Re: [APML] IC1396 in Ha /Tech Pan

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

Scott,
    Looking pretty good for your second tech pan image! It looks like your
lens has a "hot spot", probably exaggerated by the light pollution you are
shooting through. The bright patch just to the right of 1396 shouldn't be
there. You might have to do some Photoshop jiggery pokery on your images
from town to reduce this. For comparison, have a peek at
http://members.shaw.ca/astrophoto/files/ic1396bw.jpg done with a 180mm f2.8,
H-alpha and 60 minutes. It was shot from a mountain top 10 hours west of
here back in 1991, it does not have the brightening your image does.
    Exposure time varies so much, depending on sky brightness, how effective
the hyper is, development time, etc. I haven't shot through a
telephoto/H-alpha combo for a while, but have been meaning to. I would
probably start at 2 hours @f2.8, possibly 3. With my Schmidt @ f1.5 and a
W92, I usually go for 45 minutes. But this is under good skies, as long as
the aurora isn't active. If your scanner can't pull out an image, then you
have probably gone too long. :-) It's hard to tell from this end if you can
shoot longer. The background density caused by light pollution will be your
limit. If the background is pretty thin, then shoot longer. If you have to
hold it up to a mag -26 light source to see anything, then back it off a
bit.

John Mirtle
Calgary, Ab. Canada
http://members.shaw.ca/jmirtle

----- Original Message ----- 
From: "Scott Hammonds" <shammonds@creatorsview.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Wednesday, September 24, 2003 2:20 PM
Subject: [APML] IC1396 in Ha /Tech Pan


Hi List,
This is my second reasonably successful Tech Pan image. I am still
experimenting with processing these black and white images and I would
appreciate comments and criticisms.
I managed to get 2 shots last night before I needed sleep after
returning from the Braves game, I'll try and post the other one later.
http://www.creatorsview.com/pages/techpan.html

Based on what you see from my images, do you think I should expose
longer than the 50 minutes I have been using so far? Those of you
shooting tech pan please let me know what you are using for exposure
lengths.

Thanks,



Scott Hammonds



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