From: Milton Aupperle <milton@outcastsoft.com>
Date: June 8, 2007 11:09:13 AM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] For your viewing pleasure
Hi Jim;
On 8-Jun-07, at 10:35 AM, jimchung2338 wrote:
Hi all,
I've come to the conclusion that at low altitudes, Jupiter is best imaged at short focal lengths
due to limited seeing and faster fps shooting.
http://tech.groups.yahoo.com/group/Astro_IIDC/files/Planetary/JupiterJune7w4moon.jpg
I tried Jupiter one night under low turbulence skies and have basically got nothing but a muddy mess. It's only 16° above the horizon here, so the chances of doing any high res Jupiter images are pretty well zero.
Milton also inspired me to try a shot at Venus using a Baeder UV filter, I'm not sure if I see
any clouds either.
Venus is a tough object to image, as we are both finding out.
My biggest issue is getting sharp focus because of turbulence at that time of day here. And as you said for Jupiter, going to 2x barlow doesn't work for me as I need to increase gains a lot and also increase exposure time too, so the faint features I'm looking for get lost in the noise and smeared in turbulence. So I'm shooting prime focus at 30 fps and then scale up 2x when stacking.
Was your Venus shot taken using the Flea Mono camera in 8 bit or 16 (12 actual) bit depths?
With 8 bit using the TIS DMK21Af0.AS Mono camera, I'm getting some banding if I push the processing too hard because it only has a total 8 bit / 256 shade range. So you have to be very careful with your exposure and gains so that you don't over or under saturate the image. The detectable stuff is near the terminator and I'm winding up with only having a narrow range of pixel values of maybe 30 to 60 out of 255 for features in this area. I think a higher bit range would work better and allow one to tease out more details.
And because of obstructions (i.e. over hanging balcony and south building wall) where my scope sits I have a 58 minute observing window for venus and I have to shooting in very bright twilight between 9 and 10 pm. I'm putting together a little collage of venus shots, but so far I'm chasing "shadows" as far as possible features go.
Thanks for sharing..
Milton J. Aupperle
President
ASC - Aupperle Services and Contracting
Mac Software (Drivers, Components and Application) Specialist
#1005 - 815 14th Avenue. S.W.
Calgary Alberta T2R0N5
1-(403)-229-9456
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