IR contamination and B&W photos

[Cruewell]

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I read in some M8 review that the same IR sensitivity problem that creates the magenta cast also increases tonal depth and richness of blacks when the pictures are converted to B&W.

 

Is there any truth to this? If so, pictures to be converted to greyscale should be taken with or without the IR filter? And does the conversion to greyscale need to be done in a particular way?

[Woody Campbell]

Sean Reid has written on this subject with extensive examples.

[ennjott]

But what he writes isn't public.

Yes, it can improve B&W tonality. Some B&W films are sensitive to IR too.

[ho_co]

Jose Luis--

To make an over-simplified example: Simply put, some surfaces reflect more IR light than others. And some of those surfaces are what our eyes see as black. So, looking at a black dress, what we see as, say, three shades of grey, the M8 might see as seven shades of grey because of the admixture of IR.

 

That is, since monochrome is already an abstraction, the IR might enhance a B&W image, whereas with color the M8 sees IR as red, making the colors look "wrong."

 

The people who make this argument generally point out that not everyone might agree, but that they personally have responded this way to B&W images from the M8 without IR filtration.

[scho]

Tonal range is limited in B&W IR, particularly in the midtones, but otherwise can be quite beautiful. I use a modified Canon 350D for IR work (removed AA/IR cut filter from sensor and replaced with 715 nm IR pass filter). Examples:

http://www.pbase.com/scho/ir_rebel&page=all

[j. borger]

I use no filter for B&W on the M8 exactly because of the reasons mentioned: more tonal separation.

So what i basicaly get with the M8 and it's IR sensitivity is a B&W raw file with lots of information and more different tones... it often needs more postprocessing though .... local contrast enhancement, dodge & burn get me to the final image ......