What am I doing wrong?! Help much needed

[nmoushon]

So I got my first CCD camera over the weekend - a second hand SBIG 2000XM - I downloaded all the drivers and got it to respond to the program CCDOps (which is SBIGs capturing software). It is a self guiding CCD, which has a second chip that guides while the first captures images. I tried getting it to hook up to PHD but couldnt so gave up on that and focused solely on at least getting an image out of the clear night. I quickly switched to my finder guider and got that hooked up and running.  I got it to its set cooling point at -10C and started taking my first 300sec sub on my CCD. The first attached image is what the CCDOps screen showed at the capture. A blown out M31. I thought maybe its just way over processed to show what your capturing. And the the second attached images is what I got after a very short stretch in PS! I have never seen anything like this before. Even reading all the CCD problems from other on the forum...none where like this. I hope I'm doing some newbie mistake and that I didn't buy a bad second hand camera. Can anyone point me in the right direction?

[Oddsocks]

Difficult to be sure as the image compression used in the conversion to PNG for the web upload creates artefacts of its own but the granulation looks like condensation/ice on the sensor.

This is not so unusual for a camera that is a few years old, the desiccant plug in the body of the camera needs to be re-charged in an oven at least once a year and possibly more often if moisture has built up over some time.

The instructions for re-charging the desiccant plug are copied below from the SBIG manual.

When you cool the camera don't cool to -10deg, or whatever you decide to set, in one go, cool in no more than 10 degree steps and allow the camera temperature to stabilise for at least 5 minutes between each step, this will help to avoid condensation or ice forming on the sensor.

Don't forget to take dark and bias frames as well as light frames, modern cameras are quite good at controlling and suppressing random and read-out noise but older cameras from only five or ten years ago do need to have proper calibration frames taken and applied to the light frames to correct the image, for some reason it is a common perception that cooled cameras are easier to image with than DSLR's but this is far from the truth, cooled CCD cameras need quite a bit of work to produce good images.

Test the camera with darks, set -10 deg, cover the camera window and take a 300 second exposure then look at the image, if condensation/ice was the cause then the granulation in the image should not be visible, only bias/read-out noise and hot/cold pixels should be seen, try also taking a dark-bias frame, minimum exposure time set and covered camera window, this image should only have read out noise present and no structure.

There are quite a few settings to be made to the SBIG CCDops software so that you see the image with the correct screen stretch and also when saving the image for later PS processing but I don't use this software so won't give you specific advice other than to download the CCDops manual and have a good read through a few times, the histogram tool is especially useful when finding the correct exposure times for lights and flats.

Link to the camera manual if you don't have a copy:

http://www.sbig.com/site/assets/files/18223/usbmanrev14.pdf

Link to the CCDops manual V4.0:

https://www.sbig.com/site/assets/files/18240/opsman4.pdf

Link to the CCDops manual V3.5:

http://www.sbig.com/site/assets/files/18239/opsman3.pdf

Instruction for recharging the desiccant plug:

B.2. Regenerating the Desiccant

This section describes the regeneration procedure for the desiccant used in the ST-7XE, 8XE,

9XE, 10XE, ST-10XME and ST-2000XM. The desiccant absorbs moisture in the CCD chamber,

lowering the dew point below the operating temperature of the cooled CCD, thus preventing

the formation of frost. The desiccant is contained in a small cylindrical plug that screws into the

chamber from the rear. In normal operation the useful life of the desiccant is over a year. If the

CCD chamber is opened often, the desiccant should be regenerated when frosting is noticed.

Follow the procedure below to regenerate the desiccant:

1. Unscrew the brass desiccant container from the rear of the camera and

remove the O-ring.

2. Plug the resulting hole by screwing in the supplied bolt or plug 2 or 3 turns.

Finger tight is adequate. Don't put a wrench on it.

3. Heat the desiccant container in an oven at 350°F (175 deg C) for 4 hours. The

solder used to seal the can melts at 460 degrees F, so be sure to stay at least 50

degrees below this number. Preheating the oven to avoid hot spots is

advised.

4. Replace the desiccant container into the rear of the camera, being careful to

reinstall the O-ring and insure that it does not get pinched.

5. Expect the camera to take an hour or two to reach the frost free state. If it

does seem to frost and you need to capture images, reduce your cooling to

the zero degree C range - the CCD dark current will still be quite low.

 

William.

[ollypenrice]

That's a great post from William.

Don't worry about the screen stretch you see in the capture programmes. That's all it is, a crudely stretched visualization of the still-linear data.

I agree that the camera seems to need a good dry out and warm up with attention to the dessicant.

Can't say I've ever rated the separate guiding chip since it looks through your filter and if this is Ha you're going to struggle. Also you have to rotate the camera to find a guide star. Seems like a pain to me.

Olly

[nmoushon]

William - Thanks a bunch! Very detailed post and I've already found it in the user manual I have. Never in a thousand years would I have guessed to put a imaging compenant in the oven at 350....never lol. I will be doing that tonight after work. I have a look at the new CCDOps manual...I have the older one but its 9 years old. Thanks for the links.

Olly - I haven't worked much on getting the guide chip to work yet. PHD is having trouble finding the camera so thats something I'll try to work on while that piece is in the oven. You make a good point with having trouble finding a guide star...especially when you tack filters in front of it. I only have LRGB at the moment but I am looking at Ha filter down the road...once the wife forgets about this big purchase a little  One thing I have going for me is that I'm shoot at a pretty widefield with my .76x reducer which brings my ED80 to 380mm FL. So at that length I would think I should have to much trouble finding a guide star....I hope. Posts on CN have nothing but praise for the guide chip so I can only hope I'm as luck as those posters. I could definately see it becoming more of a problem when you get to longer FL.