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172.8 shutter angle


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#1 uva_canibal

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Posted 03 April 2006 - 12:14 PM

Hi everibody:
I am a director interested in the quallity of the image. The other day talking with a fellow DP, he told me that in recent times he has been shooting all his material with the shutter at 172.8 angle. This because, he said, it´s the same shutter angle that Kodak´s technicians uses to shoot all the tests for their film stocks. The result it´s a different cadence in motion, and more definition and crisp quality. I really take a look in his material and it was excellent, but I will need a side by side procter and gamble demo, to see the diference, and I´m not have the resources to do that. So here I am, asking to the experts, and anxious to hear their opinions. Thanks!
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#2 Laurent Andrieux

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Posted 03 April 2006 - 03:51 PM

The difference is only that the exposure time is 1/60 s instead of 1/48 (close to 1/50) at 24 fps
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#3 Jonathan Benny

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Posted 03 April 2006 - 04:42 PM

he has been shooting all his material with the shutter at 172.8 angle. This because, he said, it´s the same shutter angle that Kodak´s technicians uses to shoot all the tests for their film stocks.


Your colleague's light meter is most certainly at least 1/10th of a stop off of what the kodak technicians' meters are and therefore I believe he is overstating the significance of the fact that they might be testing at 172.8 (170 degrees according to some of their data).

The difference is only that the exposure time is 1/60 s instead of 1/48 (close to 1/50) at 24 fps


144 (not 172.8) degrees gives you 1/60th of a second at 24fps.

JB

Edited by Jonathan Benny, 03 April 2006 - 04:44 PM.

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#4 Laurent Andrieux

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Posted 03 April 2006 - 05:16 PM

oups sorry, right, 172°8 is even less a difference, it gives you 1/50 instead of 1/48... It's not noticable, for me.

This shutter angle is designed for working with discharge lamps such as hmi on a 50 Hz voltage when runnig 24 fps as to avoid flickering, it should not be noticed as diffrent from 180 °, to me, as a matter of image look...
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#5 Gnanasekaran MN

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Posted 13 April 2006 - 12:48 AM

oups sorry, right, 172°8 is even less a difference, it gives you 1/50 instead of 1/48... It's not noticable, for me.

This shutter angle is designed for working with discharge lamps such as hmi on a 50 Hz voltage when runnig 24 fps as to avoid flickering, it should not be noticed as diffrent from 180 °, to me, as a matter of image look...




I perfectly agree with the views. Idea of using 172.8 shutter angle is to have 1/50 shutter speed when working 24 frames per second, when supply frequency is 50 Hz. and HMI lights are operated with magnetic balast, so that all the frames will receive same exposure (each frame will experience 2 enegry peaks of lgihts equally). If we can run the generator at 48 Hz, the shutter angle can be 180 deg.
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#6 Dominic Case

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Posted 14 April 2006 - 07:18 AM

he told me that in recent times he has been shooting all his material with the shutter at 172.8 angle. This because, he said, it´s the same shutter angle that Kodak´s technicians uses to shoot all the tests for their film stocks. The result it´s a different cadence in motion, and more definition and crisp quality.

Well he's either winding you up, or he's wound himself up.

Any "crisper" quality would arise from the smaller shutter angle giving less motion blur. About four per cent less motion blur. You won't see that.
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#7 Jeff Tanner

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Posted 17 April 2006 - 11:03 AM

My SRII has a 172.8 shutter angle because of its conversion to super 16. The original mirror/shutter was a 180 degree shutter and with the wider gate of super 16 the mirror would not clear the gate long enough for a frame to be exposed properly. That is one reason for a 172.8 degree shutter.

Like Dominic said, the difference in motion blur will not be noticable.

Respectfully,

Jeff Tanner
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