When HD first hit the big time Optex introduced a Longitudinal Colour Corrector, which was said to make film lenses useable on HD cameras by changing the way the light was focussed on the 3 CCDs (with film lenses it focusses to a single plane only). Now at the time I thought it was a load of tosh and just a way to make money by selling something that we don't really need. Anyone have much experience with using one though? I've used Canon 300 and 150-600 on Sony 750/Varicam and thought the images looked OK, but just wondering if I'm missing something?
Steve

No experience with it, but I'm with you on the 'tosh' wagon.

There's a very good seminar on HD optics and sensors by John Galt, Head of Advanced Digital Imaging at Panavision, and Larry Thorpe (Canon Broadcast): Demystifying Digital Camera Specifications
(http://media.panavision.com/ScreeningRoom/Screening_Room/Demystifying_Part1.html)

It gives a good overview of the challenges for HD glas, touches on 1 vs 3 imager system, bayer sensors and on how MTF really defines system quality over the different comonents.

I can wholly recomend it.

George/

Thanks George, I've seen it via a link on REDUser. I agree, it's well worth a look if only to give an overview of general principles.
Steve

I'm sure there are very few people interested in this, but I tried the LCC at last on my Canon 150-600 lens on Varicam HPX2700, and if it made any difference at all I certainly couldn't see it. Did big blow ups in FCP and they looked virtually identical with and without the device.
So there.
Steve

If you have CA issues it can help if you make the blue channel slightly smaller than the red and green channels. There aren't many edit packages that allow you to do this without a plugin though. It mimics and reverses what is happening in the lens to some degree. In most types of glass blue is refracted more than the rest of the spectrum.