Exposure compensation for small apertures

[Drew Wiley]

It's not just the amount a shutter might be predictably off at the highest speeds, but unpredictably off. There is likely to be more variance of error than at other speeds. Every lens needs to be individually checked in this respect with a good shutter speed tester. And then there the added variable of this itself shifting once one moves away from common central aperture settings to especially wide or narrow ones. So yes, I check every single lens in advance, and detect where all the idiosyncrasies lie; but so far, NONE of that has affected my own lens usage because I don't work at the extremes of any of it. If I anticipate the need for high shutter speeds or wide f-stops, I resort to MF gear instead.

[Michael R]

Lucky for me I can’t remember ever using a shutter speed faster than 1/30s and anything shorter than seconds is very rare.

It's not just the amount a shutter might be predictably off at the highest speeds, but unpredictably off. There is likely to be more variance of error than at other speeds. Every lens needs to be individually checked in this respect with a good shutter speed tester. And then there the added variable of this itself shifting once one moves away from common central aperture settings to especially wide or narrow ones. So yes, I check every single lens in advance, and detect where all the idiosyncrasies lie; but so far, NONE of that has affected my own lens usage because I don't work at the extremes of any of it. If I anticipate the need for high shutter speeds or wide f-stops, I resort to MF gear instead.

[Michael R]

adding this to my list or reasons to like my speed graphic.

Honestly it’s one of those things nobody (besides Drew) would ever notice if you didn’t tell them about it. At anything slower than 1/500s it is easily lost in the rest of the slop on the photographic process.

[Bernice Loui]

Similar has been discussed in LFF past.
https://www.largeformatphotography.i...Picture-BEAUTY


In real world conditions, small apertures (ala f16 and smaller) combined with fast shutter speeds (1/500 or even 1/125 second) would be extremely rare film exposure conditions. While this is extremely common with digital and roll film, that ideology does not apply much to this LF view camera sheet film stuff.

Add to this, majority of view camera lenses never approach a 1/500 sec setting, even 1/125 second is uber fast for LF view camera stuff. Scaled "sunny f16" produce about f22 at 1/60 second with ISO 100 film speed. Given most LF subjects are not about "stopping" action, there is not a lot of need for shutter speeds above 1/60 second. Turns out, the slower shutter speeds of 1 second or greater is often more useful then shutter speeds above 1/60 second.


Essentially, this compensating for small apertures (ala f22 and all that) at high shutter speeds (1/500 sec) is much a "red herring"... move along,

Bernice

[BrianShaw]

Honestly it’s one of those things nobody (besides Drew) would ever notice if you didn’t tell them about it. At anything slower than 1/500s it is easily lost in the rest of the slop on the photographic process.

Ain't that the truth!

But in terms of terminology, I've never heard the term "shutter inefficiency" and always heard it as "shutter efficiency". Not picking on you, Michael (and not really interested in being pedantic, although that's exactly what I'm doing, it seems)... just trying to make sure that anyone trying to research it in the future has the best start.

https://www.google.com/search?rlz=1C...&bih=897&dpr=1

[xkaes]

To have this conversation, we have to all be on the same page -- which is difficult enough when including people who haven't read the book. I have the fifth edition where this is covered on page 67 & 68 -- without any table. He basically says to run some tests to see how much a difference this can make. I have never gone to the trouble of doing that since I can't remember the last time I used a shutter speed over 1/60.

[Michael R]

I think you’re right. It’s likely shutter efficiency (it’s been a while since I looked at the book). Actually if I remember correctly it’s mentioned in Adams’s The Camera too. Or maybe I’m thinking of Richard Henry. Anyway.

Ain't that the truth!

But in terms of terminology, I've never heard the term "shutter inefficiency" and always heard it as "shutter efficiency". Not picking on you, Michael (and not really interested in being pedantic, although that's exactly what I'm doing, it seems)... just trying to make sure that anyone trying to research it in the future has the best start.

https://www.google.com/search?rlz=1C...&bih=897&dpr=1

[Kiwi7475]

Just curious even if it’s clear that this doesn’t happen commonly in practice…. since the shutter is usually (for modern lenses on copal shutters at least) somewhere in the middle of the varios glass elements, and the light should be somewhat already collimated at that point, does that mean that the effect would show up more like an additional radial vignetting (like an additional vignetting to what already takes place when shooting wide open with fast lenses)?

[Dan Fromm]

Just curious even if it’s clear that this doesn’t happen commonly in practice…. since the shutter is usually (for modern lenses on copal shutters at least) somewhere in the middle of the varios glass elements, and the light should be somewhat already collimated at that point, does that mean that the effect would show up more like an additional radial vignetting (like an additional vignetting to what already takes place when shooting wide open with fast lenses)?

No. If you're thinking of mechanical vignetting, it is usually caused by the lens' rear barrel. Stopping down diminishes it. To see the effect, take a lens in shutter, open the shutter, open the diaphragm as wide as it will go, hold the lens at arms length and rotate it slowly (around a line in the diaphragm's plane, not around the lens' axis) and watch the end of the rear barrel begin to occlude the exit pupil. Stop the lens down and repeat the exercise. And then you'll understand why manufacturers of center filters advise stopping the lens down when using a CF. The CF can't do anything about mechanical vignetting, which dominates at large apertures.

[Kiwi7475]

No. If you're thinking of mechanical vignetting, it is usually caused by the lens' rear barrel. Stopping down diminishes it. To see the effect, take a lens in shutter, open the shutter, open the diaphragm as wide as it will go, hold the lens at arms length and rotate it slowly (around a line in the diaphragm's plane, not around the lens' axis) and watch the end of the rear barrel begin to occlude the exit pupil. Stop the lens down and repeat the exercise. And then you'll understand why manufacturers of center filters advise stopping the lens down when using a CF. The CF can't do anything about mechanical vignetting, which dominates at large apertures.

Right, right, Dan, I’m not saying the mechanism is the same, I’m asking whether the shutter opening slowly relative to the overall shutter speed (eg if it takes 1/1000 to open and 1/1000 to close and you selected a 1/500 shutter speed, such that the aperture has just enough to open to open and close, rather than offering a large fraction of exposure time being fully open) isn’t but in fact another mechanical vignetting effect — different from the one you mention (now induced by the shutter creating the vignetting) but that in fact compounds with it when you shoot wide open at extreme shutter speeds.