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Originally Posted by gregbradley
Some great tips there Paul. Thanks.
I think I'll go with FocusMax. I have the full version trial and I'll get it going.
So do you slew to an appropriate focus star every hour then have the original image reacquired? One advantage of @focus2 and the Sky X is that is automated. Can you automate that with FocusMax or does it require additional software like CCDcommander?
Good tip about the temperature compensation. It might also be the rate of expansion/contraction may not linear with temperature changes.
The RHA has a small critical focus zone and F3.8 is going to mean spot on focus is vital.
The goo news for me is the FLI Atlas is working with my setup without too much of a bother which is great. It is working in CCDsoft but it requires the Sky X to be running at the same time (which it does anyway as I use Sky X to run my mount).
Sky X also has filter offsets for different focus settings for each filter plus it has dithering for the autoguider. So some nice features there. Also you can program as many filters as you want in an imaging run. For some reason CCDSoft was crippled to only do a max of 5.
Greg.
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How my system works is that every hour or after every sub if you like (the time is up to me to set in the command programme) the command programme (in this case CCD autopilot) stops all operations and hands over to the focus programme. It takes an image of where it is and plate solves. Then it heads to the meridian (I set it to do that and you can focus within the same field if you like but it is not as good as straight up) to focus on a 4-6 mag star. After it finds focus convergence it will return slew to the same position, do a plate solve to get back in almost the same place and then hands back the reigns to the command programme which will then further plate solve to get the system back to within the tolerance you are after. I have said in my systems I want 15 arc seconds and it does this in 2-3 slews. It all takes about 5 minutes to complete the operation. So you don't lose much time.
Now you can use focusmax on its own to simply go and focus after you have clicked on one of the buttons and it will do that. That means you need to go out now and again to make that happen. Ok if you like that sort of thing, but for me I am done with that. So a command programme is what I am recommending too.
Maxim has dithering and CCDAP does filter offsets if you like. I don't use offsets as focus looks good across the board on both sets of my filters. So I just use my Lum filter to focus with and get into the imaging. I could be more thorough and get CCDAP to do and offset measurement but it is not apparent that this needs to happen. My images seem to confirm that.
Maxim and CCDAP both allow for as many filters as you want. I reckon you ought to get into some semi automation so you can have the system doing focus for you and doing the imaging without having to go out and do that yourself. Roof operation is another matter and might involves some phone calls. That can be a bit tricky to get that working well.