From: Milton Aupperle <milton@outcastsoft.com>
Date: June 9, 2012 11:08:17 AM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Re: VT and USB 3
Hi Stephen;
Very nice set of images:
and I'm glad it worked well for you stacking wise.
A question for you Visible Light solar imagers. I was testing out my old MAK 5" scope with a Solar Filter (Kendricks Baader Photographic model) mounted in front before VT. The filter is about 5 years old and I haven't used it in several years. It's sat in the original box on the shelf. I have use dit in the past for solar imaging and frankly, had forgotten how much fun the small 5" and solar imaging is.
I was shooting at 1510 mm focal length with the Grasshopper 2 camera (0.35 ms exposures) and a Red Astrodon filter (which has UV and IR Block coating). The sky was crystal clear with no clouds interfering. To get the full sun, I needed to shoot 6 movies and then after stacking, I tried compositing them into a single seamless image. The issue is that the images vary erratically in brightness across the images - and compositing seamlessly doesn't work. I have done this for the Moon and DSO targets countless times and never seen anything like this.
I also tried shooting flat frames of the sky 40° away from the Sun using 1 second exposures and moderate gains and flat correcting a second set of movies I took, but I still get significant variations from the resulting stacks.
So I'm guessing the the filter is the root cause. Is that normal or do I just have a bad / deteriorating filter? Or is that why people are buying the large format cameras for solar imaging to avoid this?
Thanks in advance..
Milton Aupperle
On 2012-06-09, at 10:04 AM, Stephen W. Ramsden wrote:
of anyone is interested My PGR ASTRO IIDC shots of the Venus transit from
the Keck telescope are up at
Thanks for a great product Milton. I shot 200 frame .movs on a manual backpack mount in 30mph winds on the side of a volcano and the software stacked all 300 movs without coughing..
On Jun 9, 2012, at 11:20 AM, Milton Aupperle <milton@outcastsoft.com> wrote: