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Posts Made By: David Albert

October 2, 2003 08:11 PM Forum: Lost Contacts and Personal Messages

Looking for waltdben

Posted By David Albert

I am looking for the individual that started the Yahoo group ci700_users. The group is being flooded by pornographic postings and waltdben is listed as the only moderator. His e-mail address in invalid and we need him to appoint another as the moderator.

September 4, 2004 02:40 PM Forum: CCD Imaging and Processing/Solar System

What is this

Posted By David Albert

The best way to correct vignetting is with flat frames. They have the added benefit of correcting any shadows from dust on any of the optical surfaces. All you need is a few images (it is best get an average of a few) taken of an evenly illuminated surface. Don't change the focus or position of the camera. A shot of the twilight sky with t-shirt or towel stretched over the end of the OTA is a quick and dirty way to take a flat frame. Adjust the exposure to get a peak value of 35 to 50% of saturation. Any ccd software can make the correction to your image once you obtain the flats.
Dave

December 14, 2005 01:00 PM Forum: Home Observatories

Observatory Teething Problems

Posted By David Albert

Regarding the corrector fogging - you definitely need to use a dew shield in combination with a heater. I use a Dew Buster heater controller and they state that use of a dew shield is mandatory for good results.
I made my own dew shield using a sheet of "refletix" (not sure of the spelling) insulation which is like heavy duty bubble pack sheeting that has a shiny silver coating on both sides. I got mine at Home Depot. On the inside is black felt attached with spray adhesive.
Anacortes sells one made from this material from Just-Cheney Ent. I didn't see one specifically for the 16" SCT, but they could probably make one for you if you don't want to do it yourself.
I use mine with the Dew Buster on a 8" SCT in the Seattle area which is notoriously damp and it works great.
Dave