Talk:Shutter (photography)

Early discussion

Can a subject matter expert please add to this entry? I'd like to understand why central shutters do not expose the center of the frame longer than the edges.

The article does say, "[i]deally the opening and closing are instantaneous..." The current article correctly explains the reasons this is true, and also correctly does not mention anything about exposing the central parts of the image more than the periphery. I would like to understand, though, the reasons behind why central shutters do not overexpose the central portion of an image. Severoon 22:36, 21 February 2006 (UTC)

I'm not an expert, but I do work on cameras, so I know something about them. First of all, a terminology problem: nobody calls them "central shutters". These shutters are almost always referred to as leaf shutters, so that's the term I'll use.

It's true that, ideally, the shutter opens and closes "instantaneously". Obviously, this cannot happen in the real world. But it turns out that, for all practical purposes, they really do work nearly instantaneously; hence, the edges are not underexposed as you might expect.

Leaf shutters are nearly identical in their basic design and operation. The shutter blades are operated by small pins attached to the blades, which run in holes or grooves in a ring around the outside of the shutter opening. When the ring is turned a very small amount, the blades open. Since the distance between the blade pivot and the operating pin is so short, this works as a lever, so the working part of the blade, which is much longer, is really whipped open (and closed) quite fast. They seem to open and close instantaneously, with no perceptible "irising". Pretty fascinating stuff, actually.

In fact, leaf shutters are famously much less prone to uneven exposure problems than focal-plane shutters. In a FP shutter, if the curtains don't travel at pretty much identical speeds, you get problems with "fade", where one edge of the frame is significantly more exposed than the other edge (in the direction of curtain travel). I've seen, and had to fix, this problem with several of my own cameras. ==ILike2BeAnonymous 07:35, 22 April 2006 (UTC)

Hmm...I think you've presented the misunderstanding I was asking someone to address in the article. Diaphragm shutters (the iris type comprised of several curved blades) do not open or close, for all intents and purposes, instantaneously. The time it takes this kind of shutter to open and close is not at all instantaneous compared to the fastest shutter speed available on a given camera. In fact, the limiting factor on shutter speed is indeed the travel speed of the leaf shutter itself...you can bet that at the fastest available shutter speed, the relative amount of time the shutter spends in transit is not negligible at all.

I'm asking for someone to address this very topic in the article because of the misconception you express. Even a very slowly travellng diaphragm shutter would not, as you seem to indicate, underexpose the edges. If this were true, then setting small apertures would only expose the central region of the frame, right? Think about it, and you'll understand...you take a shot with an aperture of f/2 and the entire frame is evenly exposed, you take the same shot at f/64 and the entire frame is still evenly exposed despite the iris being only a tiny fraction of its size at f/2. This means when you take the shot at f/2, as the shutter opens and travels through f/64, f/32, etc, at every position along the way light is transmitting to every part of the image frame evenly.

Incidentally, a leaf shutter is indeed a type of central shutter, but it's not the iris type you're talking about—that's a diaphragm shutter. Click the links to learn more. Severoon 10:22, 28 April 2006 (UTC)

Let me respond to your comments. First of all, to get the easy subject out of the way: the last thing you wrote deals with semantics. Yes, all these shutters are indeed types of central shutters. But I stand by my assertion that almost all central shutters are what are commonly referred to as leaf shutters (more properly "diaphragm shutters" as you point out). By this, I mean bladed shutters with at least 3 blades, which form an iris in opening and closing. This covers the vast majority of in-lens shutters (Compur, Pronto, Prontor, Copal, Kodak, Vario, etc.). A very few earlier shutters, like the Derval, used only two blades, so they were not diaphragm shutters, but these were only used on cheaper shutters with three speeds (generally 1/25, 1/50 and 1/100), or what someone once told me are "shutters where you can pretend there are three different speeds", as they're notoriously inexact. And of course some really cheap cameras (like the 120 and 620 fixed-focus one-speed jobs) used one single shutter plate.

With that out of the way; so you're saying, basically, that leaf (diaphragm) shutters are inherently self-correcting so far as evenness of exposure over the field goes, correct? I'm not disputing that, just checking.

If so, you may be correct. But it seems to me that this would depend on the proportion of time the shutter spends fully open versus the time it takes to open; correct? In other words, if the shutter takes a relatively longer time to open than it does staying open, wouldn't the center tend to be overexposed?

But since in the real world photographs taken with leaf shutters are, from my experience, always evenly exposed for all practical purposes, maybe we should just leave things as you have put them. Which, unfortunately, means your original question is still unanswered.

In my search for material on the web, the best I've been able to come up with is this page on Compur shutter operation, from Rick Oleson's inestimable camera site (worth digging around in if you haven't seen it before). But he doesn't talk about the matter of blade speed, exposure evenness, etc.

I'm not saying that diaphragm shutters are self-correcting—I'm saying they need no correcting because light that passes through the iris, regardless of the diameter, is spread evenly over the entire frame. The size of the iris affects depth of field, not coverage over the frame. As I said, just think about the effect of changing f-stops on the resulting image...no matter how small the aperture, the light falls evenly on the frame. Only dof is affected. Severoon 09:15, 1 May 2006 (UTC)

Bingo! Epiphany time: now I see what you mean. Of course; since it's not at the focal plane, it acts as an iris. So this ought to go into the appropriate articles, no? ==ILike2BeAnonymous 19:05, 1 May 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)

Some interesting examples of shutters

While disambiguating links to shutter, I came across some interesting uses of the word shutter, uses that might be related to photographic shutters:

• Movie projector#Shutter - are these similar but different to shutters on a camera? One lets light in, and the other lets light out!
• Tachistoscope - the shutter on this device works a lot like the shutter on a camera in the sense that it is a one-use opening and closing of the shutter (as opposed to a continuous opening and shutting in a projector. But the light is still being emitted, rather than admitted. So should this article link to Movie projector#Shutter or shutter (photography)?

So are these projector shutters different from photographic shutters? And in what way? And should this be mentioned in the relevant articles? Carcharoth 00:28, 20 May 2006 (UTC)

Movie projector shutters are the same as camera shutters: they open an aperture for a certain time (and, in the case of the movie projector, at a certain time). Almost all movie shutters (cameras and projectors) are rotary (as are some peculiar still-camera shutters, notably the Univex Mercury and Olympus Pen F half-frame 35mm cameras).

By the way, you have it wrong: the purpose of a shutter on a camera (as well as the purpose of a door to a darkroom) is to keep the dark from leaking out. ==ILike2BeAnonymous 00:47, 20 May 2006 (UTC)

"Keep the dark from leaking out" - classic!! Next thing you'll be telling me the world turned colour in the 1930s... :-) Carcharoth 01:05, 20 May 2006 (UTC)

Another example of a shutter is at Signal lamp. Does this sort of shutter count as a photographic shutter? I think this is now broadening to have a general shutter (optical) terminology, with different sorts of optical shutters being used in projectors (with a signal lamp being a sort of projector) and cameras. Carcharoth 01:24, 20 May 2006 (UTC)

Since we're on the subject of oddball shutters, here are some more:

• Of all the cameras I own, the one with the weirdest shutter has to be my Exa, one of the original 35mm SLRs. Hard to describe what type of shutter it is, actually. Like a lot of early SLRs, this camera is "dark" (can't view through the lens) until the shutter is cocked. The shutter consists of the mirror board plus another part that swings horizontally below the mirror. Not a focal-plane shutter, not a leaf shutter. (Speeds up to 1/150 sec.)
• Another notable strange shutter, sort of, is the Packard shutter. While this is really just a simple 2-leaf shutter, what's interesting about these is how they're used. Their purpose in life is to give shutter-ness to lenses with no shutters, like the lenses formerly used in copy cameras and other graphic-arts uses, for large-format cameras. They're extremely simple: they're pneumatically operated with a squeeze bulb, and some only have a "bulb" setting (stays open as long as the bulb is squeezed), while others have an optional "instantaneous" setting which gives a (very approximate) 1/25 sec. or so exposure. They can be placed either behind the lens or even in front of it, depending on the camera architecture. See here and here for more info (the second has contributions by the inestimable Richard Knoppow, photography guru who also posts to several Usenet newsgroups on photographic subjects).

I'm planning to add content about the mirror-as-shutter as used in the Exa. Does it belong in the focal-plane section, or in its own? It has the same advantage as the focal-plane shutter (easy to change lenses), most of the disadvantages, and one disadvantages of its own: limited top speed, as noted in the comment just above, although in theory that's not a disadvantage of the idea, but only of its implementation, as R&D of mirror-as-shutter designs probably stopped in the early 50s. (Note that the above is just commentary; it is not the text that I am planning to add.) Please let me know here what you think of this addition. Rochkind (talk) 17:56, 19 June 2009 (UTC)

In addition, it might be intereresting to point out the various mechanisms used internally by shutters. There are basically two types: mechanical and pneumatic. Mechanical shutters use levers, pawls, etc., to give certain timings, and clockwork delay mechanisms with buzzing pallets for "slow" speeds (anything slower than about 1/25 sec.). Pneumatic shutters (which are obsolete) use a piston and cylinder arrangement for slow speeds, like in the old Compound shutters. And of course, there are those newfangled electronic critters. ==ILike2BeAnonymous 03:10, 20 May 2006 (UTC)

Intermittent mechanism

I added a link to intermittent mechanism (or motion) from the movie projector bit at the bottom of the article. It sounds like the shutter and film bits of the projector both use intermittent mechanisms, but I'd be grateful if someone could check. Carcharoth 01:16, 20 May 2006 (UTC)

The film-moving mechanism (claw) is intermittent, but the shutter rotates continuously. The claw moves the next frame into place, and while it is stationary, the shutter opens and closes, 2 or 3 times. ==ILike2BeAnonymous 02:49, 20 May 2006 (UTC)

Shutter Lag

Would this be an appropriate place for a discussion of shutter lag - the delay between pressing the shutter release and the damn thing actually going off? This seems to be more relevant than ever in this brave new world of digital imaging! 88.110.45.118 22:50, 25 May 2006 (UTC)

I would be say no, but then, I'm a Luddite who still uses real cameras (ones which use film). I'm curious: just how long a delay are we talking about here? Half a second? More? I guess it could be relevant to digicams. ==ILike2BeAnonymous 23:11, 25 May 2006 (UTC)

It is hard to find figures, one would think that users would be more concerned. Compact digital cameras are said to be anything up to 1.5 seconds! Digital SLR's stated of the order of 100 - 150 milliseconds but my subjective feeling is that they are always slower than proper SLR's, whether electronically controlled [F4], or mechanical [FM2 or OM-1]. To my great surprise I have just found a figure of 200ms for the MD-12 drive on the FM-2. Subjectivity again, but over thousands of images taken with a Nikon D70, my wastage rate in demanding situations is far higher than it would be with a film camera. Moel Faban 23:53, 25 May 2006 (UTC)

Added the section. Go ahead and flesh it out. ==ILike2BeAnonymous 00:03, 26 May 2006 (UTC)

I see no reason whatsoever why a dSLR would by nature have more shutter lag than a film SLR. If you have any compelling evidence or reasoning behind this statement, let me know because I'd be interested to see what I'm missing. I shoot a Canon 30D right now, and from what I understand, what little (unnoticable to me) lag there is is due to the mirror flipping up and out of the way, which is exactly the same in a 35mm film camera. Well, not exactly, actually...since the 30D has an APS-C sized sensor, the mirror required to block it is smaller and therefore likely lighter than the one required in a 35mm film camera. Therefore, if anything, I'd expect it to lag less. Severoon 23:31, 27 June 2006 (UTC)

"....on the order of hundreds of milliseconds..." That's rather opaque! DMCer 05:43, 1 February 2007 (UTC)

Shutter lag has unfortunately ingrained itself into the common language even tho in most cases it has nothing to do with the shutter. Shutter lag is in most cases actually Auto-Focus lag. Since most cameras will not activate the shutter until after AF is confirmed the delay appears real. Smaller less expensive cameras suffer worse simply because their AF is less sensitive and needs more contrast to work properly. Low light, low contrast situations make lag worse in any camera. Turning off AF is the solution, but that's hardly viable in most situations where lag is an issue to begin with, and most smaller cameras don't give you the option anyway. I'm going to add words to this effect in the main article. Ken (talk) 18:23, 24 October 2012 (UTC)

It's the lag from pushing the button to the shutter opening, no matter what the cause. Dicklyon (talk) 20:51, 24 October 2012 (UTC)

quite true yet unfortunate. the gist of my point is that the name tends to keep folks from coming to the proper solutions (see Severoon's comment above). Corrective actions involving more light or manual focus will have better results as they address the root cause: AF delays. the workings and limitations of the actual shutter mechanism have virtually nothing to do with it, other than to give it a name and misdirect those who might try to avoid it somehow. cheers Ken (talk) 21:07, 11 December 2012 (UTC)

Merge?

Since diaphragm shutter got merged into leaf shutter, perhaps it would make more sense to merge the combined article into this article and deal with it all in one place.--Srleffler 03:52, 12 December 2006 (UTC)

Support. Yes, they're too narrow to be separate. Dicklyon 05:10, 12 December 2006 (UTC)

Support, indeed. Scoo 07:18, 13 December 2006 (UTC)

Disagree. On the contrary, the Shutter article should explain what a shutter does and where it goes, with details on the various mechanisms in separate articles. Pol098 22:45, 2 April 2007 (UTC)

Thanks for your alternate view. However, since the articles are all so short, does this really make sense? Wouldn't subsections be the more conventional way to organize it? We pretty much decided to do the merge, hearing no dissent, but nobody has gotten around to it. Dicklyon 23:50, 2 April 2007 (UTC)

In which case you'll need to undo stuff I deleted from shutter which was duplicated in leaf shutter (as far as I remember). I've made a number of changes to shutter, leaf s, and central s. I maintain my preference for separate articles, but appear to be in the minority. Pol098 20:13, 5 April 2007 (UTC)

Disagree too. The real alternative to separate articles is one which combines Leaf shutter, Focal plane shutter, Rotary disc shutter and Kerr cell shutter. That may get too long. --SE16 09:31, 23 April 2007 (UTC)

There's not much danger of it getting long, as all the articles are very short. Dicklyon 18:10, 23 April 2007 (UTC)

So who's going to do this? Dicklyon 21:13, 28 January 2007 (UTC)

Dunno; probably not me. But I think I can offer something useful: a taxonomy of shutters:

• Leaf shutter (aka "diaphragm" or "central" shutter)
  • The only subtypes here would be on account of different numbers of blades (2 - n).
• Focal-plane shutter
  • Horizontal traveling
  • Vertical traveling
• Rotary (disc) shutter
  • Motion-picture camera
  • Still camera (e.g., Univex/Olympus)

I have no idea what a "Kerr cell" shutter is. Where would that fit into this taxonomy?

In any case, I offer this as a potential guide to organizing the shutter articles here.

By the way, my take is that a single article covering all types would be preferable to a bunch of small, scattered articles. All shutter types could easily be covered in a concise article of reasonable length. +ILike2BeAnonymous 18:27, 23 April 2007 (UTC)

More merge

Let's also merge central shutter here. There's not much in it. Dicklyon 23:28, 21 September 2007 (UTC)

Support - for all the reasons already presented

Badly Bradley 18:12, 28 October 2007 (UTC)

Sad Personal Biases

It's pretty sad when the author(s) of this article haven't educated themselves enough to know the phenomenal benefits of a well-designed leaf-shutter mechanism as opposed to the slow and antiquated focal-plane shutter mechanism. I guess they are trying to justify the expense of their D/SLR cameras.

It is possible to take high-speed exposures up to 1/40,000 of a second (and possibly faster) with a point and shoot camera's leaf/diaphragm-shutter. 1/40,000th of a second is not a typo for 1/4,000th. As well as having FULL-FRAME exposure at those speeds with flash units firing shorter than 1/224,000th of a second. Also with virtually no shutter lag (45ms), and no problems from focal-plane-shutter distortions of high-speed subjects. http://images.wikia.com/chdk/images//4/46/Focalplane_shutter_distortions.jpg

See http://chdk.wikia.com/wiki/CameraFeatures

Your ignorant and inexperienced biases are shouting off your page loud and clear. —Preceding unsigned comment added by 64.61.220.26 (talk • contribs)

It's pretty sad when a new inexperienced editor violates WP:NPA instead of helping to improve an article. Dicklyon (talk) 06:27, 4 September 2008 (UTC)

Well that's just silly to do that. Because then when I corrected all your errors you'd just hit the undo button relentlessly to try to reinstate your ignorant views and argue about it for weeks. I've played that game before with other Wiki editors. Your personal biases are the truth to you. I just thought I'd let you know you're wrong so you can do what you usually do. Complain about the messenger instead of you correcting all your own errors and misinformation.

(Correct information added, as requested, and guess what? The dweeb undid all the FACTS about shutters!)

LOL!!!!!!!! Just as I suspected. YOU CAN'T HANDLE THE TRUTH! You'd rather advertise your FALSE biases, PROVEN WRONG, rather than let the truth be known by anyone. LOL!!!!!!!!!! You wiki fucks are all the same! Anyone wanting to know the truth about focal-plane shutters now only has to click on this link: http://en.wikipedia.org/w/index.php?title=Shutter_(photography)&diff=237215890&oldid=237215731

I reverted to before the inclusion of strikeout style in the article, since that's not appropriate. I haven't made any judgement on the content of what you wrote. So get over yourself, learn how to edit in article space, and get back to trying to improve wikipedia. Dicklyon (talk) 05:41, 9 September 2008 (UTC)

Sad Peronal Bias II

As the original author of the leaf shutter article and the original drawer of the leaf shutter and focal plane curtain shutter diagrams (many years ago), I'm dismayed and disappointed with the way this article has gone. I'd be flattered that my original drawings are still there (albeit not always helped by editing of one sort or another) but I expected somone would have done some good original work that improved on my poor beginning. This pastiche though is just confusing and contains so much mis-information and rubbish it's upsetting, to say the least.

At least half of the article is just rubbish eg: Special flashbulbs were designed in a slow-burn style where the light would reach full intensity, and then remain at that intensity to wait for the slow focal-plane shutter to expose the full film frame. What utter rubbish, and exactly the opposite of what actually happened. The slow ignition time of the flash bulbs required that the flash be fired before the shutter was opened. There's also silly claims in there of central shutters being capable of 1/40,000 second. Your digital marvel can do some great things, but moving a mechanism at mach 4 or 5 is not one of them. The author of that statement seems confused about what a shutter is and how it works - digital exposure time is not the same thing as shutter speed in this case.

I'd list all the errata in this article but it's just too depressing. I'm saddened by the realisation that people coming here for information will instead get so much misinformation and outright rubbish instead of the concise article that should be here. I'm a bit of wikepedia fan, and always had faith in the ability of contributors to self-edit. That faith has been severely shaken on reading this article. Chris 211.27.190.162 (talk) 16:36, 24 September 2008 (UTC)

Lots of wikipedia articles are in sad shape, and it's not because of personal biases so much as just not yet attracting the energy of editors willing to do the work to improve it. Your comments do not seem to be the sort that are going to inspire anyone, so jump in and work on it if you want to help. Dicklyon (talk) 21:18, 24 September 2008 (UTC)

I'm saddened that these people replying above aren't even responsible enough to educate themselves to obliterate their own deep levels of ignorance. One needs to only Google for "Focal-plane Flash Bulbs" to know that again you are revealing your sad personal biases, yet again. Causing you to call facts as fiction. You people are just sad and sadder all around. Hint: GO EDUCATE YOURSELVES! At least go buy some REAL cameras so that you are not inventing "facts" out of your pathetic delusional virtual-lives. Here's just one passage from hundreds on the net that describe focal-plane flash bulbs -- "High Speed Synch is like using Focal Plane flash bulbs - once ignited they emitted light for over 1/10th of a second, to ensure that the slit of light allowed by the shutter covered the entire frame." Get over your immature inexperienced biases, you are making yourselves look like the total fools that you are. —Preceding unsigned comment added by 64.61.221.16 (talk) 01:39, 28 October 2008 (UTC)

64, since you edit under a variety of dynamic IP addresses, you're probably not seeing the messages directed to you on your talk pages. You might want to make an account. That would make it easier for us to help you learn how to make your contributions acceptable. I'd be happy to help format up citations to sources or whatever. Dicklyon (talk) 00:06, 27 January 2009 (UTC)