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Speed is normally measured as something per second. Taka 20:14, 14 September 2006 (UTC) reply

Shutter speed is the conventional misnomer for exposure time; it's measured in seconds. Dicklyon 00:45, 8 June 2007 (UTC) reply

The terminology is confusing. I would expect speed and time to have an inverse relationship - when something is done with more speed (faster), it takes less time and vice versa. If shutter speed is a misnomer as Dicklyon says, it should be noted and explained in the article. -- Imroy 14:14, 23 August 2007 (UTC) reply

What I say is irrelevant. Find a book that talks about it if you want to put it in the article. You can't just go around saying things are confusing in an encyclopedia. Dicklyon 01:00, 28 August 2007 (UTC) reply

Also just to note that speed normally measures distance divided by time. Since this isn't actually a measurement of distance, it fails the "normally" qualifier anyway. Girolamo Savonarola 07:44, 2 September 2007 (UTC) reply

I'll have a crack at this. Red herrings aside:

• The shutter speed is the time taken for the shutter to open and close.
• Shutter speed is the time set for the shutter to remain open after pressing the shutter release.
• ... to travel to the open position and return to the closed position.
  • We have time, and distance if you like.
  • 1/100 (a hundreth part of a) second is faster(longer) than 1 (one) second. The time it takes to travel ...
  • This could be viewed as a cycle, and the time taken to complete it is the speed.

Hope I'm helping to find a simple explanation for the apparent confusion. I made a start by editing the other side

← Cygnis insignis 15:56, 2 September 2007 (UTC) reply

Sure, that's an OK explanation of speed. It's not how it really works, though. The shutter mechanisms generally snap open at a constant fast speed, then wait, then snap shut at a constant fast speed. So taking "speed" literally as distance per time is misleading, and not what's intended. There's also lens speed and film speed, where no such strained analogy would be attempted. Dicklyon 16:01, 2 September 2007 (UTC) reply

The first part of your statement is not in conflict with what I wrote. There is no analogy to a normal use of speed given, it is speed. The couple of minutes you took to read my reply was fast– there is no need to find distance, though it can be found. That we set the amount of time before it shuts is irrelevant to the action/event. And the rate that a shutter can return is pertinent in high speed photography, modern cameras are faster. Cygnis insignis 17:07, 2 September 2007 (UTC) reply

← Manamarak 17:38, 1 December 2007 (GMT)

I agree, shutter rate would be a more accurate description, but the general usage refers to shutter speed, so we are stuck with it.

---(separate comment)
(This is my first post: All the formatting has not soaked in yet.)
Any physics book and many high school algebra books tell you that speed is distance divided by time. You cannot correctly say speed is any kind of time. You can say:

• (Shutter) speed is inversely proportional to (exposure) time.
  
• Shutter speed is the distance the shutter travels divided by exposure time.
  
• An exposure time of 1/125 seconds has or gives a relative shutter speed of 125. That is, it is perfectly correct to use the denominator of fractional exposure times when speaking about relative shutter speeds. It is tenuous and imprecise (but acceptable as a sort of slang) to call the denominator or reciprocal of a fractional exposure time the shutter speed because you usually don't know the distance the shutter traveled (and, thus, you haven't calculated the actual shutter speed by dividing distance by time).
  

Relative shutter speed, which is defined for any particular camera as the ratio of the shutter speed associated with (nominally) a one second exposure time to the shutter speed associated with any particular exposure time, is a useful and accurate quantity. Because the distance the shutter travels for both exposure times is the same, the relative shutter speed is always the ratio of an exposure time of one second to a particular exposure time (t_o/t), for instance, RSS = t_o/t = (1 sec)/(1/125 sec) = 125. This is the quantity that photographers often try to use (inaccurately) when they talk about an exposure time of 125 or a shutter speed of 1/125. (It's an accurate quantity.)

Many cameras simply inscribe or report relative shutter speeds (the denominators of their exposure speeds) for fractional exposure speeds instead of exposure speeds themselves. The common (midtone) exposure equation, A²/t = LS/K, can be simply written in terms of it: A² x (t_o/t) = L(t_o)S/K. It makes the exposure value easy to calculate: EV = log₂(A²) + log₂(t_o/t). (It's a useful quantity.)

Lens speed and film speed are separate topics, which can be related to shutter speed but which are not speeds by definition. They should be addressed elsewhere and not used to misdirect or squash a discussion of shutter speed.

(BTW, a speed is a specific instance of a rate in mathematical parlance.)

Generations of photographers have stumbled on the definition of shutter speed--the most fundamental of concepts. This is an encyclopedia and a place where it should be correct. You just can't go around saying confusing things in an encyclopedia.
Calculist ( talk) 16:27, 15 October 2008 (UTC) reply

The photography field uses lens speed, film speed, shutter speed, and such, all unlike the physics speed you're referring to. It's just a different use for the same word. Don't try to warp it to your preconceptions from a different field. Dicklyon ( talk) 20:36, 15 October 2008 (UTC) reply

That's not a very nice attitude--classic but not nice--not much in the spirit of the Wiki, either. Science and engineering should stay out of photography (after they make the cameras)? There is nothing that can be learned from them? Hurter and Driffield were the last good scientists? Right?

I'm very much into photographic science. Just saying we are not empowered to change or redefine the terminology; it's fine to explain it better, assuming the explanations are consistent with sources. Dicklyon ( talk) 00:09, 17 October 2008 (UTC) reply

Lens speed and film speed are indirect references to shutter speed, but shutter speed is a physical quantity. It deserves a better explanation than authors give it. The explanations here have been trying to fit a square peg into a round hole. It helps to be open to new insights and new ideas. It usually helps everyone.

Here you're redefining shutter speed. The speed at which parts of the shutter move is NOT what's called shutter speed. Dicklyon ( talk) 00:09, 17 October 2008 (UTC) reply

You haven't respectfully and intelligently countered any of my statements. You must have strong points to make. I have seen them on other articles.

-- Calculist ( talk) 21:46, 15 October 2008 (UTC) reply

Ancient peoples recognized the concept of speed well before even Aristotle wrote his Physics. It has become a convention that one runner, horse, worker, rock, or arrow moves at a greater speed than another if the first reaches his, her or its objective in less time that the other. When you travel to work, it doesn't matter how bad traffic was or where you stopped, everyone understands that you got here sooner today compared to yesterday when you tell them that you traveled faster or at a high speed today compared to yesterday. You can't change the convention associated with speed any more than you can change grammatical conventions that Wikipedia uses. It's also helpful for everyone's understanding of the relationship between exposure time and shutter speed to use the convention to explain that relationship. The questions that started this discussion are questions about the abuse of that convention.

In photography, speed is indeed associated with the concept of "less time", as opposed to rate of motion. That would be a good thing to say. Dicklyon ( talk) 00:09, 17 October 2008 (UTC) reply

It is certainly the case (and it should be noted in the article) that cameras do not have a piece of their mechanism that moves over a distance in a way that can be timed to calculate the shutter speed. (See The Manual of Photography for shutter mechanisms.) A camera is a mechanical system; there is movement; and picturing analogous movement helps photographers understand the relationship between shutter speed and exposure time. (Just like all the editors of this article are working to make the English statements clear, I am working to make the mathematical statements clear.)

I haven't encountered that notion of "movement" being relevant to speed in photography. Dicklyon ( talk) 00:09, 17 October 2008 (UTC) reply

Perhaps the article should be called Exposure Time and should ignore shutter speed except for a footnote. Exposure time is the fundamental quantity. Shutter speed is the derivative quantity. As far as I can tell Basic Photography - Materials and Processes does not mention shutter speed and The Manual of Photography cavalierly substitutes shutter speed for exposure time without any definition of shutter speed. Photographic literature does not address the definition, but universal convention can be applied to create an understandable and acceptable definition. It can help the reader with this fundamental concept. It is necessary for full understanding. As a product of consensus of the editors here, it is not one person's research. What say ye?

-- Calculist ( talk) 22:28, 16 October 2008 (UTC) reply

I'm sure there are plenty of great sources that call it "shutter speed". And some fewer that pair that with "exposure time". Surely you can find good definition and explanation in such a source. Dicklyon ( talk) 00:09, 17 October 2008 (UTC) reply

Though technically wrong, the use of “shutter speed” to mean “exposure time” is long established in photographic terminology, and as Dick mentioned, it is not the prerogative of Wikipedia editors to correct such wrongs, however annoying we may find them. I often use “exposure time”, as do the ANSI and ISO standards, but usually relate it to “shutter speed” on first use to make sure I don't lose some readers. I would have no problem with moving the title to Exposure time, but I'm not sure this would sit well with the majority of editors or readers. A more practical compromise might be to add a note that “exposure time” is the proper term.

The situation here is similar to changing the definition of Exposure value to make it technically correct; right or wrong, that definition is well established, and we simply cannot change it. JeffConrad ( talk) 01:37, 17 October 2008 (UTC) reply

"Shutter speed" is certainly a frequent-used synonym for "exposure time". It works fine as an imprecise stand-in. That should be said, but I contend that "shutter speed" has never been defined (as far as I can tell):

• It is never mentioned in the seminal articles of Jone and Condit.
• It is never mentioned in Nelson's article on safety factors.
• It is never mentioned in the "exposure" articles in Mees' "The Theory of the Photographic Process" (fourth edition 1977). (I can't say about the other articles.)
• It is never mentioned in Neblette's "The Manual of Photography" (sixth edition 1962).
• It is never mentioned in Stroebel and others' "Basic Photographic Materials and Processes".
• It is never mentioned in Ray's "Photographic Data".
• It is used as an equivalent to exposure time without a definition in Jacobson and others' "The Manual of Photography" (eighth edition 1997).
  

• It is used as a title in ANSI PH2.12-1957 but it refers to "shutter speed markings" for "effective time intervals" for fractional times.
• ANSI PH2.12-1961 uses "Shutter-Time Scale" as the title and continues to refer to "shutter speed markings" for "effective time intervals or time values" for fractional times. It does allow for markings of the form "1, 2, 5, ..., 500". It refers to the time variable T as "shutter time".
• ANSI PH3.49-1971 uses "Exposure-Time Scale" as the title and continues to refer to to "shutter speed markings" for "effective time intervals or time values" for fractional *times. It refers the time variable T as "effective exposure time". The APEX appendix refers to the time variable T as "effective shutter time".
• ISO 2720-1974 refers the time variable T as "effective exposure time (shutter speed)" and "effective exposure time scale markings" for fractional times.
• ANSI/ISO 2721-1982 (ANSI PH3.301-1990) simply refers to "exposure time with values according to ISO 2720".
  

• The earliest mention of "shutter speed" in an abstract of the Journal of the Optical Society occurs in a 1923 article by Castleman. The fourth mention of "shutter speed" in an abstract of JOSA is by Jones in 1923. JOSA is where Jone and Condit published their seminal articles. None of the abstracts suggest a definition for "shutter speed", and I'll have to go into the stacks after JOSA volumes to check the articles to be sure.
• The Journal of Imagining Science and Tech does not mention shutter speed in a camera context.
  

The point is: "shutter speed" is used, but it has never been defined. The mention of "shutter speed markings" simply says that it is a label. Thus, it is barely a term, and it is not a concept without a definition.

"Exposure time" is the primary concept. The lack of a definition limits under Wiki rule what can be said about shutter speed. (I'm out of time--more to come.)

(BTW, Mack and Martin in "The Photographic Process" (1939) p69-70 define the speed of a lens to be "inversely proportional to the time required for a certain exposure under identical eternal conditions." I don't have a copy of the whole book to check what they say about "shutter speed".) -- Calculist ( talk) 01:11, 27 October 2008 (UTC) reply

So, What do we know about shutter speed? We know that:

Shutter speed is a commonly used synonym for exposure time.

The term shutter speed originated at least as long ago as 1923, but the original definition is not known.

Primary research papers may mention shutter speed as a convenience, but it is only exposure time that is used for any analysis.

As a concept, shutter speed is problematic (confusing) because:

• A speed is well known (mathematically) to be inversely proportional to time, so shutter speed cannot be equal to time.
  
• The measurements of the actual shutter speeds of common (leaf and curtain) shutter mechanisms do not correlate with exposure times. (See Stroebel and others, BPM&P p37.)
  • The actual shutter speed of a leaf shutter is measurable as the displacement of the leading edge of the leaf as it moves in time from the center of the shutter to its open position. A leaf shutter has another displacement in time as the shutter closes for which another (perhaps equal) shutter speed can be measured. The exposure time is the sum of the relatively short opening and closing times plus a much longer time over which the shutter is held open to expose the photosensitive array. Opening and closing times are designed to be relatively short because the motion of the leaves exposes the center of the array for longer times than the edges of the array. (An average or overall shutter speed can be calculated for the shutter mechanism as the distance a leaf travels divided by the sum of the times mentioned. As leaf shutters were around in the late 1800s, this may be the origin of the term shutter speed.)
    
  • The actual shutter speed of a curtain shutter is measurable as the displacements of the leading edges of two curtains as they move across the shutter from one side to the other. These two measured speeds should be as similar as possible to create a opening between them that exposes all parts of the array equally. Only the shortest and longest exposure times are determined (limited) by the speed with which the curtains travel. The exposure time is determined by the difference in the starting times of the two curtains.
    

Therefore, shutter speed is not measured; exposure time is. The way that shutter speed is used is always in reference to exposure time and always in a way that agrees with the inverse proportional relationship between speed and time. This relationship is implicitly born out when standards and manufacturers use reciprocal exposure times for shutter speed markings.

The current article discusses exposure time calling it shutter speed. Because of the above listed problems with shutter speed, the article either should be recast in terms of exposure time with a caveat about shutter speed, or should include the recognizable problems with shutter speed as a concept. Recognizing the sequence of reciprocal exposure times (1, 2, 5, ..., 500) that everyone is so used to seeing on their cameras as a good measure of shutter speed--faster speeds refer to (do not equal) shorter exposure times (forget about what I said about relative shutter speed), the article would be stronger and less prone to confusion caused by a lack of a consistent definition for shutter speed.-- Calculist ( talk) 14:12, 27 October 2008 (UTC) reply

I expect you're right that the article can be strengthened by clarifying the origins and meanings of the terminology. But if you're proposing moving the article to exposure time, I think I don't agree. Shutter speed is the most commonly used term for the concept that the article is about. Dicklyon ( talk) 16:10, 27 October 2008 (UTC) reply

The latest change is an improvement, but it's still not quite right—the implication is that the setting (“shutter speed”) is something different from the phenomenon (“exposure time”), when in fact the two are synonymous, as is made obvious in the various ANSI and ISO standards for exposure meters. I think we need to say something like “... shutter speed refers to exposure time” or “... shutter speed is the common term for exposure time”. It's even somewhat of a stretch to say that this is “the length of time a shutter is open”; without qualification, this isn't true in the case of the traveling slit in focal-plane shutter or even in a leaf shutter (which is why the technical standards refer to “effective shutter time”). JeffConrad ( talk) 20:46, 28 October 2008 (UTC) reply

Jeff, please go ahead and fix it better; I realize I may have gone a bit off to the side on that edit. But also try to fina a source to support a change in defition that better includes the focal-plane version. Dicklyon ( talk) 22:46, 28 October 2008 (UTC) reply

I've tried to address the first issue, and provided a suitable reference (strictly, Ray states “The effective exposure duration (‘shutter speed’) ...”). Adequately describing the different issues with focal-plane and leaf shutters is a bit more involved (and seems to depend on Adams or Stroebel in addition to Ray), so I've ducked it for the moment. I moved the citation to indicate that it applies only to the clause that precedes it. Interestingly, I noticed that Adams as well as Ray uses scare quotes for shutter speed.

The two citations to the Manual of Photography are in slightly different format—I cited Ray, the author of the specific chapter, while the earlier reference cites the work as a whole. Dick, it looks like you added the first reference; did you have a specific page in mind? If it's the same chapter I cited, “ad hoc” seems a bit cruel—the earlier progression was consistent and logical, if not convenient. JeffConrad ( talk) 02:16, 29 October 2008 (UTC) reply

I added "effective", moved the ref back, and merged the two, since we're looking at adjacent pages or a two-page discussion. The ad hoc series 1, 1/2, 1/5, 1/10, 1/25, etc. is on 132; note the factors of 2 and 2.5, not even in a periodic pattern. I didn't mean the term ad hoc to be derogatory, just that it was what it was, not nicely related to stops or anything we're familiar with today, whhich is what Ray contrasted it with in modern shutters; find a better way to describe it? Dicklyon ( talk) 04:58, 29 October 2008 (UTC) reply

Good way to handle it; if someone has a problem with “effective shutter time”, we can add a note. In any event, I think adequate treatment is probably better handled in the Shutter article.

I didn't mean to suggest that “ad hoc” is derogatory, but it does have the implication of something temporary. Moreover, the note seemed to imply that the reference considered the earlier series “ad hoc”; I looked for something to that effect on p. 132, and found only the series that you listed. I don't think those who instituted that scale considered it temporary; they just didn't consider the convenience of reciprocal changes in exposure time and aperture. The 2 vs. 2.5 progression is probably nothing more than rounding as we see in the current progression. When APEX was proposed, the ASA committee made a big deal out of having the progression for all exposure parameters be integral multiples of ${\displaystyle {\sqrt {2}}}$ (${\displaystyle ^{3}{\sqrt {2}}}$ for speed); I assume that's still true for shutter and aperture controls, but the current ISO speed standards don't seem to be so fussy. It's not that big a deal, though it might be better just to list the earlier series than to pass judgment.

In any event, I think the introduction of the topic is now better than the vast majority of sources I examined. Sometimes what's common knowledge is surprisingly difficult to define. Potter Stewart would understand. JeffConrad ( talk) 05:58, 29 October 2008 (UTC) reply

The purist approach would be to move the article to Exposure time; use of that term in so much of the formal photographic literature would make for good justification. But if the page were so moved, the term used in the article would need to follow the page move, and that might be more likely to confuse than to educate—the opposite of the purpose of an encyclopedia. A more practical approach would be to indicate in the lead section that “shutter speed” is a misnomer and use the term in the rest of the article. For example, the first sentence isn't really correct as it stands; it could be changed to something like “In photography, shutter speed ^[1] refers to the length of time a shutter is open ...” I'm sure this wording could be improved, and other similar approaches are possible: the first mention of shutter speed could use scare quotes, as is done in the articles on Exposure value and APEX system.

In any event, though Calculist is technically correct, he would address a problem that essentially does not exist. Yes, “shutter speed” is a stupid term, but no worse than “fast lens”, “dragging the shutter”, and so on. I think a mention of the misnomer is indicated, as Imroy suggested two years ago, but a discussion of the problems with the concept would serve no useful purpose, and would probably violate NPOV. JeffConrad ( talk) 08:50, 28 October 2008 (UTC) reply

What about moving the second paragraph after the list of exposure times ('The term "speed" ...') into the first paragraph of the article? It is very general, and it really doesn't connect well with the specific speed increments. In that first paragraph, "duration of light reaching" sounds better as "duration of the light reaching". In the third paragraph, "...when exposed by the shutter." should include "and aperture" and perhaps scene luminance as initially posed contributors to exposure. In the next paragraph, I'm not sure that shutter speed is literally exposure time. Certainly, exposure time is literally (written down as) shutter speed. Perhaps shutter speed is more accurately exposure time. Would you accept "a commonly used synonym" in place of "the common term" in the opening sentence?

I notice that we mention both “shutter speed” and “exposure time” at least different places, and do so in slightly different ways each time; it would seem to me that we should relate the terms once and then stick with tone term or the other for the remainder of the article. The mention of faster “speed” being used to mean shorter exposure time and slower speed being used to mean longer exposure time should be included, context and use of the scare quotes should more than suffice to eliminate confusion.

I guess I don't have a problem with “synonym”; this usage appears in both Webster's Unabridged and Webster's 11th Collegiate dictionaries (though it's under “speed” rather than “shutter speed”). I would prefer “strictly” to “literally” or “more accurately”. But if we mention the equivalence at the beginning, I think we could stick with one term or the other. Yet another approach is to use exposure time followed by shutter speed in parentheses and scare quotes, e.g., say exposure time (“shutter speed”). JeffConrad ( talk) 05:28, 3 November 2008 (UTC) reply

I should probably add that, although I don't have a big problem with the proposed wording, I prefer the wording as it stands, or “commonly used term for”, as Dick phrased it. Something about “synonym” seems unnecessarily stiff; moreover, it fails to convey that, though “exposure time” the proper term, it sees little use in practical photography outside of manually timed exposures. JeffConrad ( talk) 07:27, 3 November 2008 (UTC) reply

The wording the term for sounds to me like twisted grammar. I have heard the term that and the synonym for but not the term for. -- Calculist ( talk) 18:21, 7 November 2008 (UTC) reply

What's the complete context of the term that? As to synonym, in addition to finding it a bit stiff, I also find it a bit strange to apply both misnomer and synonym to the same term. Why not go with Dick's wording? JeffConrad ( talk) 21:38, 7 November 2008 (UTC) reply

"The agreed standards for shutter speeds are" not the values in that following list. ANSI PH2.12-1957 "General-Purpose Photographic Exposure Meters (Photoelectric Type)" section 3.4,3 calls these items currently listed in the article "shutter speed markings". It says:

Shutter speed markings shall one or both series of effective time intervals of 8, 4, 2, 1, 1/2, 1/5, 1/10, 1/25, 1/50, 1/100, 1/200, 1/400, 1/800 seconds, or 8. 4, 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, and 1/1000 seconds, or both. While the second series of numerals is not exactly in power-of-two steps, it is intended that the time-interval calibrations on the meter scale shall be in exact power-of-two stops starting with the longest times. [I can't see that either series of time intervals is in exact power-of-two stops.] One or the other series of numbered markings, or both, should be shown. If intermediate divisions are used, consecutive divisions shall be in the ratio of approximately cube-root-of-two increments.

The successive standard ANSI PH2.12-1961 section 3.4.3 limits the markings to the latter (modern ...1/2, 1/4, 1/8, 1/15,...) set , but allows "The series 1, 2, 5, 10, 25, 50, 100, 200, 400, 800 may be used as an alternate." While this language is paradoxical, the successive standard ANSI PH3.49-1971 and its successor ISO 2720-1974 no longer mention and, thus, no longer allows the older alternative series. The standard for camera-held meters, ANSI/ISO 2721-1982 (ANSI PH3.301-1990), refers to ISO 2720-1974. I'd have to say that the current standards are pretty fussy. ANSI PH2.12-1957 predates APEX, too.

ANSI PH2.12-1957 also defines the "numbered relative aperture markings" as "the series: 2, 2.8, ...32." (It also states that "If intermediate other divisions are used, they shall be 1/3 f-stop increments.") This standard refers to ANSI Z38.4.7-1950 "American Standard Lens Aperture Markings." I am surprised with Ray's description of shutter speeds in the section "The shutter". It's as though he had not read the standards. (I'm curious how Neblette worded this in the sixth (1960) edition. He pretty much mimics the standards.)

Where's the discrepancy? Doesn't the list in the article agree with the modern standard you've just quoted? Dicklyon ( talk) 03:57, 3 November 2008 (UTC) reply

I had the same reaction as Dick. JeffConrad ( talk) 05:28, 3 November 2008 (UTC) reply

The standards consistently agree that the markings for shutter speeds are as listed. The standards are not specific as to the values that should be used. You have listed what most people believe are the common shutters speeds. I believe that manufacturers use cube root of two values to get consistent exposures for equivalent combinations of settings, but that's neither here nor there. There is nothing in the standards to say what shutter speeds the manufacturers should use. The values can not be verified. So, the wording should not suggest what the standards do not. It is, however, appropriate (verifiable) to say that the standard markings for shutter speeds are: -- Calculist ( talk) 18:21, 7 November 2008 (UTC) reply

The last sentence in the paragraph that follows the list of shutter speed markings, particularly the second clause is not supported and should be eliminated. The first clause is suspect, too: I expect that the exposure times and the shutter speed markings, especially in cameras made in the last half century, have values that are precisely powers-of-two divisions of 1/1000 of a second just like aperture numbers. Otherwise, you cannot create reliable zones with any combination of shutter speed and aperture number. If the manufacturers use precise exposure times, then the shutter speed markings are labels that represent the precise exposure times that only now in the information age are so familiar to so many: 32, 16, 8, 4, 2, 1, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, 1/256, 1/512, 1/1024, 1/2048, and 1/4096 seconds. There is nothing written to support this except for the proposition that various combinations of shutter speeds and aperture numbers give the same exposures, however, you can't say this unless shutter speeds and aperture numbers vary by the same factor (of two or the cube root of two).

I agree that the “last sentence” mentioned above is shaky. ASA PH2.12-1961 and ANSI PH3.49-1971 indicate that actual values are in power-of-two progression (notes to Table 2, in both cases). ISO 2720:1974 drops the note, but I assume the power-of-two progression still holds. JeffConrad ( talk) 05:28, 3 November 2008 (UTC) reply

Show me a reference from about the time of the 1957 or the 1061 standards (which mention this older series of exposure times) that states that "mechanical shutter mechanisms were rarely precise enough ...." Otherwise, this clause should be eliminated as unverifiable. It's a fabrication that doesn't belong here. Why even mention the series for older cameras--actually the series from older standards? Also, don't you think that the audience should be treated to an explanation for why 1/8 and 1/15 as well as 1/60 and 1/125 are not covered by your statement that "[e]ach standard increment either doubles the amount ..."? (BTW, this series is not a series of increments. You should be saying "each shutter speed..." or "each value in this series...". This is a nearly geometric series that has multiples of a starting value.) -- Calculist ( talk) 18:21, 7 November 2008 (UTC) reply

The issue about references for the types of shutters and their effective speeds could be resolved by using Stroebel (p40) to cover leaf shutters and Ray in TMOP (p100 in the eighth edition). Stroebel has a nice diagram that shows the position as a function of time for the leaf shutter. Ray just above the figure labeled "The focal-plane shutter" describes the "effective exposure time to any portion of the film frame to be given by the slit width divided by the slit velocity [the shutter speed]." I think that the comments that I made above about what we know about shutter speeds could be adapted (with these formal references) and be useful description of this sub-topic in the article. I think that this contradiction is something that should be recognized. (I also noticed in reading that Stroebel mentions exposure corrections for leaf shutter coverage of various apertures that have not been covered in the article.)-- Calculist ( talk) 01:47, 3 November 2008 (UTC) reply

There's no reason anyone should confuse slit velocity with shutter speed; it's not clear why you've written it that way. Dicklyon ( talk) 03:51, 3 November 2008 (UTC) reply

Again, I agree with Dick. A person who knows enough about photography to know about slit widths is certain to know what is meant by “shutter speed”.

Not the point. The slit velocity is the common velocity of the curtains--the shutter. Recognizing this, you can say that the shutter speed (aka exposure time) is not the physical speed of the shutter. Secondly, is the article written for the person who knows enough...? I don't believe so. The article should be more informative. -- Calculist ( talk) 18:21, 7 November 2008 (UTC) reply

I don't have a problem with putting shutter speed in scare quotes in the first sentence (as so many other works do) and even adding a footnote indicating that “shutter speed” isn't the physical speed of the shutter (as few works seem to do). If we add a note, we should be careful not to imply that a focal-plane shutter is the only kind. I agree that the article should be informative. As to the audience: conversely, my point was that a person new to whom “shutter speed” is unfamiliar isn't likely to be worrying about slit velocity. Perhaps I am mistaken. JeffConrad ( talk) 21:38, 7 November 2008 (UTC) reply

After further consideration, I think mention of effective is going to invite the question, “Just what does ‘effective’ mean?” This may not be easy to answer without some additional material on shutters, especially leaf shutters. I'm not clear on your reference to Stroebel; I have View Camera Technique, 3rd ed., which covers shutters beginning on p. 88. If the material is essentially the same, that's a good start; Ray's treatment should also be acceptable. I'm still not sure I know how to reduce that to a sentence of two even with the reference. Perhaps the topic just needs expanded treatment in this article—maybe a separate section. JeffConrad ( talk) 05:28, 3 November 2008 (UTC) reply

Stroebel and others, Basic Photographic Materials and Processes (1990). -- Calculist ( talk) 18:21, 7 November 2008 (UTC) reply

I disagree with the section Bulb ("B (bulb) (1 minute to several hours): Used with a mechanically fixed camera in astrophotography and for certain special effects."). There is no 1 minute lower time limit for the Bulb shutter speed. I guess, that the lower limit is actually the X-sync speed (for DSLR-s usually 1/250 s). And mechanically fixing the camera is also not a must for using the Bulb shutter speed. 194.126.101.134 ( talk) 10:05, 18 February 2016 (UTC) reply

There are too many pictures, it is crowded, I think some can go. Any suggestions on which ones? Shoeshirt 23:39, 7 June 2007 (UTC) reply

I voted with my delete key. Dicklyon 00:45, 8 June 2007 (UTC) reply

Ahh, it looks much less cluttered now. Shoeshirt 02:08, 8 June 2007 (UTC) reply

There's too many light streak photos. Quality over quantity. Limiting it to just 'Light streaks outside Waterloo Rail Station in London' would be more suitable. -- Wisie ( talk) 05:48, 23 October 2011 (UTC) reply

Some of it's OK, but the last edit seemed like it messed up the lead paragraph pretty good, so I reverted it. I'll try to work on it a bit later. Dicklyon 01:33, 3 September 2007 (UTC) reply

1/8000 s is not an extraordinary claim. You should be actively improving the page, not camping out and making unilateral decisions about the content. Cygnis insignis 07:47, 3 September 2007 (UTC) reply

No, 1/8000 is not at all unusual, but it's not from the list given in the referenced source; and it already says that the series is commonly extended on both ends. If you'd like to change to a different source to support your edit, that would be fine. Dicklyon 16:24, 3 September 2007 (UTC) reply

I apologise to you, as you regarded my insinuation as uncivil. I was annoyed, it was an intentional comment. Please, don't alter people's posts, it will get up their nose and is an example of what I implied. Moving along ... My last EC was confession that it might have muddled things. However, I think that you, and I, have improved the page - if only a little. I notice that In photography, shutter speed ... is at the start again. If there is another kind, can we disambiguate that? I think that this articles difficulties may arise in attempting to make in one in a series of– . I tried to make reference to other concepts from the POV of shutter speed. The article now explains shutter speed in a clearer way, but can we add something about the limitations of speed. By the way, are you sure that it is internationally accepted. Cygnis insignis 21:20, 3 September 2007 (UTC) reply

I figured you'd be happier to have your intentional insinuations removed than see them lead to a less civil discussion, but I take your point. Anyway, yes, camera standards are very international, since the manufacturers all target global markets, but there will still be come variations, too; I believe these numbers can be traced to an ISO standard of around 1960 (the APEX system), though they were in use much earlier, too. It is conventional in wikipedia articles to introduce the topic with the field that it is part of, hence the "In photography..." even though there may not be other interpretations. Dicklyon 23:15, 3 September 2007 (UTC) reply

The only convention, I am aware of, is having the title as close to the beginning as possible. It gets back to my 'article series' statement; it gives the reader an explanation of shutter speed, and restricts us to explaining only that. The tricky bit is explaining it within the context of photography, but also the mechanics of it. 5 'W's, to be trite.

• "[The] Shutter speed [of a camera; in photograpy; is when] ..." - Maybe I'm being petty.

Is there another kind of shutter speed? –it should be mentioned. I thought the use of camera, in the first line, helped place the concept in context. Photography does that as well. Cygnis insignis 00:08, 4 September 2007 (UTC) reply

I've rewritten this accordingly to emphasize the actual duration x intensity = exposure formula. (Why isn't this even mentioned on exposure?) When people talk about shutter speed, they are not actually discussing the speed of the shutter opening and closing (which is designed to be as close to instanteous as possible) they are discussing the actual exposure time. We use the length of time (duration) and the intensity (aperture) to control the exposure itself, and the sensitivity of the film or sensor then reacts to that exposure within its range. Keeping the concept clear is essential. Girolamo Savonarola 06:19, 4 September 2007 (UTC) reply

I took another whack at it. I think the concept of total exposure needs to be in the opening paragraph, since controlling that is one of the main things the shutter speed is about. And in the next paragraph, the duration x intensity thing really needs to menion the scene luminance to be complete; so I added a bit about that, since aperture itself does not determine intensity. The Exposure (photography) article does say that total exposure is measured in lux seconds, which is intensity (focal plane illuminance) times duration. It also points out that the EV (shutter speed and aperture combination in stops) needs to be combined with scene luminance to figure the total exposure. It might be worth trying to further clarify all this. Dicklyon 06:40, 4 September 2007 (UTC) reply

I'm not certain I totally agree about the scene luminance - that will affect the image rendering, based on the sensor/film response, but it has no bearing on the physics of the exposure. The equation defines exposure as any shot, regardless of its artistic merit or ability to fall within exposure latitude. In other words, any shot will have an exposure equal to intensity times duration. Whether or not it renders (exposes) decently is a function of the sensor/film, which is a completely separate consideration. Girolamo Savonarola 07:10, 4 September 2007 (UTC) reply

It agree it's not about the rendering, and is independent of the ISO speed, but if the scene is dark, the total exposure will be zero no matter what the exposure time and aperture. You need to get an intensity into the formula to get to the lux-seconds of exposure. Dicklyon 15:06, 4 September 2007 (UTC) reply

You're missing my point - all photos are technically exposures, regardless. It may be zero lux-s, but it's still an exposure. Any case, is it even true? There's not much true black that won't expose something given a long enough exposure time. Girolamo Savonarola 15:35, 4 September 2007 (UTC) reply

Yes, and the "EV" (exposure value) is a measure of what you're talking about. But that's not the "total exposure", which as you point out is intensity (focal plane illuminance) times duration. You can't substitute one for the other. Dicklyon 16:15, 4 September 2007 (UTC) reply

A total exposure which is zero is still an exposure. It's run through the camera and was exposed to the sensor. My point is that you can consider the exposure a measurement of everything which will hit the sensor, measured just before it hits the sensor. Girolamo Savonarola 16:40, 4 September 2007 (UTC) reply

But you need to be clear about what measurement you're referring to. An exposure of 10 EV corresponds to f/32 for 1 second or f/1 for 1/1000 second, but doesn't say anything about how much light you're measuring. A measurement of 1 Lux-second, on the other hand, is an amount of light, proportional roughly to so many photons per pixel or whatever. The latter is known as total exposure, and requires an intensity input such as scene luminance. Dicklyon 16:52, 4 September 2007 (UTC) reply

Perhaps I'm not being clear- the aperture controls the intensity, but the intensity itself is an amount of light (lux or ft-cd). Intensity times time equals exposure. Girolamo Savonarola 17:10, 4 September 2007 (UTC) reply

Yes, it controls the intensity by how much of the light from the scene it admits. I get that. But it does not determine the intensity; you still need the scene luminance if you want to connect to the total exposure in lux-seconds. Dicklyon 20:49, 4 September 2007 (UTC) reply

While I'm thinking about all this, is there really a good reason why this article should be separate from shutter (photography)? It just seems kind of absurd that the two are split from each other. Girolamo Savonarola 17:12, 4 September 2007 (UTC) reply

"Absurd" is a bit of a stretch. The contents hardly overlap. One is about the mechanisms, the other about how the time is uses as a parameter. Having leaf shutter as a separate article is a bit silly, though. The division of content between aperture, f-number, diaphragm (optics) is perhaps a bit much, too, but not as bad as "absurd." Dicklyon 20:47, 4 September 2007 (UTC) reply

Much as we're debating definitions, don't take my diction in that comment too literally! :) I'm just pointing out that it probably makes more sense (in the view of a long-term goal of eventual FA) to combine the shutter theory with the physical shutter. Girolamo Savonarola 21:22, 4 September 2007 (UTC) reply

Feel free to make a merge proposal. I might oppose it, but I'll think about it. Dicklyon 21:32, 4 September 2007 (UTC) reply

I propose to add links to relevant external sites where shutter speed is explained. Examples are http://www.illustratedphotography.com/photography-tips/basic/shutter-speed and http://www.ephotozine.com/article/Camera-Shutter-Speeds-explained

I furter propose a section discussing the creative usage of shutter speed in photography, specifically discussing the visual effects which can be obtained through manipulating shutter speed. ← Manamarak 17:38, 1 December 2007 (GMT)

Be sure to read up on WP:EL, and see if you can include content in the article, with those sites as sources, rather than using external links per se. Good idea on the new section. Dicklyon 18:05, 1 December 2007 (UTC) reply

Thanks Dicklyon. I have added the above section, but I suspect I may have made a bit of a hash of the citation, if anybody can offer any suggestions, I would much appreciate it.

I will add another section relating to the difference between motion blur and camera shake when utilising slow shutter speeds unless there are any objections. Manamarak 21:35, 1 January 2007 GMT

There seem to be several problems with this section:

1. The symbol E surely refers to “exposure time” rather than “exposure”.
2. The formulas are the reciprocal of the formula in Rotary disc shutter (i.e., the first formula gives the reciprocal of exposure time); either the symbol definitions or the formulas should be revised.
3. The stated exposure times for shutter angles of 165° and 180° appear to be given in reverse order, and the value for 165° does not match that given by the first formula even if the formula is corrected.

JeffConrad ( talk) 00:51, 19 October 2008 (UTC) reply

The formula seems incorrect.. I think it should be:

${\displaystyle S={\frac {E*360^{\circ }}{F}}}$

WYarde ( talk) 09:53, 18 May 2009 (UTC) reply

As Jeff mentioned, the problem is that the formula is for shutter speed (reciprocal seconds), not exposure time; I clarified. Dicklyon ( talk) 14:43, 18 May 2009 (UTC) reply

Isn't this definition of shutter speed at odds with the one in the lead paragraph (shutter speed = exposure time)? Would it not be better to invert the formula and use the common definition? There's also the matter of the result for a 165° shutter angle; if it gives an exposure time of “about” 1/50 s, then so does a 180° shutter angle. JeffConrad ( talk) 07:33, 19 May 2009 (UTC) reply

Guys, someone should change the format of the "Creative utility in photography" as that huge white space in the middle of the page is quite annoying! Ty! — Preceding unsigned comment added by 194.81.223.66 ( talk) 08:27, 9 August 2013 (UTC) reply

This is a good article as the subject discussed and photos shown directly relate to the topic - which is shutter speed. Johnscotaus ( talk) 06:11, 28 November 2015 (UTC) reply