I remember military binoculars that could have their objective
>> lenses separated by up to 2 feet.
>
>Range finders for artillery had to be accurate well beyond the
>hyperfocal of the lens to determine distance accurately (at least that's
>what I assume you're referring to). So a stereo rangefinding solution
>with a wide baseline is desirable.
>
>For a rangefinder camera, if my assumptions are correct, it would only
>need rangefinding accuracy up to a little beyond the hyperfocal distance
>for the largest aperture of the longest lens in the collection for the
>camera. The longest lens I can find for Leica M is 180mm f/2.8 so that
>comes to a little over 460 meters (for 0.025 CoC).
>
>It may all 'wash' out in the design of the focus coupling to the lens, I
>really have no idea.
>
>Cheers,
>Alan.

What is the benefit of a rangefinder? In the days of film only,
they offered a pretty silent means of getting pictures, no mirror
and soft shutters.
-Rich
Anonymous
May 18, 2005 1:50:49 PM

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

RichA wrote:
> What is the benefit of a rangefinder? In the days of film only,
> they offered a pretty silent means of getting pictures, no mirror
> and soft shutters.

Smaller simpler lenses, fast sure focus in low light
conditions with wide/normal lenses, bright direct-vision
viewfinder - these are the usual advantages that get quoted.
In use each has its own strengths and weaknesses, I still
use both.

--
Regards

John Bean
Anonymous
May 18, 2005 1:54:14 PM

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

RichA wrote:

> What is the benefit of a rangefinder? In the days of film only,
> they offered a pretty silent means of getting pictures, no mirror
> and soft shutters.

-viewfinder is relatively bright (no mirror, no prism, less optics)
allows shooting/focus in fairly low light.

-quiet

-very short shutter delay
(about 6ms for the M6 v. 50 - 100 ms typical for SLR's)

-compact

-advantages in lens design being closer to the film plane (not really
sure about this one).

The various disadvantages include parallax (a real bother the closer the
subject), lack of magnfication in viewfinder according to focal length,
lack of long telephoto lenses, inability to do macro effectively,
forgetting-the-lens-cap and others. I'm not sure about various possible
metering issues. Cameras like the M6 have relatively low fastest
shutter speeds.

Cheers,
Alan.



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Anonymous
May 21, 2005 2:31:23 AM

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

On Wed, 18 May 2005 09:54:14 -0400, Alan Browne
<alan.browne@freelunchVideotron.ca> wrote:

>RichA wrote:
>
>> What is the benefit of a rangefinder? In the days of film only,
>> they offered a pretty silent means of getting pictures, no mirror
>> and soft shutters.
>
>-viewfinder is relatively bright (no mirror, no prism, less optics)
>allows shooting/focus in fairly low light.

Rangerfinders do have mirrors or prisms. How do you thing you get the
two images and then merge them?

Take a look at how they work.

http://www.photozone.de/3Technology/camtec2.htm


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

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my testimony. The events I have recorded should
not be forgotten and must not be repeated."

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