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Time lapse exposure compensation


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#1 Drew A Daniels

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Posted 03 September 2008 - 07:32 PM

hi, i plan on shooting some various time lapses this weekend with an Arri SR2 and a variable speed controller.
Do i need to compensate if i shoot a slow frame rate like 1 frame every 5 seconds or so?
Would i need to close way down and compensate or is it like shooting a still photograph with a normal exposure? i've never shot time lapse on 16mm so any advice would help. thanks

Drew
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#2 David Rakoczy

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Posted 03 September 2008 - 09:43 PM

Which Speed Control will you be using?
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#3 Serge Teulon

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Posted 04 September 2008 - 03:44 PM

Yes you do need to compensate.
Essentially what happens in moving photography when you undercrank, is that each frame passes through the gate at a slower speed. The equivalent in still photography is when your mirror/shutter remains open for a longer period of time.
For example, if you take an exposure reading of, say, T2.8 @25/24fps and then if shooting @ 1fps you would need to close up to T11 1/2.

S
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#4 timHealy

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Posted 06 September 2008 - 02:20 AM

Would you need an intervalometer rather than a speed control for 1 frame every 5 seconds? Maybe it depends on the speed control.

I also seem to recall that the SR may not be able to do 1 frame per second on its own. Cinematography Electronics sells and installs a single frame chip that works with their speed control or intervalometer. At least the SR one and two needed the chip. Just some questions you may want to ask.

Best

Tim

Edited by timHealy, 06 September 2008 - 02:23 AM.

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#5 John Brawley

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Posted 06 September 2008 - 04:34 AM

hi, i plan on shooting some various time lapses this weekend with an Arri SR2 and a variable speed controller.
Do i need to compensate if i shoot a slow frame rate like 1 frame every 5 seconds or so?
Would i need to close way down and compensate or is it like shooting a still photograph with a normal exposure? i've never shot time lapse on 16mm so any advice would help. thanks

Drew



It's my understanding it's technically very difficult to do anything less than 3 fps with an SR2. If you want to go to 5 second intervals, you will also need a capping shutter of some kind, as the SR shutter won't be light tight enough to prevent fogging while the frame parks and waits to be exposed.

jb
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