78 RPM = 1.3 Hz (rotations per second). That's 3/4 seconds for a full record rotation. Given my initial estimate of 1/16th of a full circle recorded, the exposure time would be 3/64 seconds, which is approximately 1/22 seconds.
Which is pretty close to the stated time of 1/20. :-)
I know someone with an Edison player -- I'll have to keep it in mind for a future challenge ...
Did anyone noticed my blatant mistake in the math? I was writing RPM, but calculating Hz. It didn't even ring any bells after the final result was 1/1250, which is way too short.
Let's fix it. 78 RPM = 1.3 Hz (rotations per second). That's 3/4 seconds for a full record rotation. Given my initial estimate of 1/16th of a full circle recorded, the exposure time would be 3/64 seconds, which is approximately 1/22 seconds.
Excellent one. The subject, the lighting, the colours, the exposure, the depth... Everything works together perfectly. I like how the exposure time is balanced with the rotation speed of the record.
I am not done voting, but this is in my top 2, for now.
Now let's try and guess the exposure time :-)
Let's assume the record rotates with 45 rpm. 1/45 sec would record a whole rotation cycle and blurred the whole label around. I would guestimate that there is a 1/16th of a full rotation recorded here. That would give us 1/720 sec of exposure time.
There is a good chance that this is a 78 rpm record player. In that case the exposure time would be approximately 1/1250 sec.
Of course, there is a chance that the record was turned by hand in which case all math is wrong. :-)
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