Talk:Single-lens reflex camera

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[edit] Pentaprism?

In the diagram the light path through the roof pentaprism is shown in simplified form. In fact an odd number of reflections are required to rectify the image on the ground glass screen. The first reflection from the moving mirror requires an additional three reflections inside the prism. Two only are shown.

There's not a single diagram in this page. Does this paragraph make any sense? I have commented it out (using HTML tags). If anyone thinks it is one of the "Advantages" of SLRs (yes, it was listed there), then please clarify the text before placing it back.

[edit] Uncategorized chat

SLR cameras also avoid the difficulty of parallax in close-up photography.

I personally own a SLR (Nikon FM2),have read the Nat'l Geographic Field Guide, and have a tickling in the back of my mind--can almost remember what that would mean, but not quite. So I'm certain that the average person who reads this article will also not know what it means. --KQ 17:08 Sep 5, 2002 (PDT)

In fact, we should include an article on rangefinder cameras, unfortunatlly my english is too poor.

I can not remember how parallax comes into play on other cameras in closeups - I guess I should dig out my Field Guide and see if I can clarify it myself - but I wanted to be certain that I understood. --KQ

Too make it simple, what you see in the finder is not what you get on the film. The problem has no importance if the subjet is 1.5 m away or more but became more and more critical the closer you get.

In the 50's SLR camera like exakta we're tricky to use and were mainly used for macro while press photographer used mainly rangefinder camera.

by the way the rangefinder is also a system based on parallax....

The problem is that, from slightly different positions, objects are in diferent angular positions (close on eye, the the other). In a SLR camera you see what you get, from the same position: no angular difference, in a viewfinder camera, the viewfinder and lense are a bit appart from each other: objects are in different angular positions, for close object, that could mean the difference between being in and out the picture.AstroNomer 17:36 Sep 5, 2002 (PDT)

Ah. Thanks, both, for the explanations.  :-) --KQ
This ofc applies as much to unwanted objects as wanted objects. For example if you put your finger over the lens on a viewfinder camera you won't notice until the pictures are developed! Plugwash 19:53, 2 March 2006 (UTC)

NOTE: The image showing the principle of the SLR is wrong, I'm afraid:

  • To get the image correct wrt mirroring, the light path in the pentaprim is like a "4".
  • The mirror is significantly shorter.
  • The focussing screen is not shown.
  • The three light beams appears not to be influenced by the lenses(!)

Egil 12:16 Jan 28, 2003 (UTC)

I've now made a new drawing which is more correct.

Egil 19:08 Apr 26, 2003 (UTC)

Anon: I think the image still needs improvement. The light is shown as a broad area which collapses to a single ray by the time it gets to the film or eye, which isn't quite true (IIRC). Also, by having the light look like a single ray bouncing around in the pentaprism, you don't show why a pentaprism is necessary. The lens inverts the image, no? (Also not shown.) I'd suggest either using 1 or 2 single rays the whole way through (perhaps one on-axis and one off-axis, of different colors), or using a broad swatch of light all the way through, being flipped by the lens.

--- The Minolta SRT 101 is the first SLR with TTL measure at full aperture, thus it established the standard layout for semi-automatic TTL cameras. Ericd 10:29, 11 Aug 2004 (UTC)

Re SRT-101, that is a pretty well qualified achievement. There are hundreds of cameras with similarly deeply qualified achievements. I don't think it is on the same level with e.g. First SLR system (Nikon F), First "modern" SLR (Pentax), First autofocus SLR (Maxxum 7000). Icd 06:00, Aug 12, 2004 (UTC)

If you had ever used a SLR with stop-down metering you should know that it's a major improvement on SLR. It's at the same level as Pentax achievements : TTL metering and automatic mirror return. Ericd 09:19, 12 Aug 2004 (UTC)

I believe the Canon AE-1, manufactured in 1978, is regarded as a relatively groundbreaking SLR, would that be worth adding to the selection? My source for the information is http://www.mir.com.my/rb/photography/companies/canon/fdresources/SLRs/ae1/index.htm which I believe to be a reliable one, as it covers a wide range of cameras by different manufacturers. The reason for inclusion that I got from the page was essentially "The Canon AE-1 was the first 35mm SLR camera to be controlled solely via a built-in Central Processing Unit (CPU) and made SLR photography avaialble to beginners and amateurs at a reasonable prices". Worth mentioning? 59.167.142.149 08:24, 11 November 2005 (UTC)

Oh forgot to log in.. the above was me. He who says zonk 08:26, 11 November 2005 (UTC)

Question: Difficulty in constructing wide-angle lenses because of the space-consuming mirror movement.

My question is: Wouldn't a telephoto lens require more space due to its greater focal length, than a wide-angle lens (whose focal length would be smaller)? Isn't the article's comment reversed on this? (Or am i missing something here?)

This is right. The problem is that at infinite focus the center of the lens should be at a distance of the film plane that is equal to the focal length. This mean that a 100 mm telephoto will have its center at 100 mm from the film while a 28 mm wide angle will at 28 mm only this doesn't leave enougth space for a moving mirror that should be around 24x36mm for a 35mm camera. For illustration have look at http://cameras.alfredklomp.com/jupiter12/ the Jupiter-12 is a very basic WA design for non-SLR camera and look how deep the rear element goes into the camera. In the fifties they were no WA for 35mm SLR while 35mm were alvailable for Leica. The solution is to use a retrofocus lens. This design allow the lens to have a distance from the film that is longer that its focal length, it's like two lens packed the first one forms the WA image and the second focuses the first image on the film. Obviously this is complex design thus expansive and prone to more aberrations. Retrofocus designs are sometimes called "inverted telephoto", because you can roughly reverse the design to build short (I mean physical size) telephoto lenses. For instance you may find a bit bulky a 300mm lens that will at least 300mm long with a basic design. A telephoto design will allow to build a lens shorter than 300mm. Ericd 00:53, 25 Jun 2005 (UTC)


[edit] K1000

The K1000 is a notable camera, IMO, because (a) it started the K mount and (b) it was very successful in terms of sales. Yes, it didn't introduce any real technical advances, but that's not in my opinion the only measure of notability. Comments? Matthew Brown 09:36, 17 November 2005 (UTC)

[edit] Impotance of SLR camera in this digital era.

As i know the advantage of SLR camera is for able to see the exact sean through eye piece (avoids parlox error). Now all digital cameras shows the exact picture on the screen. Then still what is the importance of the SLR camera's. Please some one clarify.

A digicam screen eats batteries and is very hard to use in bright sunlight. Also the resoloution of the small LCD display isn't sufficiant to use for anything more than selecting the frame area (can't really be used to manually focus or to check the autofocus has got it right). I have a screen only digicam and its pretty horrible to use compared to a camera with a traditional viewfinder. Plugwash 00:29, 26 February 2006 (UTC)

[edit] Rangefinder vs. Reflex

I don't know how to include this but when a rangefinder gets autofocus it lost its rangefinder and become a basic viewfinder camera... See Konica Hexar AF or Contax G. Ericd 15:54, 6 December 2005 (UTC)

[edit] Is the cross-section correct?

I contribute mainly to the french wikipedia and worked recently on the french version of this article. It uses the same cross-section picture (as do many other international Wikipedia's). Recently, someone stated that this picture is wrong, that it shows a wrong number of reflections in the prism. Personnaly, I seriously doubt it and would rather think that the US, DE (etc...) articles are correct. Only this user reverts every time I remove his comment. So I guess I need some extra sources to convince him (or maybe he's right after all, who knows?). I made some search but found nothing except copies of this US wikipedia article on other websites...
Does someone may an extra source/reference then?
The only (small) critic I have against this picture is that it doesn't show inverted rays after the lens, but it's not treally the point of this article to explain the way lenses work. As a side note, I got the same problem (with the same user) with the picture illustrating a roof pentaprism, so I asked a similar question in the "Talk" page of this article. --Jérémie A. 13:12, 28 February 2006 (UTC)

[edit] Aperature

The diagram does not show the aperature. It would be nice if it was included.

Erland Lewin 14:33, 28 February 2006 (UTC)

The aperture is irrelevant to the concept being shown, and adding an iris diaphragm would be an unnecessary complication. -- Hoary 11:16, 2 March 2006 (UTC)

[edit] The history: Is it too simple? Is it even correct?

This page reminds me of some innovative SLR cameras I'd known of (including the Rectaflex, Miranda, and Zunow), as well as some I didn't: notably the Gamma Duflex of 1947, "with instant return mirror".

Some things claimed in this Wikipedia article to be firsts don't seem to be firsts. I hesitate to edit, because I suspect that a number of the firsts that predate the "firsts" in the article might need qualification with "however" (and not only "however, it was not commercially successful" but also "however, it was unreliable and easily broke down" or "however, it only functioned when combined with XYZ / when the photographer remembered to ABC").

An example is this paragraph:

Through-the-lens (TTL) light metering came to the SLR in the early 1960s, with 1962's Topcon RE Super (spot metering) and 1964's Pentax Spotmatic (center-weighted average metering). Auto-exposure was next, introduced by Pentax in 1971's Electro Spotmatic and popularised with 1976's Canon AE-1 Program, one of the best-selling cameras of all time. Full program auto-exposure soon followed. The 1970s and 1980s saw steadily increasing use of electronics, automation and miniaturization, including integrated motor driven film advance with the Konica FS-1 in 1979, and motor rewind functions.

I don't know the real answer, but I do know the Konica AutoReflex of 1965 was a shutter priority autoexposure camera, and the AutoReflex T of 1967 was a TTL aperature priority autoexposure camera, thus falsifying the statement that "Auto-exposure was next, introduced by Pentax in 1971's Electro Spotmatic." --Kperegoy 02:34, 12 March 2007 (UTC)

There is certainly room for discussing the first critically/commercially successful examples of this or that (whether this success was a matter of particularly good design, marketing clout, low price, or some combination thereof). However, commercial success isn't all: though the Zunow clearly wasn't a commercial success (and for all I know may have been what bankrupted the company), it did seem to have an impact. -- Hoary 11:16, 2 March 2006 (UTC)

I have serious doubts about parts of the history. This is partly because I have found it very difficult to get histories of photographic equipment that are not single-brand histories. Single-brand histories tend to trumpet the achievements of that brand, and quite often make inaccurate statements, or at least statements that (as you said) need to be qualified. Quite often, when you look into 'first', it turns out to be 'first commercially successful' or 'first widely used', or 'first that really worked well'.
Thus, if anyone has any idea of general photographic history works that will help - feel free! Matthew Brown (Morven) (T:C) 06:17, 29 August 2006 (UTC)
Annoyingly, on looking through this article, the history that WAS here has been severely mangled and chopped to bits since I last worked on this article. Editors: if you have problems with the sourcing or NPOV of text, you should question it on the talk page, or if you find it really bad, move it to the talk page at least. The page now misses many critical parts of SLR history, including glossing over the MAJOR impact of the Nikon F - the camera that took professional photography by storm and pretty much wiped out the rangefinder camera as the mainstream 35mm type - and the contributions to the autofocus SLR by Minolta and Canon are now completely gone. Canon's utter dominance from the late '80s on of the professional sports and event photography market is also completely gone. Matthew Brown (Morven) (T:C) 06:55, 29 August 2006 (UTC)

[edit] SLR-like

What's the difference between SLRs and SLR-like cameras? All that I can tell is that SLRs don't come with a lens (?), and SLR-likes do. 71.250.17.62 02:01, 20 June 2006 (UTC)

found some information at DSLR 71.250.17.62 15:49, 21 June 2006 (UTC)

[edit] Filters

I have just removed this very recent addition: Filters that attach to the end of the lens only increase the options for the photographer. The most commonly used is a UV filter, which is extremely useful for reducing the harshness of sunlight in a picture.

The first half is true, and also true of various alternatives to the SLR. (Indeed, it could be argued that a red filter is a major pain with an SLR but a breeze with a rangefinder camera.) The second half is simply untrue. -- Hoary 13:22, 12 October 2006 (UTC)

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[edit] Guillemets

Respectively questioning the usage of the double arrows around the word <<intelligent>> in the first sentence of the “Autofocus” section. Is there a meaning to this or just an oversight? Just a Wiki-rookie trying to help! Bigwig77 01:52, 2 January 2007 (UTC)

Thanks for catching that. I've replaced the guillemets with double quotation marks. A non-native English speaker probably added them by mistake. --Imroy 05:02, 2 January 2007 (UTC)
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