How to get 1/50 shutter speed?

I

ian_h

Active member
I'm a GH13 user, and have been using an AF100 for a shoot for the 1080p slowmo. I'm shooting in 59.94hz to get 60p conforming to 23.98 frame rate for the best slow motion. My problem is that I only get 1/60 shutter instead of 1/50 shutter on the shutter wheel at the back of the camera, and it's giving me terrible flicker from street lamps at night (I'm in South Africa, which is a 50hz country).

Is there a way to shoot 23.98 (overcranked to 60p) and still get a 1/50 shutter? Not sure I understand the synchro scan options...
 
No, and if you tried to do that it would be disastrous for your shoot.

If you try to set the shutter speed to slower than the frame rate, it will not do what you want -- it'll instead cause the system to drop frames. 1/50th at 60fps is impossible -- the bare minimum shutter speed possible at 60fps is 1/60th.

If you're shooting overcranked 60p, you want 1/120 shutter for motion; if that's causing problems with the lights then you should either use 1/100, or not go to 60fps, go to 50fps instead.
 
Thanks Barry, but is there a way to get 1/100 shutter on the AF in 60p overcrank? I can only see 1/120 option. Ideally I'd like to get the extra 20% slowdown that 60p gives over 50p.
 
Uh... well... yes, you probably could get it. You'd probably have to go in the syncro scan and set it to (let me break out my abacus...)

I think 214 degrees would do it.
 
Yep, looks like 214 degrees

abacus3.gif
 
Barry_Green said:
...(let me break out my abacus...
Click to expand...

Everything I shoot is 24P so I've been using a shutter angle of 172.8 degrees when filming in countries with 50 Hz lights.

I've kept this same shutter angle for 48 fps, but am not sure this is ideal, so would love to know how to calculate these values.

Thanks,
Bern
 
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Exposure time = 1 / ((360 / shutter angle) * frame rate)

So, the exposure time for 172.8 degrees at 24fps = the reciprocal of 360/172.8 * 24.
 
Barry_Green said:
Exposure time = 1 / ((360 / shutter angle) * frame rate)

So, the exposure time for 172.8 degrees at 24fps = the reciprocal of 360/172.8 * 24.
Click to expand...

Bern Caughey said:
Everything I shoot is 24P so I've been using a shutter angle of 172.8 degrees when filming in countries with 50 Hz lights.

I've kept this same shutter angle for 48 fps, but am not sure this is ideal, so would love to know how to calculate these values.

Thanks,
Bern
Click to expand...

Which, according to my math 172.8 degrees is 1/50th @ 24fps, 1/100 at 48fps, and 1/125 @ 60fps...

Barry_Green said:
I think 214 degrees would do it.
Click to expand...

With all due respect, I think you may have a slight mis-calculation, as to get 1/100 @ 60fps, according to my ol' number cruncher, you would need to use a 216 degree shutter angle. I found 214 degrees to put me at almost 1/101.
 
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