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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

variable shutter speed?

Joofa said:
JT,

Please refer to the following graph, in which I have drawn integration time (exposure time) increasing on the x-axis and on y-axis is its effect on the amplitude of the corresponding "banding" because of flicker.

7051_1207022599.gif


As seen, "flicker free" are those exposure times where the red line meets the blue line. In between values are where one sees the flicker and its magnitude varies. As seen, the magnitude of flicker decreases (even when not zero) as integration times increases (to the right).

BTW, since you are in Austin, you are most welcome to drop by any time and we can discuss such topics of interests.
Click to expand...

very cool, so it's really a question of sync -- you can choose longer or shorter intervals, so long as you pick a good point on the x-axis? also, what is the unit of measure you are using there? (the chart doesnt specify it)

JT
Austin, Texas
 
jtcoleman said:
very cool, so it's really a question of sync -- you can choose longer or shorter intervals, so long as you pick a good point on the x-axis? also, what is the unit of measure you are using there? (the chart doesnt specify it)

JT
Austin, Texas
Click to expand...

The points where blue and red lines meet are at: n / (2 * f). For US it will be:
n/120, with n = 1, 2, 3, ..., i.e., 1/120, 2/120 (=1/60), 3/120 (=1/40), ...

The interesting thing is as seen in the graph the amplitude decreasing with increasing exposure time, so even if you are off from n/120, but your exposure time is large enough, the amplitude may be small enough and not affect.
 
Ok, I can't get a 180 degree shutter at 36fps, Tungsten even Flickers, The only fix is shooting 1/60th, but then you need another 1/2 stop, and if it is a ramping Shot, a Iris Pull needs to be made to match the exposure change. Since Relative mode flickers under about any light at 36fps it cannot be used, the banding is much more prominent and changes speeds and sizes and directions over each shutter angle.

Unfortunately is this the disadvantage of a cmos sensor? only having 24, 30, and 60 seems limited.
 
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