Has anyone else used video to measure/estimate focal plane shutter speeds?

It's a bit rudimentary, and obviously bespoke, but I made this 'adaptor' to connect a TP type shutter to a digital camera. I used the Bulb setting so that the exposure started before & after the shutter operation and then compared histograms of 2 photos with and without using the TP shutter. I used 2mm light seal foam to get a snugger fit.

The drawbacks were that the adaptor blocked the low light autofocus illuminator, and there was a bit more weight added to the moving camera lens.

Nick
shutter adaptor 1.jpgshutter adaptor 2.jpg
 
Looks like a handy rig.
Sadly, although I know what an histogram is, I know almost nothing about digital cameras so I don't understand what you did here. Is your histogram a time series? Does it give you a shutterspeed?
 
In this case, it must mean a plot of brightness against time. The thing that digital photographers call a histogram records instantaneous data and changes with time.
I’m afraid I know little about digital cameras. There’s an idiot mode on most of them that’s cleverer than me and my iPhone does a fantastic job. Quite possibly it has an app for measuring shutter speeds. There’s certainly a video facility that can record at different speeds, one of which might be useful.
For myself, I keep my head firmly in the sand on shutter speeds. Almost everything I do seems to be in whole seconds or minutes, so it’s not a major issue.
 
Hi Wendy
I was reading this a few days ago as I wish to test the shutter speeds from my Zeiss Icon Contina.

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How to Measure Your Shutter Speed for Free.

In our lastest video (https://www.youtube.com/watch?v=j-iD_XNpnrg&feature=youtu.be), we discussed the importance of adjusting your exposure based on the actual speed of your shutter. We've even published a handy chart that does the math for you. (See our previous blog post...
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Hmmm… shutter speeds to three decimal places… Yum!

Has anybody checked the accuracy of the aperture? That might be even more interesting and it would affect DoF as well as exposure. As the shape of the opening alters for different f-stops, this might be complicated.
The shape would also affect the rendering of point-source lights, but that’s another matter altogether.
 
The histogram, I think on most digital cameras, is a graph (quantity vertically vs luminosity horizontally) showing how much white and how much black is in the photograph. If the TP shutter is slow the photo will contain more white (overexposed) and the curve will move to the right. And vice versa. It doesn't give a shutter speed, it allows the composition of 2 photos to be compared, one from the digital camera taken at a known shutter speed, and the other using the TP shutter.

In the 3 histogram plots below, the first shows too much black, the second too much white, and the third a good balance. On a roller blind shutter you would move from 1 to 2 by taking spring tension off the take-up roller.
Nick

histogram.JPG
 
The first one shows (perhaps) a histogram for a black cat in a coal-cellar; the second a bride in a snowstorm; the third a normal sort of scene, perhaps a beach, on a sunny day. It can say nothing about shutter speed, as the same exposure and histogram, could be produced by a variety of speed/aperture combinations.
There is, however, as you say, “too much” black or white in the respective histograms - always assuming that the photographer’s intention was to make a “normal” print. Sometimes we might want solid black or white for creative reasons.
 
For the purpose of this test, the aperture is the same for both photos (camera in Manual mode). The only variable is what you adjust - the speed of the shutter curtain.
 
nickl said:
The histogram, I think on most digital cameras, is a graph (quantity vertically vs luminosity horizontally) showing how much white and how much black is in the photograph. If the TP shutter is slow the photo will contain more white (overexposed) and the curve will move to the right. And vice versa. It doesn't give a shutter speed, it allows the composition of 2 photos to be compared, one from the digital camera taken at a known shutter speed, and the other using the TP shutter.

In the 3 histogram plots below, the first shows too much black, the second too much white, and the third a good balance. On a roller blind shutter you would move from 1 to 2 by taking spring tension off the take-up roller.
Nick

View attachment 3711
Click to expand...
You're assuming that the exposure is set correctly.
 
Surely, all these three histograms, if they are from a ground glass screen during exposure, show that the illumination is uneven. A perfectly uniformly-lit screen would show a single high peak and if the exposure is correct it would be in the centre on Zone Five. But it wouldn’t tell anything at all about shutter speed.
 
David M said:
Surely, all these three histograms, if they are from a ground glass screen during exposure, show that the illumination is uneven. A perfectly uniformly-lit screen would show a single high peak and if the exposure is correct it would be in the centre on Zone Five. But it wouldn’t tell anything at all about shutter speed.
Click to expand...
Indeed it doesn't directly tell us anything about shutter speed.
However it might be used to relate the current shutter speed/aperture to the metered light and with a range of apertures/light levels indicate how consistent shutter speeds are with each other. This is nearly always more important than the actual values.
Apertures should be more accurate than shutter speeds (especially from Thornton Pickard shutters), but I know manufacturers can be optimistic particularly at the wide open end
To be meaningful I think a uniform subject & consistent illumination is needed.

Of course for those just interested in taking photos histograms from digital cameras can be used to find the right shutter setting irrespective of what the actual speed is, but that's a different matter than this thread is discussing.
 
Petrochemist said:
Indeed it doesn't directly tell us anything about shutter speed.
However it might be used to relate the current shutter speed/aperture to the metered light and with a range of apertures/light levels indicate how consistent shutter speeds are with each other. This is nearly always more important than the actual values.
Apertures should be more accurate than shutter speeds (especially from Thornton Pickard shutters), but I know manufacturers can be optimistic particularly at the wide open end
To be meaningful I think a uniform subject & consistent illumination is needed.

Of course for those just interested in taking photos histograms from digital cameras can be used to find the right shutter setting irrespective of what the actual speed is, but that's a different matter than this thread is discussing.
Click to expand...
You could use a gray card to fill the entire view. Then you'd get a narrow histogram that would be in the center if the exposure is set correctly. I don't think it's fine enough though to determine shutter accuracy.
 
Alan Klein said:
You could use a gray card to fill the entire view. Then you'd get a narrow histogram that would be in the center if the exposure is set correctly. I don't think it's fine enough though to determine shutter accuracy.
Click to expand...
Grey card, paper sheet or a blank wall should all work as long as they fill the FOV & have even lighting.
How accurately do you need to check your shutter speeds? I'm reasonably confident an error of 1/3 stop could be spotted via this sort of procedure, but I'm not sure if it would be noticeable in my photography.
 
shop.stearmanpress.com

How to Measure Your Shutter Speed for Free.

In our lastest video (https://www.youtube.com/watch?v=j-iD_XNpnrg&feature=youtu.be), we discussed the importance of adjusting your exposure based on the actual speed of your shutter. We've even published a handy chart that does the math for you. (See our previous blog post...
shop.stearmanpress.com

Might be worth a moment's attention.
This is our old friend who makes the Stearman 445 developing tanks, doing much the same thing.
My rather basic iPhone does what they call Slo-Mo at 240 frames a second. I'd assumed that every phone would do that. But I also assume that everyone else is using an iPhone anyway.
I'm afraid I know nothing about video software.
 
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