Re: [APML]: New photos

[Wil Milan <wmilan@airdigital.com>]

The Astro-Photography Mailing List
------------------------------------

Gene Horr wrote:
> 
> I have shot 2 rolls of RG25 through an E-210 for test purposes
> (in other works all of the photos look like cr*p <g>).  In a
> rural location sky glow started to become easily apparent after
> about 30-40 minutes.  Unless you are in *true* dark sky conditions
> I think that a 90 minute exposure will fry it.

Depends on where it's shot, I think. Last month I did some
testing with Royal Gold 25 on my astrophoto trip to the
Chiricahua Mountains in southeastern Arizona; under very dark
skies at 5200 feet exposures up to 40 minutes long at f/2.8 had a
black-black sky background, but the star fields were underexposed
by at least one stop. 

I was a bit surprised by the color balance of RG25; on those
underexposed shots there was more blue response than is usually
seen in astro films.

> > I've uploaded a larger version of the North American - Pelican
> > image. See
> 
> 
>http://www.airdigital.com/NGC7000_and_Pelican_Nebula_Tak_E130_Pro100_30m_Sunglow_Jun98_larger.jpg
> 
> VERY NICE!!!  I like how you were able to get a black background
> while still keeping fine detail in the nebulae.

No secret, just dark skies and a long exposure -- 30 minutes at
f/3.3 on Pro100 film. That's the equivalent of about a 2-hour
exposure with a typical SCT or refractor. From that same location
(the Sunglow Ranch in the Chiricahua Mountains) I also shot a
60-minute exposure with the same scope and film which *still* had
a black sky background. I thought that 60-minute shot (a very,
very long exposure at f/3.3) would certainly pick up some sky
fog, but now I'm thinking that when I go back later this month
I'm going to try a 90-minute exposures of M31 on Pro100.

The Sunglow Ranch is easily the finest astrophoto location I have
ever found. The skies are very, very dark, the seeing was
excellent in the week I was there, and the ranch manager was very
accomodating of my need to have a dark location. It's very nice
to be at a truly dark-sky location in the mountains, yet still be
only a few steps from a warm bed and a comfy room. I highly
recommend it for anyone who is thinking of visiting Arizona with
astronomy in mind. (The Sunglow Ranch has a web site:
http://soarizona.com/sunglow/).


Wil M.      
mailto:wmilan@airdigital.com
Astrophoto web site: http://www.airdigital.com/astrophoto.html
---
"When I consider your heavens, the work of your fingers, 
the moon and the stars which You have set in place, 
what is Man that you are mindful of him, 
or the son of Man that you care for him?"  -- Psalm 8