Deepskystacker Settings

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Comment by Al McAdam on June 2, 2011 at 4:31pm

I am looking at a Sony @550, this camera has a CMOS sensor as opposed to CCD, any comments please Thanks Al

Comment by Al McAdam on April 28, 2011 at 6:44pm

Thanks Russ, I figured with my luck I could waste the whole rainy afternoon and maybe I did but at least I had something to do. I saved 20 shots at 70°F and a similar number with everything the same at 55°. I was reading in Michael Covington's book on DSLR Astro that there is about a 8°F span but I will try to stick with the 5° range you suggested. I just found his quote,"Theoretically,the dark current of a silicon sensor doubles for every 8°C (15°F) rise in temperature." Therefore I think your 5°F range is a good one.
I may have lucked out on the focus because I haven't taken any other pictures since the last time so my camera focus should have still been decent unless there was a temperature adjustment.

Comment by Russ Ruggles on April 28, 2011 at 2:30pm

One would assume you could return close to the same focus as before but for taking flats what is it you'd be focusing on? For your lights you focus on a star. If you remove the camera and/or change the focus you have to wait for another star to focus again - then it's too dark to take flats. My thoughts are if the focus has changed then the diameter of the dust motes have also changed as well and any other optical defect so your flats will not work as good as they could or should. What I've done in the past is on my portable system - I pick the whole thing p and carry it in the house or garage for the night. Then the next day I drag it back out a take my flats. On my pier mounted system I just shut down and cover it up for the night. If you have a small enough OTA you could use the white screen of a laptop in a pinch or make a lightbox from the many plans online and then take your flats right before to break down for the night.

Comment by Al McAdam on April 27, 2011 at 11:14am

In regards to my library of Darks, Dark Flats and Bias files, maybe Marc or Russ can answer this because I read somewhere "at the same focus as your lights". As Marc mentioned if you move the camera you can use photoshop to get rid of the dust mites so I have marked the camera position and my question is,"Am I OK with the focus bit?"

Comment by Marc Basti on April 26, 2011 at 7:15pm

Al, I like it. You tend to get pretty resourceful (and get weird looks) when taking darks. Marc

Comment by Al McAdam on April 26, 2011 at 6:25pm

Russ, I started my collection at 55°F with 20 Darks at 1600 and 30" and then I took 20 Bias also at 1600 and 1/4000th same temp. It was raining a bit so I followed your procedure except I put the camera in the BBQ for protection and acclimatization. I can do the cold one in the fridge later as the battery is low

Comment by Al McAdam on April 25, 2011 at 7:30pm

Thanks Russ that is a great idea, I will wait until my wife is not around. During the winter I had a bag with a heating pad plugged into my extension cord and it solved the problem of the little AAA batteries in the timer from getting cold and now the whole process is reversed as the timer will be outside the fridge. The big surprise will be for the camera it thought summer was coming.

Comment by Russ Ruggles on April 25, 2011 at 6:56pm

Hey Al, what better time to catch some dark frames than on a rainy day/night. Here's a trick or two you can try. Get yourself a good thermometer and check the temp in your refrigerator. Place your camera in a ziploc w/o battery and place it in the fridge for an hour. Take out and place battery back in - set up your timer to take your duration, set ISO and then place it back in the fridge. The camera will warm up after the first couple of shots and then the rest should be pretty even in temp. Then do the same thing out in your garage or any other place it gets cool. Over several days, weeks or months you can build a dark library. The thermometer is so you have an idea where the temp is when you start. The data in the images should tell you the temp of the sensor - if you have a camera that records that. I use BarkyardEOS for Frame/focus and Capture which records all of this data. The bad thing - a cable running out of the fridge,,, oh and trying to explain it to the wife LOL

Comment by Al McAdam on April 25, 2011 at 5:22pm

Marc I did read the DSS info on flats and darks and Dark flats plus other sources, it made for an interesting afternoon since it was raining anyhow.

Comment by Al McAdam on April 25, 2011 at 5:20pm

Thanks Marc and Russ apparently we are not supposed to have good weather until Saturday but if we have some breaks I may be able to get out during the day and catch a range of temperatures as Marc suggested to make a library.

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