Testing leaf shutter consistency across speeds

I got out my old book from the jr high, from when the teachers were lecturing and I was "following along in my textbook". Of course my photography books were inside my textbook, so they wouldn't know. Here it is. the Haynes Shutter checker. Never saw one, but I bet it's dead-perfect, if you don't mind burning through some film to use it.

F4U said:

I recall in The Amateur Photographers Handbook by Aaron Sussman was depicted a Haynes Shutter Checker, I believe it was called. It was supposedly a phonograph disc that is set in motion and shot on film. I would think the object was to measure the angle of the motion-blurred image and calculate the shutter speed. Of course, those books date back to heaven-knows-when, most likely to be run on the 78rpm record players of the day, which were likely not highly accurate. Today there are strobes and DC motors allowing you to get turntable speed dead-on the money. If you don't mind burning up a few rolls of film, I bet it is still and excellent way to check shutter speeds. But now you can get cheap USB testers off ebay, which work very well on speeds below 1/50, but not so well on faster speeds of leaf shutters. So you'd use the USB tester for slow, and switch over to the Haynes on the faster ones, using up less film. Of course where are you going to find an old Haynes checker?

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I can make a spinning disk fast enough and accurate enough using stepping motor even for 1/500. For leaf shutter it would be OK. For focal plane shutter there is a problem that the rolling shutter effect would be different depending on where you capture the line.

I relly cn't see a way to do his accurately using this method.Lens performance won't be "out" by the same degree across all shutter settings. I wouldn't expect a straight line result. There is also a risk of the experimental method impacting the results themselves. Blades may loosen up with use which could impact the results quite markedly.

Have you noticed any impact on your results with lenses? Is there a fault to analyse? If that be the case, then surely it iss either identifiable as regards to the specific configuration. If not, then wwhy not simply work along with your camera?

I'd also want to thro a control in theree - perhaps another camera which has been calibrated?

runswithsizzers said:

As others have suggested, any testing procedure must evaluate not only accuracy, but also precision. Any comparrison of 1/125th second to 1/250th second is meaningless until you know how much variaion there is at 1/125th second. If 10 exposures at 1/125th second vary by +/- one f-stop, then sometimes 1/125th is 1/250th and sometimes 1/125th is 1/60th.

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While almost anal-retentive testing can yield more insight into absolute accuracy and precision of measurement, and high sample counts can find reliability, my own method is more pragmatic...

1. find a combination of [shutter speed + aperture] which, in constant lighting, would permit you to shoot the full range of shutter speeds under question
2. analyze the developed film to look for a consistent density across the entire series of exposures

...and this will give security that your camera lens-shutter is consistently exposing across the combinations. Isn't that all we want with our stuff?...consistency. Our apertures can be off, just as shutter speeds can be off, and one can counteract the other in a good way, or reinforce the errors to an even greater magnitude, and we need really to know which of the two we have to deal with.

I’ve finally started playing around with this in my studio. More to come once I develop the film and make the contact prints.

If you’ve got a smart phone, or a digital camera, that can shoot video at 60fps or more, you can simply film the shutter firing - and shoot a given shutter speed as often as you like. Then play it back in very slow motion or better frame by frame, and observe how many frames duration the shutter is open for, for a given shutter speed. Cameras that record time code can make this really easy to count.

Simple math. If a shutter is open for 15 frames on a 60fps frame rate, that’s 1/4 second. 8 frames would be 1/8. 4 frames would be close to 1/15th.

Obviously there are limitations in terms of faster shutter speeds unless you have a digital camera that can record at a frame rate faster than 60fps. Either way if your slower shutter speeds are inaccurate, your faster ones should probably be too and visa versa. And for all its basicness of approach and limitations, this is quite accurate. Frame rates are very temporally consistent relative to analog camera shutters.

My first approach would be along the lines of Koraks first post - digital audio waveform recording. Easy and highly accurate. But if you’re more a visual person maybe just using a basic digital camera to record the shutter action is easier.

I don’t think shooting a couple of rolls of film is as accurate. You’re not actually examining the shutter action itself, but an outcome. What if the aperture stops are not exactly double or half the adjacent stop? What if there’s fluctuation in the light levels. And you waste film.

The film is drying. Two lenses were used. It’s already obvious that 1/500 (the bottom frame) is a bit slow (darker), the next one is 1/250s, etc. More will be clear when I make the contact sheets.
I should say that the last time I shot slide film, I didn’t notice any discrepancy, so I concluded that both lenses’ shutters are okay-ish.

miha said:

The film is drying. Two lenses were used. It’s already obvious that 1/500 (the bottom frame) is a bit slow (darker), the next one is 1/250s, etc. More will be clear when I make the contact sheets.
I should say that the last time I shot slide film, I didn’t notice any discrepancy, so I concluded that both lenses’ shutters are okay-ish.

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If you made an mp3 recording of your shutter firing at the different speeds and shared a download link to it here, several of us could tell you much more accurately than you can, what the actual speed of your shutters are. Your contact sheet won’t tell you that.

@Ardpatrick You're right, and I appreciate the suggestion, but that’s not exactly what I’m looking for. I hoped my intention was clear from both the thread title and my OP.

As you already did a film test, there’s not much to say about the wisdom of such a test.

Did you double and halve the illumination? Introduce neutral density filters? Or change the f/stop between shots?

miha said:

I'm testing three leaf shutters: two MamiyaSekor lenses with Seiko Shutters and one Schneider lens in a Compur shutter to check exposure consistency across shutter speeds. I'm not trying to confirm if 1/500 is truly 1/500 etc, but rather if it behaves as one stop faster than 1/250, which should be one stop faster than 1/125, and so on. I’ll shoot a uniformly lit white wall and compare exposures, e.g., 1/500 at f/4 should match 1/250 at f/5,6 if the speeds are evenly spaced. For the Mamiya lenses, I’ll use one roll of 120, testing six speeds per lens from 1/500 to 1/15 (I don't need to go lower since I usae the camera mostly hand-held). For the Schneider lens, I’ll use a second roll in a roll-film back, testing down to 1 second (10 shots available). Both rolls will be developed together. Does this approach seem sound, or am I missing something?

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sounds sound and clever to me