From: Alan Friedman <alan@greatarrow.com>
Date: September 26, 2005 10:02:55 AM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] M2 from Los Angeles - dew
When I shoot Mars I usually set-up the evening before to let my scope cool completely. I leave it with caps on covered by a tarp and go to sleep, setting the alarm to get up for mars (somewhere between 2:00 and 3:30 at the moment.) Things may have gotten dewy outside but the optics will be dry. If I am going to be up all night I always set up a Kendrick dew system. But for a couple of hours of imaging near dawn I wrap a layer of foam around my dewshield - this is will delay the formation of dew quite effectively.
Dew is a drag. It deposits airborne contaminants on the corrector which requires more frequent cleaning. I almost never use a hair dryer. Blasting warm air at the optics will generally ruin the figure of the glass for the balance of the observing session. At the end of the imaging session I cover the scope and put it away in the case (which has been left closed) and let the scope return to ambient temperature slowly.
Best -
Alan
On Sep 25, 2005, at 6:53 PM, Milton Aupperle wrote:
Hi Tim;
Very nice shot for a first time out doing DSO's with Astro IIDC.
I think you'll be impressed with the increased sensitivity your going
to get with Mars imaging, as the larger pixels give you about 40%
more light per pixel than the ApLux gathers. You can use less gain
and/or run at higher frame rates, which will help improve S/N.
I can sympathize with the dew problems. When I was on holidays I
tried imaging the day after it had finally stopped raining (3 days
worth). The scopes optics would "dew up" after 5 minutes and the only
way to briefly clean them was with the hair dryer at max. However to
make matter worse, when I checked the optics with a flash light for
how dewed they were, a bazillion little gnats and moths would land on
the optics and get stuck there. After 45 minutes of screwing around I
finally packed it in for the night. After another day of sunny
conditions all the dew was gone and the dessert like climate in
Saskatchewan allows me to image all night with none of those problems
at all.
TTYL..
Milton J. Aupperle
President
ASC - Aupperle Services and Contracting
Mac Software (Drivers, Components and Application) Specialist
#1005 - 815 14th Avenue. S.W.
Calgary Alberta Canada T2R0N5
1-(403)-229-9456
milton@outcastsoft.com
www.outcastsoft.com
On 25-Sep-05, at 10:17 AM, Tim wrote:
> Folks:
>
> I uploaded a file into the DSO area this morning. It's a stack of
> ten 20" exposures taken with
> my new Pt. Grey Flea camera (the camera is actuallly smaller than
> the Mogg 1 1/4" adapter
> with the 0.6 FR lens).
>
> I experimented for about 3 hours last night with various DSO
> objects. I would have shot Mars
> as well, but was set up in the back yard, and our house is 40'
> tall, so it didn't rise above the
> roof before I started to fade! Too bad, too. The seeing was
> pretty good, though the dew was
> moderate. I don't have a dew heater, so I had to use a blow dryer
> every 20 minutes or so. I
> thought the clouds would roll in by morning, but they didn't.
>
> Anyway, I am amazed at the quality of the images from the Flea.
> Dark frame subtraction in
> Astro IIDC works very well, too. If anything, I found that taking
> these sample DSO images
> with the flea was orders of magnitude easier than my "first night
> out" with my Meade DSI Pro.
> And the image quality is much better, too.
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