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Slow Motion Under 60hz Fluorescent

Published : 15th September 2003


It's been awhile since I have shot film. What should I know about shooting under fluorescent lights when filming at speeds other than 24fr/sec? I am shooting with an Aaton XTR Prod s16. If, for instance I am at 48/fr/secshould I set the shutter opening to 144? How about other speeds say, 32 fr/sec? Also, I don't have an FLD filter, so which stock should I use daylight or tungsten? Does it really matter? Can I count on being able to make the needed color corrections in the video transfer and or color correction on the film prints if we go to a finish on film?

Thanks,

Alan Dater



Alan Dater wrote:

>It's been awhile since I have shot film. What should I know about >shooting under fluorescent lights when filming at speeds other than >24fr/sec?

Use any shutter speed that evenly divides into 120. 48fps at 144 deg., shutter angle gives 1/120 sec., so that is good. For 32 or 64fps., you'd need 192 degrees, which you don't have.

Shoot on 7246 (250D) without filters. It is very tolerant of color mixtures, so mixes of daylight and fluorescent are okay, you can correct for good flesh tones in transfer or print. If you use a tungsten stock you'll probably need to use about 20 magenta on the lens to reduce the excess green.

Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614



Hi

I can't be much help on the first part of the question, although it seems logical to say that as fluorescent flicker is the same as HMI flicker you should follow your HMI safe speed/shutter charts. One thing I can heartily recommend for stock is the Fuji 500 Daylight. I've shot a short on 35mm under very difficult mixed lighting conditions and the fourth colour layer very effectively gets rid of the fluorescent green cast. The other advantage in your situation is that with 500 ASA you will have a lot of room to over-crank.

Good luck

Roger Simonsz
DP
Paris



Alan,

With regard to your query about safe speeds shutter angles, follow this link & you'll be able to get a card for both 50 Hz & 60 Hz.

http://www.cinematographyelectronics.com/index_flickerfree.html

Regards,

James Mc Guire
Gaffer, Dublin



Hi Alan,

If you don't have time to change the shutter angle on the prod you canalso simply shoot at 40 fps rather than 48. It's not as slow but prettyclose and a lot quicker for changing frame rates on-the-go. I agree withthe 7246 recommendation - I find most cool whites are pretty close to 5600 these days and at 40 fps or even 60 fps you'll still most likely have plenty of exposure to work with even shooting available light.

Best,

Stephen McCarthy
Boston



Alan Dater wrote :

>It's been awhile since I have shot film. What should I know about >shooting under fluorescent lights when filming at speeds other than >24fr/sec?

I was just thumbing through David Samuelson's "Hands On Manual for Cinematographers" and he gives the following helpful formulas :

Safe camera speeds with 60hz lighting :

Camera speed in fps = shutter angle / 3 / LPEP

Where LPEP = number of light peaks that you want to capture per exposure
period (typically 2 per cycle, or hz).

Safe shutter angles with 60hz lighting :

Shutter angle = speed in fps * 3 * LPEP

For 50hz power replace 3 with 3.6 in both formulas.

I'm not associated with David Samuelson in any way, other than through this list, so I'm free to say…

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THIS IS A GREAT AND VALUABLE BOOK.

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Art Adams, DP
Mountain View, California - "Silicon Valley"
http://www.artadams.net/