Re: IE yellow/oranges (was: IR- screw Leica rangefinder option? Don'

[boblong@xxxxxxxxxxx (Robert Long)]

On Tue, 27 Aug 1996 20:52:33 +0100, you wrote:

|Yep, you are right about the steep cut off compared to #8 and #9.
|But even besides that, both #8 and #9 are roughly 20nm more 
|transmissive towards the blue, it's not just the steepness of the plot.

The includsion of the bluer light is what "muddies" the images, I
suspect, while the lack of the wavelengths just above 500 nm is what
leaves part of the dye spectrum untriggered and give an "incomplete"
look to the spectrum of the resulting slides.  Any of these
"abberations" could be used for expressive purposes, of course, and in
recommending the Wratten 12 Kodak is surely thinking of technological
uses, rather than expressive ones.  But as I say, the clean, bright,
perky color that results is what I'm going for with that film anyway.

|Another interesting difference, at least according to my 1928
|Wratten catalogue: #12 also shows a 2-3% transmissive 'dip',
|centering around 310nm. Not much, but apart from #15, none of the
|other yellow/orange colors shows this dip.

Yes, I've noticed that many times before and always wondered at it.
But the band is narrow enough and shallow enough that it should have
little effect on the results.

BL

------------------------------

Topic No. 16