Re: [APML] anti-pollution dark red filter

[Radu Corlan <rcorlan@pcnet.ro>]

The Lumicon 'H-alpha' filters are similar to W92 - and on glass.

Radu

On Mon, 17 Feb 2003, Nicola Montecchiari wrote:

> Jose,
> 
> I wanted to buy an W92-like filter but I cannot find it on glass :-(
> otherwise I would have been buying it.
> 
> Nicola
> 
> ----- Original Message -----
> From: "Jose I. Alarcon" <JIALARCON@telefonica.net>
> To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
> Sent: Monday, February 17, 2003 9:47 PM
> Subject: Re: [APML] anti-pollution dark red filter
> 
> 
> > 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
> > >
> > >
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> >
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-- 

The future isn't what it used to be. 

-------------
Radu Corlan           Snail Mail: Bucuresti sect. 1, 
rcorlan@pcnet.ro             str. Argentina nr. 28, 71206 Romania

   You can still escape the "Gates" of Hell!   
                 Use Linux!                       


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