[Tig] ND for Grading Suite Projector

Jim Houston jdhouston at earthlink.net
Thu Oct 15 12:45:10 BST 2009


This is a common problem in small rooms even with as low as a 1600w  
lamp.

However, best thing to do is not to use ND but adjust the 'gain'
setting in the projector setup.

ND filters always cause some flare with a loss in contrast and  
sharpness.

Adjusting the gain from 1.0 to say 0.8 will slightly change the gamma  
which you can fix
in a lookup table, but you can nail your target brightness.  (You are  
also giving up
about half a bit in the electronics (so 10bits-->9.5 which isn't  
usually visible).

[If you really are pushed into NDs, use a glass 6x6" filter (pricey)  
tilted at an angle
of 45 degrees from the light path and at least 8" from the lens  
surface.  The first
reflection from the ND filter should not bounce back into the lens]

Jim Houston
VP Technology and Engineering
Sony Pictures Entertainment





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