This was a problematic image for me, but it was all my own fault!!
The image was to be a ripper consisting of 15 X 20 minute images but alas I didn't check my focus during the imaging session and with the temprature dropping from around 13 degrees to 3 degrees in a couple of hours my focus drift was quite large.
Anyone who knows these scopes will be aware of the small critical focus position and how a small change can totally stuff an image.
I ended up with 5 X 20 minute exposures I could use.
The image was cropped a little to get rid of some Ice which formed on tthe bottom of the CCD due to the low tempratures. Camera was somewhere around -40 degrees C.
Looks ok, Hagar. I can never get anything decent on that one either!
On a side note, did you know you were in Astronomy Magazine a month or so ago, Mike? Do you really lift boulders??
Which issue (month) was that? - PM me. I've had a few images published in US Astronomy but I assume you are refering to a bit of a Bio on me...? Err yes, I "used" to lift boulders
I agree, not too bad Doug. That must have been annoying though 5 hours of exposures not to your liking.
FSQ needs refocusing as you say about every 2C change in temp.
So if a cold change comes through then it'll be off. You can get a temperature compensating robofocus. You train the robofocus software to the scope and its temperature changes and it will adjust automatically.
Doug, you might want to chat to Monte Wilson. He got that sorted out by heating and insulating the OTA tube to keep both ends within a very small temperature differential. Some kind of regulated dew heater system. I think it's working great for him.
Opps. Picture's great by the way. Nice colors and tracking. Stars a bit overwhelming and soft though due to your focus.
Quote:
Originally Posted by gregbradley
I agree, not too bad Doug. That must have been annoying though 5 hours of exposures not to your liking.
FSQ needs refocusing as you say about every 2C change in temp.
So if a cold change comes through then it'll be off. You can get a temperature compensating robofocus. You train the robofocus software to the scope and its temperature changes and it will adjust automatically.
Greg.
Last edited by multiweb; 16-09-2009 at 09:04 AM.
Reason: nice pic
It looks pretty good for only 5 subs. Not much noise (mostly introduced from the resample for the forum no doubt) and colours look great too. I did this myself last year and managed to get 6 x 12 on it, but it was from light polluted Adelaide. On list for another shot at it from Clayton.
Oh boy, loosing 200 minutes due to focus shift, I feel for you Doug, that would drive me crazy.
At least you got some data to use and it's turned out nicely for 100 minutes mate.
I stuffed up in a similar way one night because I hadn't tightened the clam shell onto the mount all the way down, it was just ever so slightly loose giving it a bit of play and half the data was ruined.
Thanks for the comments everyone.
Paul, Would be good from your dark site. It is fairly dim and takes a bit of teasing.
Andrew, Not as bad as the night I setup to shoot 5 hrs of 30 min exposures and forgot to start guiding. You can imagine 5 hrs of star trails, not nice.
Doug, one would hope you either had a carbon fibre tube or temp compensating focuser? 5 hours of not checking and adjusting focus makes you a bad boy
Mike
Te mperature was already down to -2 degrees and had been there for quite a while. Went to bed and left everything running overnight. Except my guider of course.:confu sed2:
NGC 6188 Tak FSQ106ED & QHY8
