From: Alan Friedman <alan@greatarrow.com>

Date: September 22, 2010 7:28:24 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Sun imaging


Hi Wolfgang,


I've never attempted to flat frame or dark frame for solar system imaging... I like to think of these as the curse of the deep sky imager. Any fixed anomalies on the chip generally disappear when the frames are aligned on the shifting details of the image in stacking.


Have you attempted to clean the dust off the cover of the CCD chip? I generally used compressed air, but I have cleaned the glass on occasion, very gently of course with a cotton swab.


best,

Alan




On Sep 22, 2010, at 7:57 AM, Wolfgang wrote:

Hello sun imagers,

my setup for sun imaging consists of a Baader energy reduction filter in front of the refractor followed by a 4X telecentric and finally a solar spectrum filter behind the focusser.
The camera in use with Astro IIDC Version 4.06 GM1 is a Point Grey Scorpion.
Being plagued by dust donuts on the camera's chip, I want to work with flats.
Unfortunately the advice offered by Astro IIDC's manual does not work.
I used 3 frames as proposed with the telescope not pointing to the sun but the results are no good.
The manual states:
"You should create flat frames by attaching the camera to your telescope or lens, then pointing it at about a 50% or so evenly illumination object and then taking an image."

However with the ERF plus the .5 Angstroem filter I do not know how to obtain correct illumination.
When imaging without the Ha filters, I normally use a flatframe-lightbox and have no problem to achieve the necessary adu's for the DSO-Camera , but I just cant figure out how to do it with the above mentioned equipment on the sun.

I hope that one of the sun buffs can advice a newbee.

Thanks in advance

Wolfgang