Shutter Speed Tester

[Drew Bedo]

I do not know the current state of the art in DSLR video slow motion capture. I haven't used my Nikon D-60 in 10-12 years . . .and it doesn't do video of any sort.

However, I would think that some advanced DSLR models might be able to run a high enough frame rate to get a measurement of the shutter speed of a LF leaf shutter lens. Most LF shutters do not hit anywhere close to 1/1000th of a sec. So any frame rate at or above 1000 FPS could be made to work.

Am I way off base on this?

[r.e.]

I do not know the current state of the art in DSLR video slow motion capture. I haven't used my Nikon D-60 in 10-12 years . . .and it doesn't do video of any sort.

However, I would think that some advanced DSLR models might be able to run a high enough frame rate to get a measurement of the shutter speed of a LF leaf shutter lens. Most LF shutters do not hit anywhere close to 1/1000th of a sec. So any frame rate at or above 1000 FPS could be made to work.

Am I way off base on this?

Sounds like you're talking about using a camera in video mode to capture a large format shutter opening and closing. In theory, it's an interesting idea. As a practical matter, I don't think that there are a lot of hybrid cameras that record at more than 240 frames per second. At a Copal 0 shutter speed of 1/500 of a second (although in practice it won't be that fast), you're talking about the shutter opening and closing in 0.48 of a frame. On a DSLR, you'd need a close-up lens, but the more recent iPhones, and probably some others, will record at 240fps.

For practical purposes, I think that an audio recording, with the waveform displayed on a full computer screen, works fine.

[MartinP]

Using a microprocessor to run a shutter-speed tester seems like massive overkill. My effort was made from a photo-transistor and a few parts to form a switch that goes on with light and off with no light. The photo-transistor is placed on one side of the shutter to be tested, and a torch is put on the other. Power is an ordinary AA battery.

Before use, the output voltage from the device is adjusted to be below one volt, then is plugged in to the microphone socket on a computer of any sort. Any audio editing program (I use Audacity which is a mature open-source program) can then display the waveform and the length of the 'pulse' can be easily measured. It can also output to an oscilloscope, but more people have computers than they do 'scopes of course.

[tomwilliams]

Using a microprocessor to run a shutter-speed tester seems like massive overkill. My effort was made from a photo-transistor and a few parts to form a switch that goes on with light and off with no light. The photo-transistor is placed on one side of the shutter to be tested, and a torch is put on the other. Power is an ordinary AA battery.

Before use, the output voltage from the device is adjusted to be below one volt, then is plugged in to the microphone socket on a computer of any sort. Any audio editing program (I use Audacity which is a mature open-source program) can then display the waveform and the length of the 'pulse' can be easily measured. It can also output to an oscilloscope, but more people have computers than they do 'scopes of course.

Martin, that is indeed a simple solution. I've read that the delays associated with the computer hardware + Audacity software processing are in the low millisecond range, or lower, obviously insignificant given the +-30% accuracy figure that one often reads for LF shutters. For a stand-alone timer that has to handle the processing that your scheme hands off to a microphone circuit and Audacity, a microprocessor is a tidy solution. Especially if an LCD display is wanted with the timer.

LFP user Wally had an idea better than the one I based a tester on - the thread is "Shutter Speed Tester" (25 Nov 2010 post #44).

[Drew Bedo]

Sounds like you're talking about using a camera in video mode to capture a large format shutter opening and closing. In theory, it's an interesting idea. As a practical matter, I don't think that there are a lot of hybrid cameras that record at more than 240 frames per second. At a Copal 0 shutter speed of 1/500 of a second (although in practice it won't be that fast), you're talking about the shutter opening and closing in 0.48 of a frame. On a DSLR, you'd need a close-up lens, but the more recent iPhones, and probably some others, will record at 240fps.

For practical purposes, I think that an audio recording, with the waveform displayed on a full computer screen, works fine.

Yeah . . .the frame rate would have to be around 1,000 fps or higher. Higher frame rates would give better temporal resolution.

I am not sure that a close up lens is necessary. An in focus image is not required I think. DSLARs don't go much above 240fps? I actually have no idea. Maybe it is a technique that could be used to check slower shutter speeds.