From: Milton Aupperle <milton@outcastsoft.com>

Date: November 23, 2009 9:43:08 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: proper darks and flats -- somewhat long

Hi willie;

On 23-Nov-09, at 12:10 AM, Willie Strickland wrote:

I started writing this the other day, but didnt get it finished till tonight.  My apologies ahead of time for the long-winded nature of the post.  I hope it makes sense and isnt too labored.

Thanks for the discussion Milton.  I remember the thread about your analysis of the problem.

I like the your idea of the ability to save master darks of different exposures and master flats for each filter set and then just choose whichever you want to use for processing during capture.  I also wish I could view the darks and flats that I take with AstroIIDC so that I can make an evaluation of their quality before using them for capture.

Why not just create the Flats or Darks as an Average Frame and then you can open the resulting tiff and look at it?

-------------Snipped for Brevity-------------

I have created a series of master darks for each camera and name them with the exp time as well as the air temp at which they were taken since none of my personal cameras are cooled.  So I have dark30s50df, dark5m30df, etc in separate folders for each camera.  I decided to label the air temp so I could later compare different dark masters at different temps to see how they vary.

The TIS camera (or any camera for that matter) have to come to equilibrium temperature if that's going to work reliably. You should be running the camera for around 15 to 30 minutes at at least 15 fps to bring it up to temp before shooting your darks or images. You might want to try using a cheap outdoor digital thermometer with the sensor on a wire / cable to monitor the outside case of the TIS camera to see what temperature it stabilizes at. They do put out quite a bit of heat.

I am not having as much success with flats, hence my question.

What specific problem are you having with Flats and how are you taking them? It should not be any more complicated than dark frames with Astro IIDC. The main thing to remember with Flats is you have to be in focus if you want them to remove dust donuts and other small particulate matter. With Darks your measuring the CCD's response to exposures time, with Flats your correcting the optical path and focus is part of it.

I always post process my my movies using the Average Flat Frame I captured and never do live flats.

And I havent done much processing of movies either.  Since getting my DMK, I have captured a lot of movies that I havent had time to process yet.  I have put in 6 or so hours today on processing, most of that reading the manual and trying different settings on the same original.

You cans save a lot of time in experimenting by creating a "Reference Movie" (see page 39 of the Astro IIDC manual) which has only the sharpest frames in it. Then on the next and subsequent tests your only selecting the reference movie which has a small number of frames and therefore takes less time to process.

HTH..

Milton Aupperle