HVX Shutter Angle / Shutter Speed Chart?

B

Brian_Broz

Active member
Hi,
Sorry but I'm still a little confused on how to calculate shutter speed based on what shutter angle you are set at.
I understand @ 24P 1/48th shutter speed = 180 degree shutter
Has anyone seen a chart comparing shutter speeds and shutter angle? I think this would be handy to have on location. So I can fool everyone and look like I know all the answers :-)
For example, if I'm shooting at a 280 degree shutter at 24P, what shutter speed is that? Or 120degree shutter at 30P etc...
If anyone could point me in the right direction, that would be great!
Thanks,

BBroz
 
you dont need a chart - you need math

180 degree means 1/2 of a circle because 360/180 = 2

so the shutter speed is 1/2 of the reciprocal of the frame rate - so if your frame rate is 24 your shutter is 1/2 x 1/24 = 1/48 - if your frame rate is 30 your shutter is 1/2 x 1/30 = 1/60

Another example - 270 degrees is 3/4 of a circle

so the shutter speed is 3/4 of the frame rate - if your frame rate is 24 your shutter is 3/4 x 1/24 = 3/96 or 1/32 - if your frame rate is 30 your shutter is 3/4 x 1/30 = 3/120 or 1/40

i hope my math is right
 
A chart would be nearly impossible to calculate, seeing as you've got about 700 different shutter angles and a dozen different frame rates and the shutter speed is different for all those combinations.

So it's best to just rely on the formula.

And the formula is: shutter speed = 1/(360/shutter angle) * frame rate.

So for 180 degrees and 24fps, it becomes:

1 / (360 / 180) * 24, which = 1 / 48.

For 200 degrees at 24fps it's 1 / (360 / 200) * 24, which = 1/43.2

For 350 degrees at 2fps it's 1 / (360 / 350) * 2, which = 1/2.06
 
this may sound like a stupid question but i'm kinda behind on a lot of things...

what exactly does changing the shutter angle do for the image? i understand that if its 180 degrees then for the first half of the(say you're shooting @ 24fps) 1/48th of a second the shutter is black and the other half, the shutter is exposed??

but by making it 270 degrees and having it exposed for 3/4 of the 1/32(if that's how it works?) what is the essentially doing for/to the image?
 
Owen,

That calculator is great! But I was wondering, if you might be able to build it so that I can enter in the shutter speed I want, say frame rate and have it spit out the shutter angle?

But many thanks for that. It has already helped.

Ben
 
If I'm shooting in a darker room at 720/24pn and have the iris open as much as I can, is 1/48 still what I should be shooting at or would dropping it down even more result in too much blur or a loss of quality?

Sorry, I'm trying to understand this as well (math was never a good subject for me).

I just can't go below 1/24 in terms of syncro scan if I'm shooting at 24p, yes? Or am I waaaaay off in assuming this? Or is it 1/30 that you can't go below?

TIA,
Dale
 
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The more you open up the shutter, the more light you'll get, and the blurrier your image will become. If it's a talking head or something, you might find 1/24th acceptable. For anything with motion in it, 1/40th is about as low as you'd typically want to go; maybe 1/36th.
 
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