Hmi Safe Shutter?

[Danish Puthan Valiyandi]

I'll be shooting a Musicvideo- using the 16mm Arri SR-3.

Giving easily the possibility to change the Shutterangle- the director wants

me to shoot with an 45° angle.

Anyway- being honest I never shot 45° before :)

 

Using the rule- Hmi lamps at 50Hz- it wouldn't be a problem shooting

with 45° and 25 fps(?)

 

Anyway.. I'll be also using Kinoflos... will that be a problem?

 

Thanks in advance for your answers :rolleyes:

 

Greetings,

Dan

Edited May 26, 2005 by Danp

[David Mullen ASC]

The problem with a 45 degree shutter is not FLICKER but EXPOSURE.

 

Under ordinary AC lights cycling at 50 or 60 hz, with such a short shutter speed, you may catch the pulsing light at the bottom, middle, or the top of the sine wave each time you roll. So you won't get frame-to-frame exposure fluctuations (flicker) but one take may be dimmer than another. With a normal shutter angle, you usually catch two to two and a half pulses per frame. But with a 45 degree angle, you are only catching part of a single pulse each time.

 

However, with high-frequency AC lamps like Kinos or an HMI on flicker-free mode, it should not be a problem.

[Danish Puthan Valiyandi]

Thanks David, I appreciate your answer.

That's everything I wanted to know :)

 

 

Greetings,

Dan

[Bob Hayes]

I've been shooting in Thailand at 50 cycle hmi in flicker free mode at all speeds and 45 degree shutter no problem. Kinos had no problem either.

[Bob Hayes]

David:

 

Are so saying that regualr Tungsten may have exposure differences take to take with a 45 degree shutter?

 

Bob

[David Mullen ASC]

David:

 

Are so saying that regualr Tungsten may have exposure differences take to take with a 45 degree shutter?

 

Bob

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No, just AC discharge type lamps that pulse at 50 or 60 hz.