Re: [APML] anti-pollution dark red filter

["Jose I. Alarcon" <JIALARCON@telefonica.net>]

Nicola, I found the B+W 091 filter rather disappointing from my poluted
site.
It is a "Wratten 29". I should have bought instead a "Wratten 92" which has
a higher
cut off frequency.
Regards

Jose I. Alarcon

----- Original Message -----
From: "Nicola" <nmontec@libero.it>
To: "APML" <astro-photo@seds.org>
Sent: Monday, February 17, 2003 2:48 PM
Subject: [APML] anti-pollution dark red filter


> Dear All,
>
> I'm going to buy soon a dark red filter B+W 091 for my 200mm tele.
> I read on Reeves' book that it is a nice idea do keep the filter on for
half the
> exposure time and than unscrewing it to get a normal colour for the
background.
> I was wondering if any of you tried to shoot two pictures, one with a red
filter
> for all the exposure until skyfog and another one immediately after with
no
> filter exposed for less then the skyfog time; after that, replacing the
red
> channel of the second photo with the one from the first picture.
> Does it make any sense? Would I get better nebulas?
>
> Cheers
> Nicola
>
>
> _______________________________________________
> Astro-Photo mailing list
> Astro-Photo@seds.org
> http://seds.org/mailman/listinfo/astro-photo

_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo