[Leica] How IR filters affect M8 B&W

[henningw at archiphoto.com (Henning Wulff)]

>I'd assume that the firmware setting of whether the IR filter is on 
>or off may have an effect on the camera interpolation as well - yes? 
>no?
>
>Fond regards,
>George
>george@imagist.com
>www.imagist.com
>http://www.imagist.com/blog
>Picture A Week - www.imagist.com/paw_07
>

George, the only things that the firmware setting does is compensate 
for cyan drift and vignetting. It can't compensate for spectral 
responses beyond the usual white balance corrections, ie, global 
changes.

So setting the firmware 'incorrectly' will cause vignetting oddities 
which will be readily evident for lenses which show significant 
vignetting, and slight tonal difference due to spectral response 
differences in the corners, again with wide angle lenses, but not 
other effects.

Just as too high IR response due to shooting without an IR filter 
cannot be corrected completely in post-processing in colour shots, 
neither can tonal changes such as Peter has shown be compensated for 
in firmware, which is of course a type of post processing.

BTW, I've tried some of the same kind of shots as Peter, and gotten 
exactly the same results to my satisfaction. They weren't really 
processed for posting, but gave me enough to cause me to leave the IR 
blocking filter on unless I really want the high-red/IR look. You can 
enhance it substantially by using an orange, or even red filter.


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