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Question about shutter speed?


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#1 Michael Ryan

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Posted 27 August 2007 - 04:45 PM

Hello All,

I have a Bolex H8 Reflex. I'm shooting with Kodak Ektachrome 100D reversal film. I'm shooting at 24 fps which gives me a shutter speed of 1/112.

I don't have a hand held light meter, but I do have my 35mm still film camera that has a built in light meter. The trouble is I don't have a 1/112 on my still camera, the closest shutter speed is 1/125.

My question is can I use the F stop reading on my still camera (set at 1/125) for my Bolex? I'm thinking that the difference between 1/125 and 1/112 is so small that it won't make a difference?

Thanks for your help.

Mike
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#2 Toby L Edwards

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Posted 27 August 2007 - 05:16 PM

You should be fine. Just make sure your using a similar focal length lens, or get closer or futher from your subject to match your framing on the 8mm lens. Your 35mm SLR meter is like using a spot meter. You should be able to adjust your shutter spead between markings. That might depend on your camera? At any rate 112th to 125th is close enough.
Just my opinion.
Good luck. 100D is a really nice reversal stock.
Toby
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#3 Nick Mulder

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Posted 27 August 2007 - 05:23 PM

In lieu of a proper meter its close enough for rock and roll yes (even for reversal) - and a little over exposure never hurt anyway...

I'm interested though where did you get the figure for the exposure ? - do H8's also have a 135deg shutter angle like the RX windup H16's ? In which case the exposure would be (1/24)*(135/360) = 1/64sec physical... then taking the prism into account >> approx ~1/75sec relative
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#4 Michael Ryan

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Posted 27 August 2007 - 07:26 PM

In lieu of a proper meter its close enough for rock and roll yes (even for reversal) - and a little over exposure never hurt anyway...

I'm interested though where did you get the figure for the exposure ? - do H8's also have a 135deg shutter angle like the RX windup H16's ? In which case the exposure would be (1/24)*(135/360) = 1/64sec physical... then taking the prism into account >> approx ~1/75sec relative



Hello Nick,

My Bolex H8 Reflex was made in 1962 and has a variable shutter. The front of the manual has a very extensive table for all shutter speeds for all the different frame rates and also the different shutter settings. It also includes the shutter rates with and without the Bolex reflex prism system included. It's quite a list!

I had used this 35mm camera light meter method for another movie camera and the results were very good.

I had never thought of the focal lenght issue before. I imagine it wouldn't really make a big differnece unless the movie camera had a very long focal lenght. My still camera has a 50mm lens.

If anyone is great with math out there, how many tenths of a second could you go before it would make a difference? We might need David Mullen for that...


Mike
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#5 Alessandro Machi

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Posted 30 August 2007 - 03:08 PM

Hello All,

I have a Bolex H8 Reflex. I'm shooting with Kodak Ektachrome 100D reversal film. I'm shooting at 24 fps which gives me a shutter speed of 1/112.....
Mike


This is a very uncommon shutter speed and shouldn't be used for other Super-8 cameras. For instance, A Canon 1014XLS would have two shutter speed options at 24 frames per second, one would be approximately 1/40th of a second, the other would be approximately 1/60th of second.

Now if one wanted to factor in the loss of light that is diverted to the viewfinder, one could add that to the shutter speed and end up around either 1/60th of a second or 1/90th of a second for light meter calculation purposes. My numbers are approximations, but I think they are close.
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