Re: hoya R72 Filter

["joe b." <joe-b@xxxxxxxxxxxx>]

In message <199608202340.AAA24091@xxxxxxxxxx>, Willem-Jan Markerink
<w.j.markerink@xxxxx> writes
>The Hoya R72 is definately *not* visually opaque. 
>It equals a Wratten #89B. Even the much darker 88A can be looked 
>through with some effort.
>This 89B color is also known as Schott RG695, which is used as normal 
>IR filter for both Heliopan, B+W (092) and Rollei.

There seems to be a slight difference when I compare directly between a
couple of these that I have. Holding them in front of one eye just now,
through the B+W 092 I can clearly see the light bulb above me and I can
also the detail of the moulding on the ceiling around the light fairly
clearly. When I try this with the Hoya R72 I can see the lightbulb, but
to see the moulding takes some effort. It is visible, but only just. I
wonder whether this is just variation between samples, or whether the
Hoya R72 is actually a (slightly) different filter. I have known a B+W
filter to have the wrong glass in the mount- ie not what it says on the
filter rim, but a closely related filter instead; only once though, but
it shows it can happen. But this 092 is definitely  a real 092, as it is
the same as a couple of 092 filters I've got in other sizes.
-- 
joe b.

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Topic No. 26