Re: Flash and IR filters and Konica 750

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 27 Jan 98 at 17:27, George L Smyth wrote:

> Willem-Jan Markerink wrote:
> > 
> > Mmm....AFAIK, Hoya does/did not have a #87, only a #89B ("R72", very
> > dark red, but not opaque)
> 
> It's as close as you can get.  The "72" in the "R72" references the fact that it
> cuts at 720nm.  Excellent filter.

I have one of those, and it is definately #89B, not #87.
One can look through #89B, but not through #87.
The R72/720nm refers to the specification for 50% transmission, like
with most filters. For #87 this spec is at 795nm.... 

You most likely confuse the 0% mark of #87 (740nm) with the 50% mark 
of R72 (720nm)....


- -- 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
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