On 2011-04-29 08:06:51 -0700, "David J. Littleboy" said:


"John A." wrote:

IIRC there are IR filters that let a bit of visible red through. Might
be a workable compromise.


Most recent digital cameras have very strong IR blocking filters to prevent
color contamination, so very little light gets through and exposure times
are painfully long with most unmodified cameras and an IR pass filter. I
tried that with the 5D, and while the red channel was OK, the green and blue
channels were horrifically noisy. I was worried that I'd see the same thing
even with IR conversion, but with the deepest IR option that MaxMax offers,
the G and B channels, while noticeably lower in exposure than the R channel,
still have enough information that Lightroom can produce decent B&W images.
(The conversion doesn't remove the Bayer filters, and the G and B filters
pass very little near IR, and one or two stops less IR than the R filter
does for deep IR. So I'd recommend forgetting about false color IR and go
for the deepest IR you can get. My opinion, YMMV and all that.)

Lifepixel offers a conversion service which gives the digital
photographer a few more options ranging from their standard IR filter
to "Deep BW IR" filter.
Their other option is replacement of the low pass filter with their
"Full Spectrum Clear" filter, which then requires the addition of
individual filters to your lens of choice.
http://www.lifepixel.com/infrared-filter-choices

--
Regards,

Savageduck