Testing leaf shutter consistency across speeds

[F4U]

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.

 

[Chan Tran]

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?

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.

 

[NiallerM]

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?

 

[wiltw]

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.

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.