Re: [APML] Sky Pollution Astrophotography - on film

["John C. Mirtle" <spampit@shaw.ca>]

Nicely done Bill!
    It really is amazing how well the Lumicon H-alpha or W92 cut through the
crud with either tech pan or E200. I used to shoot from in town as well,
back in the mid 80's under mag 4 skies. Back then I used to focus with a
Deep SkyŽ filter and then swap in the H-alpha. That is how I got my first
shot of the cone nebula! At f4.5 I found the exposure times reasonable even
using tech pan. These filters also work well with moonlight, as you can see
with http://members.shaw.ca/jmirtle/gammacyg.htm . The last quarter moon was
up for that shot. If you want to shoot larger planetaries, a UHC filter
works well too.
    You are showing a bit of vignetting. If you could reduce that, you
should be able to tease out a bit more "stuff" from the image. Nice to see
some tech pan images!

John Mirtle
Calgary, Ab. Canada

----- Original Message -----
From: "William R. Mattil" <wrmattil@ix.netcom.com>
To: <astro-photo@seds.org>
Sent: Sunday, November 30, 2003 3:24 PM
Subject: [APML] Sky Pollution Astrophotography - on film


> Gentlemen,
>
> I spent a bit of time cobbling together using surplus 48mm filter
> casings and some wratten filters (#92 and #2B) a deep sky nebula filter.
> The idea was to use the #2B to focus through and then replace it with
> the #92. I mean this works for Schmidt Cameras so it should work at F/4
> right ? This resultant filter attaches to the Lumicon "T" ring after the
> OAG prism So the ST-4 doesn't have to deal with it :^). I thought that
> this would be useful for doing testing from my extremely light polluted
> backyard and ironing out system problems so that trips to a dark sky
> aren't wasted. To be honest though I was a bit surprised at the results,
> after ironing out a proceedural issue with the knife edge focuser
> (Thanks Jerry !) The results are far better than I ever hoped for.
>
>
> http://www.celestial-images.com/B33.html
>
>
> This is a full frame scan. No cropping and very slight curve adjustment.
> Specifics are as follows:
>
> 45 minute exposure on hypered Tech Pan using a 253mm f/4 with Lumicon
> OAG and coma corrector. Guided with the ubiquitious ST-4. Some
> vignetting is apparent and its not too difficult to see where the shadow
> of the pick-off prism is :^) I probably should modify the Nikon F with
> some tape to take up some of the extra slop when using Tech Pan and a
> dry air purge wouldn't hurt either but comments would be most welcome
> including any Photoshop processing tips.
>
> I shot a total of three of these, 45 min, 30 min and 20 min. And may try
> stacking them.
>
> Regards
>
> Bill
>
> --
> William R. Mattil |
> wrmattil@ix.netcom.com | http://celestial-images.com
> (972) 399-4106 |

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