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Re: [APML] M31 filter?
This time of year M31 should be pretty much straight up. I'm a 4000' with
pretty dark skies. The only problem might be smoke from range fires in central
Oregon. Think I'll try 30, 60 and 90 minutes.
Then there's The Veil......
Philip Perkins wrote:
> Greg,
>
> Roland's suggestion is the way to go. I don't think filtering would be
> very effective at reducing the core because M31 is all broadband light and
> the colour difference in the core is due to a bias towards the red part of
> the spectrum, but there is still plenty of light in the remainder of the
> spectrum. As for exposure times, I have no experience of tech pan, but if
> I was exposing hypered colour film using similar instrument and camera to
> yours, I would expose between 70 and 90 minutes depending on the darkness
> of your sky and the elevation of the object above the horizon.
>
> --Philip
>
> At 11:30 20/07/02 -0700, you wrote:
> >Suggestions on exposure times?
> >I've never used Hypered Tech Pan before.
> >AP 6" f7.5
> >Pentax 6x7 and 4" FF
> >
> >Chris1011@aol.com wrote:
> >>In a message dated 7/20/2002 1:12:27 PM Central Daylight Time,
> >>mueller@silverlink.net writes:
> >>
> >>
> >>>Since the inner core of M31 is different color (wavelength)
> >>>than the fringes, does someone know of a filter that would effectively
> >>>filter out the over powering core, but allow the fringes to come
> >>>through. Needles to say I have enough core luminance, but I'd like to
> >>>boost those hard to pull out blue edges
> >>
> >>I would take two images, one shorter exposure that brings out the core
> >>detail infull, and one very long exposure that burns out the core but
> >>shows the outer regions. Then layer the properly exposed core over the
> >>burned out one using Layers in Photoshop.
> >>
> >>Roland Christen
>
> Philip Perkins - philip@astrocruise.com
> Wiltshire UK & Luberon France
> Astrocruise - http://www.astrocruise.com
>
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--
==
Greg Mueller Port Gamble, Washington
Amateur Astronomer, Machinist, Filmnut
Tech Tools and Astronomer's Gizmos
http://www.muellersatomics.com/
Homepage
http://users.silverlink.net/~mueller/
==
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