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Re: [ATM] Wratten #3N5 filter responses

On Mon, 11 Jun 2007, hermit wrote:

> Dominic-Luc Webb wrote:
> > It is known that the 3N5 is used in B&W photography. It is in
> > fact one of the more popular filters for B&W.
> >
> >
> The neutral density part makes it much more limited for astronomy
> though.  In B&W photography yellow is used in landscapes and helps
> darken the sky some.  Not as important with some of todays emulsions.
>
> Ken Lowther


Agreed. As for Moon viewing, I would need to think on a good reason
to use a yellow filter. I guess the sky would indeed be darkened,
but I would be concerned about deterioration in the lunar image. I
presume the exposure time would need to be increased for photography,
and tracking might be an issue. Admittedly, I have mainly used
narrow pass photometry filters, never giving much consideration to
image quality (used a PMT with no image).

Dominic-Luc Webb

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