Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul D. DeRocco"
<pderocco@i...> wrote:
> > From: John Moody
> >
> > Full conversion includes removal of the Bayer color filter array;
> > not at all
> > easy.  A filter to block the visible light as well.
> > Then, you need to process the raw files without colour
> > interpolation, for a true monochrome image.
> 
> The Bayer filter is built onto the chip as part of the semiconductor fab
> process, so it can't just be lifted off. Although people are
experimenting
> with chemical means of dissolving it, I'm not aware of anyone who's
> succeeded.

Ray Fraser. He hangs around the digital photography forum over at
photo.net. 

He's scraped them off (doing enormous damage) but has finally managed
to successfully disolve one, just this week.

> But if someone does, the more obvious application would be for
> B&W photography, not just IR.

Yup.

> However, even for IR there is some benefit to the Bayer pattern,
because the
> three colors not only have different visible light responses, they
also have
> different IR responses. It's simply not the case than an IR converted
> digicam will show everything in the red channel--the other two
channels also
> carry different images, providing an opportunity for bringing out
different
> features of a scene.
> 
> For instance, my Minolta DiMage 7, which has no IR block filter,
generally
> produces garbage in the blue channel when I put on my R72 filter,
but two
> good but different images in the red and green channels. Not
surprisingly,
> the red channel has the really dark skies, while the green channel
has the
> white leaves. Choosing the proportion of these gives me some artistic
> control over the image that I wouldn't have if the sensor was
monochrome.

We digital IR fans call that "false color".
 
> On the other hand, a monochrome sensor would be much sharper.

Use a Wratten 87 (Hoya RM90), instead of that Wratten 89B (Hoya R72)
of yours, and you'll see true IR monochrome.