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65mm 8-perf Movement Run Time

65mm 8-perf

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#1 Christopher Lew

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Posted 15 August 2017 - 06:08 PM

Hello,

 

I couldn't find a 65mm forum so I thought I would share this here. 

 

Does anyone know the formula to calculate the amount of time a 1000' mag of 65mm film would run with an 8-perf movement?

 

 

Chris 


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#2 Dom Jaeger

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Posted 15 August 2017 - 06:55 PM

Almost 9 minutes according to the Kodak film calculator:
http://www.kodak.com...tor/default.htm

The formula is simply how many frames fit in 1000 ft divided by fthe frame rate - 12800 frames at 24 per second.
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#3 Gregg MacPherson

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Posted 15 August 2017 - 07:35 PM

I think 65mm has the same perf pitch as 35mm so a quick answer would be half the run time of 4 perf 35mm.  So about 5.58 minutes per 1000'.

 

If you want to check your algebra...  

 

the camera perf pitch is 0.1866" or 0.01555'

so 8 x perf pitch is 0.1244'

@ 24fps this is 2.9856 ft/s

so 1000/2.9856 =334.9s or 5.58mins run time per 1000'.

 

Dom,  I didn't see your post.  Now I look a pedantic type.  Your 9mins sounds off though.

Is an 8 perf 65mm movement one of the old unusual ones?  I couldn't see much about it.  Saw a short article about someone shooting a project on this format,  but not much else.


Edited by Gregg MacPherson, 15 August 2017 - 07:42 PM.

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#4 Gregg MacPherson

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Posted 15 August 2017 - 08:02 PM

I see now.  They only have one option for 65mm which is 5 perf.

There perf totals have a small error also,  unless I am wrong on the pitch.  

 

There are 64309 perfs in a 1000' roll.

so 64309 divided by 8 then by 24 gives 333.33s or 5.55mins.


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#5 Tyler Purcell

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Posted 15 August 2017 - 08:14 PM

8 perf was used a few times to create a more normal vertical operating camera with a square frame out of 65mm film stock.

I believe some movie rides used it, but more importantly IMAX did as well. I'm not sure how many shows were shot with the format, but it's never been popular with anyone.
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#6 Dom Jaeger

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Posted 15 August 2017 - 08:54 PM

Ah sorry, 8 perf not 5 perf. That's a weird one!

I guess you could just multiply the Kodak calculator result by 5/8.. so around 5 1/2 minutes as Gregg said.

Kodak does round the numbers off a bit, might be some seconds off over 1000ft.
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