Re: OR: Sketching at Coyote Lake, 09/04/2004

From: Alexander Avtanski ^lt;avtanski_at_No-Spam>
Date: Tue Sep 07 2004 - 10:35:57 MST

Hi Alvin,

I'm glad you liked the sketches. Sketching proved quite simpler than
I expected and didn't take much time. I used PhotoShop to process
the rough sketches made in the field and frankly was surprised by the
results...

Thanks for the kind words,

- Alex

P.S. Another TAC member asked me for more details about the image
       processing - since I already sent him the detailed instructions,
       I'll just copy and paste those below, in case you find them
       interesting. Here is that message:

-----------------------------------------------------------------------
Regarding the technique I use - it is still "under development", but
generally this is what I do:

At the scope I make a sketch in my notebook - I use regular pencil and
sketch on my notebook paper (which is nothing special, and even has
lines for writing on it). I also make a detailed description of what
I see at the eyepiece - just in case I need it later.

When I get home I scan the picture from my notebook. Using PhotoShop
I overlay it with a half-transparent black layer and with the "airbrush"
tool start painting white over the dark areas (the penciled ones) in
this half-transparent layer until there are no lighter and darker areas
anymore. This may sound a bit complicated - that's because I can't
explain it very well, - basically what I'm doing is from the penciled
"negative" I make a manual "positive" image - I do this manually,
because this way I have much better control and reduce all the defects
(like areas that have been erased from the original and I now know that
I shouldn't pay attention to them, places where the pencil broke, etc.)
When I turn off the scanned layer the "positive" image shows up and
looks exactly as I remember it in the eyepiece. If something does not
look like on the paper sketch, now I fix it - again manually. Finally,
in a separate layer I add the "stars" - again showing the scanned image
through a half-transparent layer. Putting the stars in separate layer
allows me to independently adjust the brightness of the nebula and the
stars until I get the correct balance.

I hope to improve this technique in the future - looking at the final
images I see some things I don't like (the stars are too fat, I didn't
sketch enough stars in all the FOV, etc.).
Received on Tue Sep 7 10:37:29 2004


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