Re: [APML] The Glory of Rho

["Chris Cook" <chris@cookphoto.com>]

Hi Wade,

45N will be tough but your site looks to be inky black.  If you get a good
night with excellent trans, you should be able to pull it off, no problem.
Your exposures at f/4 sound correct.

Btw, I darkened the Rho shot just a hair.  Hit reload and take a look.  It
was so slight though, it may not be that noticeable on other monitors
without a side by side comparison.

http://www.abmedia.com/astro/current/Rho-Region.html

Chris

-----------------------------
Chris Cook Photography
www.cookphoto.com


----- Original Message ----- 
From: "Thomas W. Earle" <twade@bmi.net>
To: "'Discussion of Film Astrophotography'" <astro-photo@seds.org>
Sent: Saturday, June 18, 2005 4:55 PM
Subject: RE: [APML] The Glory of Rho


> Chris,
>
> Yet, another excellent image from your trip to NM.
>
> I hope to capture Rho with my Pentax 300mm EDIF F/4.0 lens this
> upcoming New Moon.  I'll be using E200 too since it surprisingly
> recorded the blue spectrum quite nicely under your very dark sky.
> It's definitely a challenge capturing these southern objects from
> 45N.  We only have 3-3.5 hours of total darkness this time of year.
> I feel for those that are even farther north.  Despite having some
> of the darkest skies in the continental US, Mother Nature doesn't
> allow many "cloud free" opportunities this far north, especially
> during New Moon.  Just this past New Moon, I sure was wishing I
> still lived in West Texas.  The Water Vapor was red the entire New
> Moon window which means excellent transparency.  I had to battle
> high clouds the whole time.  I did try capturing Rho with Provia
> 100F pushed 1 stop.  I exposed it for 75 minutes.  I initially was
> going to go for 90 minutes but I knew I didn't have good enough
> polar alignment judging from the corrections the STV was making.
> Albeit, I'm not certain if it was poor polar alignment or the gusty
> wind causing the corrections.  It was a bad night anyway with 15-25
> mph winds and patchy cirrus.  I'll get them developed this upcoming
> week.  If I have any images worth publishing, they'll be ready for
> viewing late July.
>
> It still floors me that you are able to expose for 40 minutes at
> F/2.8.  Using Michael Covington's Astrophotography Calculator, it
> shows the maximum exposure (i.e. sky fog limit) for your setup is 45
> minutes.  Since I'll be shooting at F/4 and pushing E200 a full stop
> I figure my limit is probably around 75 minutes.  As a result, I'll
> take two shots of Rho Ophiuchi: one 60 minute and one 75 minute.
>
> Again, thanks for sharing your excellent images over the past week.
>
> Wade
>
>
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