Talk:Diaphragm shutter

Can anyone verify the terminology I've used in this article that describes the diaphragm shutter and the leaf shutter as different kinds of central shutter? I've read a lot of sites that use diaphragm shutter interchangeably with [central shutter], but other sources disambiguate the terms as I have in the article (which I—obviously—believe to be correct). —Severoon 10:25, 24 February 2006 (UTC)

I've edited the article to reclassify things and clarify. The correct taxonomy would be:

• Shutters
  • Leaf shutters
    • Diaphragm shutters (multiple-blade, but this term is rarely used)
    • Two-blade leaf shutters
    • Single leaf shutters
  • Focal-plane shutters
    • Horizontal-travel FP shutters
    • Vertical-travel FP shutters
  • etc.

==ILike2BeAnonymous 18:55, 28 April 2006 (UTC)

Discussion at diaphragm (optics)

There is a discussion at Talk:diaphragm (optics) about various similar terms with separate articles on Wikipedia, and trying to clarify what these terms all mean (from a confused amateur photographer!)... Carcharoth 23:25, 18 May 2006 (UTC)

I think that's a real bad idea to move this shutter confusion into the diagphragm article. I'd say reject the idea of merging with diaphragm, and merge into shutter instead. This obscure old term doesn't deserve its own article. Dicklyon 04:26, 19 May 2006 (UTC)

What is a diaphragm shutter, really?

Has anyone ever seen, used, or heard of one these things? The only mention I can find in a book is in the Focal Encyclopedia of Photography, where there's a stationary diaphragm shutter in the caption of a diagram of a high-speed camera. It looks to me like it works like the slit in a cirkut-type panoramic camera, and that it's near the focal plane, not a central shutter, and not resembling an iris diaphragm at all.

I'd say that unless we can find someone who can write something useful and authoritative about it, we should just flush this article. Dicklyon 15:10, 19 May 2006 (UTC)

I was going to write a much longer response, but in the interest of simplifying rather than producing more smoke to obscure things further, I'll just say that technically speaking, a diaphragm shutter is just a leaf shutter, meaning the standard type with 3 or more leaves, not the two-blade or single-blade variants. They form a diaphragm on opening and closing.

What does that mean? You mean they form an aperture on opening and closing? Do you have any references about diaphragm shutters other than the few I found? Something definitive? Dicklyon 17:45, 20 May 2006 (UTC)

The problem is this: nobody calls them "diaphragm shutters" in the real world. They're called "leaf shutters". Don't believe me? Check real-world sources like eBay (looking for sellers who know what the hell they're talking about, not clueless sellers), or companies like Pacific Rim Camera which regularly deal with cameras with all types of shutters (not digital). So I guess I'm endorsing getting rid of the "diaphragm shutter" article too, and putting the information in other articles. See my taxonomy above for one way this information could (and should, in my view) be apportioned among articles. ==ILike2BeAnonymous 18:56, 19 May 2006 (UTC)

So what is the relationship between leaf and diaphragm shutters? Is one a subset of the other? Or are they just variant terms for the same things? Dicklyon 17:49, 20 May 2006 (UTC)

I would guess, from the usage I've seen, that leaf shutters started off as single-bladed and then double-bladed, and then became multiple-bladed. The single and double bladed ones just move up and down (or round and back for rotary ones) across the aperture contained in a separate diaphragm, but the multiple-bladed leaf shutters, especially with the introduction of curved ends to the blades, were now able to form a near-cicular hole as they opened and then closed again (as a shutter must do). This was effectively imitating the way the iris of eye contracts, with the difference that the iris of the eye cannot close completely. As the iris is also a diaphragm, someone probably thought it would be a good idea to call this "shutter that acts like an iris" a diaphragm shutter. In fact, the term "iris shutter" might have caused less confusion.

And from my (limited) understanding, I now think that the essential difference between a diaphragm and a shutter is that a shutter must at some point cut off the light completely, whereas a diaphragm must always have an aperture. So an iris diaphragm that can't be adjusted to zero aperture will always be just a diaphragm and never a shutter. Converely, if it could be adjusted to zero aperture, it would no longer be a diaphragm, and could be used as a shutter (either slowly as a manual one, or fast as an automatic one). The same arguments apply for a diaphragm shutter - if it could be manually adjusted to different apertures and left open, it could be used as a diaphragm (it would then effectively be an iris diaphragm).

In other words, diaphragms and shutters both developed towards the "iris" model, and the advent of: (a) the iris diaphragm; and (b) multi-bladed leaf shutters (that opened to form circular apertures); meant that the same structures could act as either diaphragm or shutter depending on how they were used.

So, the essential features might be:

• Iris diaphragm - has an aperture formed by multiple blades that can be adjusted between shots to change the aperture, like the iris of an eye. Remains static when a picture is being taken.
• Multi-bladed leaf shutter - resembles an iris diaphragm, but starts from a position of zero aperture and opens and shuts quickly to expose the film. Sometimes called a diaphragm shutter, probably because it can be said to form an aperture when opening, and thus at that point it can technically be described as a diaphragm. It could also be considered an iris diaphragm that has been adapted to be a shutter.

Also, if there was no other diaphragm and aperture in the optical system, then the diaphragm shutter might effectively act as the diaphragm, with the initial opening of the shutter forming the system's aperture (rather than the shutter moving across a separate aperture). Is this actually possible? What would the aperture of such a system be? The maximum the shutter opened to, or the infinitely small initial aperture formed as the shutter began to open?

Finally, with the eye having a diaphragm (iris) and an aperture (pupil), would it be correct to say that the eyelids act as a double-bladed leaf shutter, albeit rather a slow one. I suppose the retina would be the "sensor" (no film here, think CCD). Close your eyes, and then open and close your eyelids quickly - there you go, you've "taken" a picture - transmitted by retina and optic nerve to the brain, for temporary storage and recall from the short-term "memory". Now just imagine if the eye had a rotary disc shutter... I guess we have to do with a sensor (retina) that has a high refresh rate instead. Carcharoth 10:32, 21 May 2006 (UTC)

And in case it helps, here are the first few words of what the EB have to say: [1]. They treat diaphragms and shutters as one topic, which doesn't really seem that helpful to me. Carcharoth 10:49, 21 May 2006 (UTC)

Strange Stargate reference...

While following up "What links here" for leaf shutter, I found a weird Stargate reference. At Iris (Stargate), the iris-like structure was described as being like a leaf shutter, and I changed it to diaphragm shutter. From looking at the pictures on the Stargate page, especially at the GIF of it opening and closing here, can anyone confirm whether I have got this correct?

I think that's a terrible idea. Here we are struggling to find anyone who knows what the disused term diaphragm shutter really means, and you go and link something to it that may or may not be one, substituting a largely unknown disused term for a commonly understood term. As far as I know, there is no optical shutter that works like an iris diaphragm as shown in your stargate picture. I'd call it an iris diaphragm instead, and get rid of the shutter refererence altogether, since it doesn't resemble any known shutter. Dicklyon 17:54, 20 May 2006 (UTC)

OK, maybe I was too quick to jump in there. But I'd disagree that that structure resembles an iris diaphragm. It opens from, and closes to, zero aperture. To my mind that disqualifies it from being a diaphragm, unless you allow diaphragms to have zero aperture. Also, it opens and closes - that seems to me more like a shutter (moves during use) than an adjustable diaphragm (only moves when being adjusted between use). Carcharoth 10:55, 21 May 2006 (UTC)

Why do you think they call it the iris? And can you show me any example or reference of an iris that closes all the way to act as a shutter? I don't think so; it's entirely hypothetical that that's what a diaphragm shutter is; none of the actual things I've seen referred to as diaphragm shutters resemble an iris diaphragm like the iris stargate does. Dicklyon 03:38, 25 May 2006 (UTC)

And regarding the 'shutter taxonomy' above, that has made things a lot clearer for me. Thanks. I think leaf shutter currently has an illustration showing a single-leaf, spring-loaded shutter. But if a diaphragm shutter is simply a multi-bladed leaf shutter, then the article should be merged there insteaed. I'll go and change the tags. Carcharoth 22:46, 19 May 2006 (UTC)

Thank you, as I'm too lazy right now to do it. But it's true: all shutters which use leaves to block the aperture are leaf shutters, whether they have 1 leaf or 7. ==ILike2BeAnonymous 23:37, 19 May 2006 (UTC)

Argus C3

A diaphragm shutter is mentioned at Argus C3 if that helps... Carcharoth 11:31, 20 May 2006 (UTC)

Interesting. And it's NOT a central shutter in that instance. Dicklyon 17:30, 20 May 2006 (UTC)

Yes, but again, nobody (practically speaking) in the photographic world uses the term "diaphragm shutter" to refer to the "brick"; they'd call it a leaf shutter. Check around the Web to verify this. (Same with the term "central shutter"; it's an overly-pendantic term which I doubt is even used in McKeown's.) ==ILike2BeAnonymous 18:12, 20 May 2006 (UTC)

Some more links

I found this about leaf shutters. But that is just another wiki site. A far more helpful, in fact a very helpful PDF document overview of camera shutters is here: Google HTML conversion of Andrew Glassner’s Notebook, link to PDF version of Andrew Glassner’s Notebook. The latter PDF link includes diagrams that should clear up any confusion. Carcharoth 11:10, 21 May 2006 (UTC)

And a link to Glassner's columns: [2]. I'll try to dig out the one about shutters and link to it from the shutter (photography) article. Carcharoth 11:16, 21 May 2006 (UTC)

Oh. Those webpages are only summaries of the columns. For all the columns, you have to get the books (which I might do). It is the May 1999 column here, called "An Open and Shut Case", but for the text see the PDF link above. Carcharoth 11:20, 21 May 2006 (UTC)