Re: Infrared sensitivity of Silicon PhotoDiodes

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

On  7 Jan 98 at 9:35, Thomas H. Hogan wrote:

> Dear Elton  - Infrared light doesn't pack the punch that
> visible and ultraviolet light do.  Just make sure that you
> are not reading ultraviolet light because the 87 filter 
> transmits ultraviolet.  Most meters would
> sense ultraviolet but cannot sense infrared.

None of the red filters transmits UV, including the opaque ones.
I think you are confused with the UV-pass filters, those transmit IR, 
and require an IR-block filter in case of HIE, to make sure only UV 
makes it to the film. 
A totally opposite filter was recently launched last PhotoKina by
B+W: a 'digital' filter, for video cameras (and CCD still's?),
blocking both UV and IR....before you had to use two filters to get
this result.

For exact data on filter transmissions see the URL in the footer 
below.
 

- -- 
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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