Shutter Angle

[digvid]

Do most motion film cameras have a shutter angle of 180 degrees unless stated otherwise? I own a Nizo S56 and the manual does not state the shutter angle, although it does say that at 24fps the equivalent exposure time is 1/57 sec.

- digvid

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[digvid]

Okay then, I guess the math would be:

1/fps * x/360 = 1/T or

x = (fps * 360) / T

where x is the shutter angle in degrees and T is the denominator of the shutter speed.

In my case, the manual says the effective shutter speed at 18 fps is 1/43 and at 24 fps it is 1/57. As someone said above, this works out to about 150 degrees.

(18fps * 360 deg.) / 43 ~= 150 degrees
(24fps * 360 deg.) / 57 ~= 150 degrees

Thanks for the info folks!

- digvid

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[8th Man]

180 degree shutter would give you a 1/48 sec. exposure since 180 is half of the 360 degree spinning shutter disc.
I don't have the formula in front of me but it sounds like your nizo is around 140 degrees maybe? Either way, knowing it's 1/57 sec. is more important for getting metering ect. Actuall shutter angle is a factor when shooting television monitors or bycicle spokes & dollying past fence posts to gain or lose the strobbing effect etc.
The 180 degree shutter must be pretty common since the cine scale on most light meters assumes a 1/48 sec. at 24 fps. Although none of my cameras have 180 shutters.

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PRM

[8th Man]

AHA
the formula was on another post on metering and the math was already done.
150 degrees it is.

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PRM

[crimsonson]

180 is common for 35mm movie cameras (arri, panas, etc.)

Shutter angles is also a factor if you want to meter with great accuracy. However, a 10-15 degree diffrence is neglible. But a 150 and 220 is not (about 1/3 -1/2f stop).


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