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

AnalogueWendy

AnalogueWendy

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At the weekend I sat and played with the 'Shutter Speed' app (mainly because a new/old camera followed me home from a local charity shop and I wanted to check it out). Shutter speed is a great app to estimate slow shutter speeds, even just with sound.
However, it does not work with the flollopy noises made by Thornton Pickard-type focal plane or behind-the-lens blind shutters. I don't quite feel ready to buy the light gadget to make the shutter speed testing app more accurate. Then I had an idea and tried video.
It worked!
Has anyone else tried this? Is there an app, or a protocol to make it simpler?
(I do agree that accurate shutter speeds on TP shutters are unlikely to be helpful or consistent, but it can be nice to have a starting point for the necessary experiments).
 
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In a word 'no', I haven't used video. How many frames do you get? For 60fps on an IPad video isn't that only 2 frames to check 1/30 sec shutter? When I made a new shutter blind for a TP type roller shutter, I tried sound to calibrate it, but as you say you don't know which noise peaks to measure the stop & start times with. I ended up making an adaptor to hold the TP shutter box onto the lens of a digital camera and then I adjusted the spring on the blind until a digital photo using the blind gave similar exposure to a digital photo using the camera shutter normally. Difficult to explain but it worked OK.
 
The trick was importing the video into a (free) video editing programme.

I put a bright light on the other side of the shutter without a lens in place. Then filmed the video with my phone (cock shutter ->video on ->release shutter -> video off) This gave me a black video clip with the flash of the shutter in the middle.

The video file was opened in Open Shot, which is sufficiently similar to other video software I have used. Once the file was imported I trimmed the clip and then expanded it so I could measure the time it took for the shutter to open and close. This was quite revealing because, as I suspected, the shutter was clearly not moving evenly. (If I get overexposed skies with that shutter I will now know why).

The video software allows markers to be added to clips so I marked the beginning and end of the shutter action and got an answer. Quick bit of maths told me it was 1/25 of a second.

I'm glad to be 'talking' with you about this because I still have lots of questions - particularly about frame speed on my phone. It has a slow-mo setting too which I need to check out. I want to run another set of tests and your questions will encourage me :)
 
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Reginald S. said:
Wendy, what should it have been, from the readings of the shutter scale?
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The scale says 1/30 so I was pleased with 1/25 (assuming I've done my maths correctly).
I can't seem to attach the video here (probably very wise decision by the moderators) I'll see whether I can put it onto a google drive and share the link instead.
 
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The ISO tolerance for shutter speeds is +/- 30% however they are usually much closer to the marked speeds.

Ian
 
That's the file I used.
Have just found that my phone records 30 frames per second so each blip will be 0.03 of a second long. Does this mean that my 1/30 shutter should only be open during one 'frame' of the video?
Just opened the editor again (earlier in the day with my brain working better) and now think the shutter is open for 00,05 of a second, which would make it 1/20th.
@Reginald S. is correct. I need to do some more of these to see how my various shutters really work at slow speeds.
At a tangent - given the emulsions they had available why do any of these ancient blind shutters even have higher speed settings on the dial? I can only think it's the equivalent of VW putting 0-120 +mph on the speedometer of my tiny 1.4 Polo.
Aspirational shutter speeds! :D
 
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I played it at 1/4 speed. I can see a partly open, a fully open and a closing phase.

That might mean the shutter is slow, but should just the fully open phase be 1/30 second ? Looking in Adams it seems the 'effective shutter speed' is from shutter half way open to half way closed. 1 or 2 frames isn't sufficient resolution to see the edge of the blind, so there is a limit to how much can be achieved.

It's amusing to hear it at 1/4 speed !
 
I have a Sony RX100iv that has a ultra fast speed video that last for maybe 2-3 second. But the frame rate can be set to 960fps. If I tried that, how would you set it up?
 
I put a bright light outside my large bellows whole-plate camera on the lens side. The blind shutter sits on the lens board on this camera. Then I held my phone just inside the GG holder to keep it nice and steady. Room lights were off. Routine was cock shutter-> start video -> release shutter -> stop video.
This gave a video clip a few seconds long with the bright flash of the shutter in the middle. Not sure whether the whole video was under 3 seconds.
I trimmed the black ends off the video before importing it to the Openshot video editor.
You would need to use a tripod, but the rest might work in the same way. You might even be able to do the editing and measurements right in your Sony camera.
Let us know how it goes?
 
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AnalogueWendy said:
I put a bright light outside my large bellows whole-plate camera on the lens side side. The blind shutter sits on the lens board on this camera. Then I held my phone just inside the GG holder to keep it nice and steady. Room lights were off. Routine was cock shutter-> start video -> release shutter -> stop video.
This gave a video clip a few seconds long with the bright flash of the shutter in the middle. Not sure whether the whole video was under 3 seconds.
I trimmed the black ends off the video before importing it to the Openshot video editor.
You would need to use a tripod, but the rest might work in the same way. You might even be able to do the editing and measurements right in your Sony camera.
Let us know how it goes?
Click to expand...
So you divide the number of frames lit by 960 to get the fractional in decimals then convert it to a fraction for shutter speed? How do you know that the first and last are fully opened the whole time and not just a fraction themselves?
 
Alan Klein said:
So you divide the number of frames lit by 960 to get the fractional in decimals then convert it to a fraction for shutter speed? How do you know that the first and last are fully opened the whole time and not just a fraction themselves?
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No, I used the Video editor to add markers at the beginning and end of the shutter being open. Then I looked at the timestamps on the markers to measure the time and converted it to a fraction.
Your way might work better, especially if you can view the video frame-by-frame on your camera.
 
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AnalogueWendy said:
No, I used the Video editor to add markers at the beginning and end of the shutter being open. Then I looked at the timestamps on the markers to measure the time and converted it to a fraction.
Your way might work better, especially if you can view the video frame-by-frame on your camera.
Click to expand...
I'll have to try my video editing program. I hope Premiere Elements allows that many FPS. I:m assuming it does otherwise it couldn't play back captured video at that rate. I'll have to test it out.

In the past, I used a sound recording of the shutter and then used Audacity which showed its waveform. I could then see the period and fraction the lens was open. Audacity is a free program on the web. Accuracy kind of fell off faster than 1/60th but was very accurate at slower speeds. I found all of my large format lenses were accurate within 1/3 of a stop (some exactly) at all speeds although it varies from one speed to the next and from one lens to the next. Frankly, I ignore the differences when I'm shooting because they're so close.
 
Alan Klein said:
I found all of my large format lenses were accurate within 1/3 of a stop (some exactly) at all speeds although it varies from one speed to the next and from one lens to the next.
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Ah! You have those fancy modern metal shutters then. I have 2 cameras with fabric blind/spring shutters and the noise they make defies simple wave analysis!
 
AnalogueWendy said:
Ah! You have those fancy modern metal shutters then. I have 2 cameras with fabric blind/spring shutters and the noise they make defies simple wave analysis!
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I don't know for sure. But I believe they're all Copal shutters and since all of the lenses are coated, they are "modern". All are Schneider, Nikor, and Fuji.
 
Alan Klein said:
I don't know for sure. But I believe they're all Copal shutters and since all of the lenses are coated, they are "modern". All are Schneider, Nikor, and Fuji.
Click to expand...

Oh yes, Nikor. Years ago they made those classic rotary trimmers and stainless steel developing tanks and reels. Didn't realize they also made lenses. ;)

(I know you meant "Nikkor", not "Nikor".)

David
 
In the days when there were gramophones, it was possible to put a bright marker onto a record, set it going and make a photograph. As the RPM was known, the time the shutter was open could be calculated. Anything with known, regular motion would work in the same way, presumably.
I’ve not done this myself, only read about it.
 
I have one of these modern grammophones but am not willing to see scary results from measuring my shutters which could shake my faith and probably lead to give up my photography :)

DSCF2568.JPG
 
I've heard of TV screens being used for calibrating shutters, but I'll probably just use the relative brightness of digital longer exposures of the ground glass. Of course the digital exposure must start before & finish after the shutter operation & it's important to block out other light sources.
NB. Digital rather than film to exclude reciprocity failure & variations in processing, but also for ease of assesment...
 
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