[Leica] Ir filter and film cameras, take it off

[jbm at jbm.org (Jeff Moore)]

2007-03-19-02:21:50 Henning Wulff:
> Frank, all the IR hot filters that work by means of interference 
> coatings will do that. Once the incidence angle is too great, the 
> frequency shift causes the colour shifts. No help for it.

So... are the Leica filters essentially the same as the B+W 486?  While
waiting for my official Leica filters to arrive, I've been using a 486
(with the funky reddish/magentaish reflections seen from the front like
some of the Revo sunglasses back in the day) and it does a good job of
cutting out the "gee, what nice purple black jeans you're wearing"
issue under incandescent lights.  I've seen some flare in daytime
situations which might or might not be the fault of the extra piece of
glass...  anyone know if the Leica filters have a multicoated inner
surface?

> Transmission subtraction filters ('dyed' or 'sandwiched') filter 
> don't do that hardly at all, but the cutoff frequency for IR 
> suppression isn't nearly as steep, so aren't that useful in general.

Before my 486 arrived from backorder, I also tried a B+W 489, a proper
normal transmission filter -- it also seemed to work fine at getting the
magenta out, less-steep cutoff or not.  I wonder about what other
tonality corrections one may need to make, though, because these filters
have a slightly greenish tint when you look through them.  But...  if
one were to do a proper fancy ColorChecker calibration of the camera
with one of those bolted on, I assume you could dial that tint out, and
there wouldn't be the need for wacky firmware corner-color twiddling...