Andy,
My 17-40 F4.0 L lens has a square slot on the camera end for a thin
filter. Could I cut a piece from the unexposed end of a roll of
slide film and use that?
Roger
On 16 Feb 2008, at 1:00 PM, ADavidhazy wrote:
Trevor,
Reversal film processed to Dmax as an improvised IR transmitting,
light
blocking filter, should only be used in front of the camera lens.
It will
somewhat degrade the images as the film base is not optical quality.
On the other hand, a stack of deep Red and Blue filters will not
affect
image sharpness quite as much ... hardly at all in fact.
Placing a gelatin Wratten IR filter behind the mirror in a DSLR may be
asking for trouble. In a film camera a piece 24mm x 40mm or so
could be
taped (with very thin tape) across the image gate and between the film
plane rails of the camera. The filter material is so thin that the
rails
provide enough clearance so that the film does not touch the tape
or the
filter.
Contrast in an infrared image may be low for a variety of reasons.
Since
you are working digital an adjustment with levels might help.
Beyond that
curves I guess may help further.
Starting out with a knockout image, however, is the best way to go
IMO.
g'day!
andy
Before I bought my D200, I researched the IR possibilities and my
search
resulted in the only real negative of the D200 (IMO): really strong ir
blocking filter. Your Rebel took 30 sec for an exposure, eh? I
have an
IR filter that I could try with it. The last time I did, I got a
really
flat image. Where did you place the filter? I remember reading
your(?)
notes on using the e6 film for an IR filter, but i got the
impression the
filter was placed behind the lens. Just wondering how I could
adhere it
beneath my mirror without completely screwing up my gear. It'every
green
here in indonesia (a dramatic juxtaposition moving from egypt) and
I'd like
to find an alternative to buying a second dslr to send to the IR
doctor.
