Re: [APML]to IR cutoff or not to IR cutoff...

["joe" <jmize@svic.net>]

... any ideas where one can find something like this?

http://www.astrovid.com/schuler_astro_imaging_filters.htm
About half way down the page is a list of Schott glass composite filters
with extended R & IR filters...joe  :)


"May You Go Among The Imperishable Stars"

Joe Mize:         http://www.svic.net/jmize
Chiefland, FL    29:24'33.4"N    82:51'37.7"W
Moon Phase:     http://tycho.usno.navy.mil/cgi-bin/phase.gif

----- Original Message ----- 
From: "Chuck Vaughn" <aa6g@aa6g.org>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Sunday, July 06, 2003 2:49 PM
Subject: Re: [APML]to IR cutoff or not to IR cutoff...


> Tony,
>
> > That's a great idea ... sort of an "extended" red... but I wonder
> > if it wouldn't overpower the rest of the colors... there would be so
> > much "red" that it might overpower the remaining colors in the image.
> > It might shift our perception of the image
>
> You'd need to reduce the exposure time for red compared to green and
> blue because the total bandpass would be greater than before. This is
> no different than the blue filter I use with TP that goes out to 350nm.
> Everything short of 450nm is simply blue. On the long side, anything
> long of 650nm would be completely red.
>
> >  ... any ideas where one can find something like this?
>
> I don't know what size filters you're using. If it's non-standard, you
> could have a larger filter cut down.
>
> Chuck
>
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