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Silicon Imaging SI-2K
2/3" 1080p IT-integrated 10-bit digital cinema w/direct-to-disk recording.


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Old September 15th, 2010, 11:14 PM   #16
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Dennis and Hien, if you are around, here is a theortical query for you.

Have you been told any experiences relating to infra-red contamination of images when deep ND filtering is used with groundglass devices?

Mixed visible and IR sources have a very significant negative effect on tube-based night-vision as far as image clarity is concerned. My imagining is that the same might apply over the much longer optical path via adaptors and that maybe IR light-loss through the adaptor path may be also less than for visible light.

Last edited by Bob Hart; September 15th, 2010 at 11:14 PM. Reason: error
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Old September 16th, 2010, 02:05 PM   #17
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Bob, I've observed some very strange things with regard to ND filters and IR, particularly on our EX1 (another CMOS camera!). With the SI-2K, and Ari's advise regarding IR, I'm guessing there's a very good chance that something interesting is going on outdoors.

The chart looks good.

Cheers,
Dennis.
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Old September 28th, 2010, 09:30 AM   #18
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Now the flu is done and dusted and I am only half-dead, I thought I'd get one of the hard bits over first and try the relay in low light in a less well lit corner of the Armadale Retail dragstrip.

The relay was wide-open to provoke any softness it might have. The lenses were Noct-Nikkor 58mm f1.2 and Nikon 28mm f1.4, both backed off into a sweeter spot than wide-open. Camera gain was set to 0db. It is all about not being a fair test. I only shot 0db. I was getting some unwelcome attention from some people in a car across the road out of the shot. So I did not shoot at higher gains but packed up and left. It is a bit of a crimmy neighbourhood. I think they thought I might have been running a speed-camera, something I have been confronted with previously.

Here are a few grabs, two standard, two pushed in post. In the pushed grabs, I dropped the blue channel quite a lot. The camera white-balance was set to 3200K.

Given the hostile conditions, it seems to be resolving quite well.
Attached Thumbnails
Researching likely 35mm adaptor use on SI2K.-brevis-lowlight-07.jpg   Researching likely 35mm adaptor use on SI2K.-brevis-lowlight-08.jpg  

Researching likely 35mm adaptor use on SI2K.-brevis-lowlight-pushed-03.jpg   Researching likely 35mm adaptor use on SI2K.-brevis-lowlight-pushed-04.jpg  


Last edited by Bob Hart; September 28th, 2010 at 09:53 AM. Reason: added grabs
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Old October 28th, 2010, 02:56 PM   #19
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I have just received the True-cut IR filter so will resume my tests with the Cinevate varifocal relay. I will also try it with the anti-aliasing filter removed as it is expected that the groundglass itself, with a notional 5 micron "grain" over an approx 27,000 micron groundglass screen width will perform that function.
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