Could speed of shutter faulter on change of aperture - Please read post it explains

jollyjack

jollyjack

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Jon
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I have be set a task to check my camera's shutter speed. I am using a turntable with a record that has a white line on it and rotating it at 33 1/3 speed.

I set camera at a set aperture and alter the shutter speed and then measure the arc in degrees the minus the lines thickness in degree's then degree/200 which gives me my shutter speed in deciminal.

1/15th sec is 0.0666

i have done this at two aperture settings f/5.6 which was very close to the correct reading then f/10 the readings were again close untill i got to 1/6th sec where i show a drop from 0.16 which is correct figure and the reading i got at f/5.6 to 0.145 for f/10

QUESTION

Should i see a drop in shutter speed on my D90 whilst increasing the aperture or should i put it down to record player/incorrect reads.

Checked angles lots of times now.
 
Is this the sort of thing Nikon shooter do in their spare time, no wonder its known as the dark side :D

Sorry mate cant help you with your question :shrug:

Steve
 
one way to test it could be:-

You know it should be revolving at 33 1/3 rpm so using an aperture you were happy with, set the camera to take an image with a fast shutter speed at the correct interval to correlate to a 360 deg revolution. By my maths (which are rubbish!) it's 199.8 deg per sec so 360 deg should be 1 sec, 48 ms . Make a mark on the record at top dead centre and see if it is in the same position on each revolution. That should monitor the speed of the turntable for you and show any variation.

Now, who has a high speed camera that we can set 1 sec and 48ms as an interval between shots?

Extrapolating that up though every 5 revolutions should give you an interval of 9 sec so you could monitor the turntable speed every 5 revolutions without too much difficulty :) That should help to eliminate one possible variation.

Ah Nikon geeks truly have inherited the earth ;)
 
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Thanks AliB

AliB said:
one way to test it could be:-

You know it should be revolving at 33 1/3 rpm so using an aperture you were happy with, set the camera to take an image with a fast shutter speed at the correct interval to correlate to a 360 deg revolution. By my maths (which are rubbish!) it's 199.8 deg per sec so 360 deg should be 1 sec, 48 ms . Make a mark on the record at top dead centre and see if it is in the same position on each revolution. That should monitor the speed of the turntable for you and show any variation.

Now, who has a high speed camera that we can set 1 sec and 48ms as an interval between shots?

Extrapolating that up though every 5 revolutions should give you an interval of 9 sec so you could monitor the turntable speed every 5 revolutions without too much difficulty :) That should help to eliminate one possible variation.

Ah Nikon geeks truly have inherited the earth ;)
Click to expand...
 
To be honest the aperture is a lens function and the shutter is a camera function and if it is performing at 1/15 steadily at other apertures i can see no other reason for the increased variation at f10. My bet is on your record player ;)
 
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are you lighting with daylight?
the strobe effect of mains lights may be a factor? :shrug:
 
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