Infrared Help Please (2 pics with 5700)

Started Jul 12, 2004 | Discussions thread
_Kamran_ Senior Member • Posts: 1,773
Thank you ookpik for the accurate info! nt

ookpik wrote:
Kamran,

Curiosity got the better of me, so I e-mailed H&H. According to
one of them, Will Harrison,
"89-B: Absorbs visual below 670mu (Passes 30mu of visual)
"88-A: Absorbs energy below 710mu (Cuts all visual + 10mu of the
near IR equal to the R72)
"87: Absorbs energy below 730mu (Cuts all visual +30mu of the near
IR)"
Not sure of the units used by Will, but there appears to be a "50
nm window" between H&H's 89b and Hoya's R72. That would make the
R72 more of a "true" IR filter but, as your photographs show, the
89b may be more suitable.

ookpik

Kamran wrote:

ookpik wrote:

Is it possible that all "89b" filters are not created equal? Which reminds > me, where did you get your 89b filter?

I guess it's very much possible. I bought mine from Harrisson &
Harrison. The build quality of the filter is not as good as that of
Hoya, but still works for me. They manufacture filters in their own
lab (sounds a small company). Therefore it's possible that it's not
actually 89b (They called it 89b so I call it).

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Kamran
http://www.pbase.com/kmahbub
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