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-   -   Shutter angle (https://www.dvinfo.net/forum/silicon-imaging-si-2k/92092-shutter-angle.html)

Bob Grant April 22nd, 2007 04:48 AM

Shutter angle
 
Currently the only options seems to be 180deg or less. Any plans / possibility of going to 270deg shutter angle (or more)?

Jason Rodriguez April 22nd, 2007 11:44 AM

There is a long shutter mode in the camera . . . we weren't showing it on the show floor since the feature is in beta, but you can get very long shutter times with that feature.

Bob Grant April 22nd, 2007 02:48 PM

Excellent.
Just a suggestion. Looking at the camera I saw that shutter time was set as speed, I think changing it to angle or having angle / speed as an option would be a nice feature so those coming from sprockets would feel at home.

Noah Yuan-Vogel April 30th, 2007 12:09 PM

I asked about this at NAB, and Ari reminded me that the camera is actually shooting at 48fps and dropping every other frame, so more than a 180degree shutter is impossible in the normal "24fps" mode since 1/48th sec is actually a 360degree shutter in the camera (and to be asking for a 360degree shutter would actually be asking for 720 degrees).

So there is a long shutter mode? Does this mode then run the sensor at half the normal (double) clock?

Jason Rodriguez April 30th, 2007 08:38 PM

No . . . the sensor clock is still running at normal speed, but it is accumulating frames rather than reading out at the end of the frame and integrating a new frame . . . if we were to simply slow down the processor clock, that would slow down the read-out rate, and you would get horrible rolling shutter skew effects.

Noah Yuan-Vogel April 30th, 2007 11:40 PM

Yeah, thats what I would have been worried about. However it is still unclear to me where the line between horrible and acceptable rolling shutter artifacts is as I haven't actually shot seriously with a camera that exhibited such artifacts (just experimented). Then again with that much motion blur rolling shutter might not be so noticeable? Any issues with the look of the motion blur if there are two separate integration periods for each frame? No break between the two? Can it do shutters like 270degrees alright? I guess with the right programming anything is possible, eh?

Now all you need is to program it to readout and accumulate at the same time so it reads out several times during exposure and combines the images into new 16bit cineform raw HDR video... kidding

Noah Yuan-Vogel April 30th, 2007 11:45 PM

Come to think of it, does that mean at 720@72fps the sensor is actually clocked for 144 fps?

Jason Rodriguez May 1st, 2007 08:38 AM

No . . . past 30fps we stop dropping every other frame because at 60fps and up you're not getting the rolling shutter issue since the read-out is fast enough.

Theoretically we could clock up to 144fps, but it doesn't necessarily gain anything


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