If you have ever wondered what the difference between the way a video camera calcualate shutter by fractions of a second and the way a film camera calculates shutter in degrees, then this article by Stuart English at Reduser.net is just for you.

Default Exposure Time - Speed v’s Angles
Following up on the question about exposure time when in ramps, here is a quick comparison of exposure times when expressed in 1 / xx seconds v’s xx degrees. Calculations are at 24 fps.

If you want to convert shutter speed to shutter angles at 24 fps the math is (24 x 360) / Time Fraction i.e 8640 / xx where xx is 1/ xx sec

So the equivalent shutter angle for 1/50 sec shutter speed is 8640 / 50 = 172.8 i.e 172.8 degrees

Sec Equivalent Degrees

1/32 270

1/48 180

1/50 172.8

1/60 144

1/96 90

1/120 72

The camera’s Sync Scan function permits any shutter speed in the range 1/32 - 1/2000 (or equivalent angles) - i.e these are not preset speeds but fully variable.

To find a shutter speed that relates to a known shutter angle, do the math in reverse

At 24 fps it is (24 x 360) / Shutter Angle i.e 8640 / xx where xx is xx degrees

So the shutter speed for 144 degrees 8640 / 144 = 60 i.e 1/60 th sec

Degrees Sec

270 1/32

180 1/48

178.8 1/50

144 1/60

90 1/96

72 1/120

45 1/198

22.5 1/348

11 1/696

8.6 1/1000

So there you go, expect a pop quiz on Friday, now go study. And in the event you suddenly forget the information it will always be right here on FreshDV.com for you to access, now doesn’t that make you feel better. Now quit reading and go shoot something.