Are the higher shutter speeds on large format lenses always off?

[cowanw]

Let me restate what I was getting at. For whatever maximum aperture you are using the shutter must pass though Aperture openings equal to smaller aperture fstops on the way to your chosen fstop. For example If you choose F 8 and as the shutter opens it passes by the diameter of F 64, 32, 16, 11.
You seem to be saying that when the shutter size is at and passing by these smaller diameter sizes the light (exposure) is concentrated in the center of the film or, alternately, optically vignetted on the outer edges of the film.
This cannot be true. If anything, by avoiding vignetting light distribution (coverage) across the breadth of the film is better at smaller fstops (I am thinking that shutter speed is not relevant to this particular discussion.) (Depth of field is also a different and maybe interesting idea. But we are speaking of exposure relative to size of aperture)

[Bernice Loui]

Easy, the film cinema folks do this all the time.

Apply enough Neutral Density filter to reduce the amount of light to film for a given shutter speed, DONE.


Bernice

This totally depends on your style of photography though. Some people shoot for bokeh. Ever try to shoot a f/2.5 lens wide open with 400 speed film? Suddenly even the 1/1000 shutter speed on your focal plane shutter camera won't be fast enough.

[Bruce Watson]

Is it common for the higher speeds to be slow by 1/2- 1 stop?

Yes. But it doesn't matter that much since you typically can't use those shutter speeds much anyway. In the decade I kept track of such things I only used a 1/125 speed once or twice. Nothing faster.

I found with 5x4 that I typically used apertures around f/16 at the widest. There's little reason to shoot wide open because of lens aberations. Most of these older lenses really want to be stopped down a couple of stops to control aberations and sharpen up. This in turn requires more time. Shutter speeds 1/8 or less are common. And this is with high speed films like TMY-2.

[cuypers1807]

I use the fastest shutter speeds quite often in studio portraiture using strobes since leaf shutters sync at all speeds. If the shutter doesn't quite make it to 1/125, it doesn't matter because the strobes are controlling the exposure.

[Bob Salomon]

I use the fastest shutter speeds quite often in studio portraiture using strobes since leaf shutters sync at all speeds. If the shutter doesn't quite make it to 1/125, it doesn't matter because the strobes are controlling the exposure.

But the shutter speed controls the ambient light. So, if you are using the fastest speeds you get dark backgrounds.

[cuypers1807]

But the shutter speed controls the ambient light. So, if you are using the fastest speeds you get dark backgrounds.

True, but I don't really want ambient light messing with my exposure if I am using strobes. I light my background if I don't want it dark.

[cablerelease]

Someone mentioned an app to check speeds. Which app is this? Is it accurate? Or would it be better to get a cheap dedicated tester? I understand it might be hard to get accurate readings on high speeds without very expensive equipment but, just to know if the speeds under 1/60th are close would be helpful.

[Jim Noel]

I have four lenses that I have tested with a shutter speed tester. Most of the shutter speeds are as they should be apart from the 1/250 and Higher speeds. Is it common for the higher speeds to be slow by 1/2- 1 stop?

Yes. My repairman for many years asked me which 3or 4 speeds I wanted accurate. He usuallywas abe to make them so. He always also reminded me that speeds faster tan 1/100 sec were controlled by an addtional spring and were highly unreliable. For those speeds I used the focal plane shutter on the Speed.

[Bob Salomon]

True, but I don't really want ambient light messing with my exposure if I am using strobes. I light my background if I don't want it dark.

But others may do portraiture within the subjects environment and want to emphasize or de emphasize the setting. That’s where shutter speeds come in.

[Jody_S]

For whatever maximum aperture you are using the shutter must pass though Aperture openings equal to smaller aperture fstops on the way to your chosen fstop. For example If you choose F 8 and as the shutter opens it passes by the diameter of F 64, 32, 16, 11.
You seem to be saying that when the shutter size is at and passing by these smaller diameter sizes the light (exposure) is concentrated in the center of the film or, alternately, optically vignetted on the outer edges of the film.
This cannot be true.

There are 2 issues that I raised in my post. 1 is the 'true' shutter speed. I said you need to measure the total volume of light passing through the shutter and divide by the opening to get a true shutter speed, since different parts of the opening receive wildly divergent opening times at high shutter speeds. You cannot measure this with a $15 shutter speed tester, since that will only give you the center of the shutter which is open the longest. Hence the common idea that leaf shutter high speeds are consistently slow. If you measure at the edge in the right spot, you will find they are consistently fast. I do not know of any easy way to do the required calculation to get a 'true' shutter speed without doing integration, either with an engineering software or an integrating oscilloscope. I do own such an animal, but it's a 1980s model and I can't find a user manual that would get me started, nor do I have any particular interest in proving my case.

If anyone is having trouble following this, imagine a garden hose. You measure the volume of water that passes through the garden hose and find it allows, say, 60 gallons per minute. Now you want to connect this to a timed valve for a fountain, and you need to know how long that valve stays open. So you run the valve through 1 cycle, and collect all of the water that passes through your garden hose. You measure 1 gallon. Now you want to know how long the valve was open: you divide that 1 gallon by the 60 gallons per minute at full open, and you calculate that your valve was open 1/60 minutes, or 1 second. It doesn't matter if the valve wasn't fully open for that 1 second, or if a portion of the area of the valve was open for 3 seconds; what you have measured is the effective, or practical, open time for that mechanical valve, without worrying about the underlying physics.


The 2nd issue is what effect these wildly divergent shutter speeds have on the image. I suggested that they may act as a reverse center filter, and you quite correctly point out that this is highly unlikely with a modern lens and center-mounted shutter. I gave the real-world example of an antique Petzval with a rear-mounted Shanel shutter to show that in some circumstances this might be so. But the question of what effect this variable shutter speed has on the image with a modern lens in a shutter at max speed and opening is beyond me (where's Nodda Duma when we need him?), I simply know how to calculate the average shutter speed for the entire area. Which, as I said, might be a lot closer to nominal speeds than most people think, since I don't think Copal was in the business of marketing false shutter speeds.