Pressure plate effects on halation

["Rolland Elliott" <rolland_elliott@xxxxxxxxxxx>]

I once replaced the film pressure plate on a N90s with a mirror. The 
exposure difference between the mirror and standard pressure plate was not 
noticible. The main difference was in the amount of halation. I would 
estimate the exposure difference is less than 1/3 of a stop.

Peace, Rolland


>>>I've used both 120 backing paper and black vinyl tape over the pressure
plate shooting Kodak IR Aerographic, and I did not notice a change in
overall density. I suspect there was a change -- your concern makes perfect
sense in theory -- but it was smaller than I expected (or noticed).

The number of stops you lose would depend on how efficiently the pressure
place reflects IR. I assume that my RB pressure plate didn't reflect IR very
efficiently in the first place, which is why I didn't notice a change in
density. (I was trying to hide the pattern of holes on the plate, not reduce
halation.) Very possibly, other pressure plates are much more IR 
reflective,>>>
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