Shutter Efficiency w/ Leaf Shutters & Higher Speeds...

[Saganich]

I have noticed exposures which were greater then anticipated when shooting 1/500@f16. Never thought much of it until now.

[RalphLambrecht]

I have noticed exposures which were greater then anticipated when shooting 1/500@f16. Never thought much of it until now.

This combination is a candidate for slight overexposure, but I would be surprised if one finds it to be obvious with B&W negative films.

[holmburgers]

ic-racer, thank you for the clarification. I didn't mean to snap.

and John Koehrer, I apologize if I used confusing wordage. By "small aperture" I'm referring to the actual aperture size or iris diamater; that is, f/16 and up. Large aperture meaning f/5.6 (in the case of my lens).

[kristopher_lawrence]

you main problem will be the shutter calibration, especially at high speed. 500th of seconds is rarely attained in reality for instance on a leaf shutter.

Same with leica: the 1000th is rather a 750th in reality.

This never been a problem for me in real world situation even when shooting slides.

Best,

K

[lxdude]

Here's a question-leaf shutters have a "twisted star shape" when less than fully open. At higher speeds and small apertures is there any noticeable effect on bokeh, maybe in say, out of focus highlights?

[Ian Grant]

Here's a question-leaf shutters have a "twisted star shape" when less than fully open. At higher speeds and small apertures is there any noticeable effect on bokeh, maybe in say, out of focus highlights?

How can there be, the restricted aperture negates any effects of the shutter, other way around, fast speed & wider open then just a tad more DOF, less that sick US word

Ian

[Q.G.]

Correct, who said something different?

As the shutter opens, a small aperture is quickly revealed, while a larger aperture needs to wait until the shutter has fully opened. This can lead to underexposure with large apertures and fast shutter speeds, because the shutter delay becomes a significant portion of the the entire exposure time.

It never leads to underexposure. Always to overexposure.

I know, i know: you were explaining things.
But only mentioning underexposure was enough for the OP to come back with "[...] but [...] at small apertures and high speeds you actually overexpose."
I confirmed that.

[RalphLambrecht]

It never leads to underexposure. Always to overexposure...

Incorrect!

I repeat your quote of my statement:

This can lead to underexposure with large apertures and fast shutter speeds, because the shutter delay becomes a significant portion of the the entire exposure time.

I stand by that statement, because during the shutter's operation, a small aperture is fully revealed for most of the time, where a large aperture is only fully revealed for a small fraction of that time.

[Q.G.]

Incorrect!

I repeat your quote of my statement:

This can lead to underexposure with large apertures and fast shutter speeds, because the shutter delay becomes a significant portion of the the entire exposure time.

I stand by that statement, because during the shutter's operation, a small aperture is fully revealed for most of the time, where a large aperture is only fully revealed for a small fraction of that time.

Yes.

And because people building shutters aren't stupid, they allow for that. The shutterspeed isn't measured form the time the shutter is fully open until it is not.
They can't allow for small apertures (they could, but neither you nor i would want to pay for such a shutter), and thats why - like i said - you always (!) get overexposure, never underexposure.
So even in textbooks explanations of why you get overexposure, that is correct.

[2F/2F]

ic-racer, thank you for the clarification. I didn't mean to snap.

and John Koehrer, I apologize if I used confusing wordage. By "small aperture" I'm referring to the actual aperture size or iris diamater; that is, f/16 and up. Large aperture meaning f/5.6 (in the case of my lens).

Aperture is the size of the opening in the diaphragm. F/stop is the number assigned to it. Smaller apertures = greater f numbers. "Nobody" ever casually uses the actual size of the opening in conversation, hence the confusion comes from the incorrect use of the word aperture, which is rarely going to be used in a casual conversation about photography. The word aperture is, often and everywhere, erroneously used to mean diaphragm (e.g. "aperture blades"), and to mean f stop (e.g. "stop down to a higher aperture").

My solution: I don't use the word aperture unless I am talking about the actual physical size of the opening in the diaphragm. Any time I am talking f numbers, I use the term f stops. People often say, "I know all my apertures and shutter speeds", and I correct them to saying, "I know all my f stops and shutter speeds". I am now also making a concerted effort to avoid the terms "stop down" and "stop up" when speaking with students. I will instead say "close down" or "open up".