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.

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.

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.

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.