Re: HIE in Hasselblad

[PeteScherm@xxxxxxx]

Charles,

I think you are making more of my skills than I possess.  Remember, I was an 
engineer in an earlier configuration and we tend to do things a bit 
compulsively.  The two lines (unnecessary, I'm sure) are a result of my 
having marked the lenses when I only owned the R72 filter which, I believe, 
has some sort of a 50% transmission at 720 nm.  I could look it up, but the 
numbers aren't too important as relates to my obsessive/compulsive 
personality (as you may recall, I'm also the one who has all of the map 
co-ordinates of Simon Marsden's photo locations in his "In Ruins" book).

Anyway, I later bought a #87 filter (870 nm?), looked it up, and decided to 
put another little red enamel dot on all of my lenses.  But I don't think 
that it matters  too much.  But I have kept a mental note of one item that I 
saw in this list about the refractive characteristics, etc. of IR and it was 
recommended that stopping all of the way down (f/22 with my shorter lenses, 
f/45 for the 250) was not the best idea for maximum sharpness, so I have 
unilaterally limited my minimum apertures to 16 and 32, respectively, when 
shooting IR.  Perhaps the person who wrote that refraction stuff originally 
might care to comment.  I don't have a record of it, for some reason.

Pete Schermerhorn, in the glorious Berkshire hills of western Massachusetts
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