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Thanks for your input David and all of you who helped me. Few more questions if I can bother you.
Since last post I was lucky to upgrade my telescope and camera. I’m now using 150mm x 750mm Skywatcher achromat. I know that achromat is not generally accepted scope for taking nice images, but I hope that for the purpose of Photometry and maybe Astrometry it will be good enough. I want to get 2 to 2.5X Barlow to increase depth of the image I can take with this scope. I’m looking on GS 1.25” 2.5X Apochromatic Barlow – any comments on this one? I own Meade LX90 8” scope on wedge that would be most likely better for the task. Unfortunately the scope is too heavy for me to set up. The 6” refractor on HEQ5 is on permanent pier in the back yard, covered with trampoline when not in use.
I was also able to buy Meade DSI 2 camera with Outback cooler. The camera uses 16-bit A/D converter and with 8.3um X 8.6um pixels is able of exposures up to 1 hour and it can lower CCD temperature to about 25 deg below the CCD temperature (+/- 0.5 deg). The CCD temperature without the cooling would be around 28-30 Deg C at 20 Deg C ambient. I have found out very quickly that there is no point in lowering CCD temperature below the ambient temperature because CCD sensor fog out. At present I’m taking images with CCD temperature set to 15 to 20 Deg C (depending on ambient temperature) and exposure 42 sec. The image acquisition software “Envisage” supplied with the camera got one unique feature. Not only that it can align ant stack images during the acquisition but you can specify quality on the image that is acceptable. Any images that are bellow the specified quality setting (due to the seeing or the guide errors) will not be stacked. It is not SBIG camera but I could (just) afford it – so it will have to do for now.
The new setup being much heavier then previous one has introduced few problems. GoTo’s become very inaccurate and focusing very difficult. Balancing and flexure in the guide scope mounting and the RP focuser were main culprits. At present I can get 16-arc sec in Dec but over 4 minutes in RA so it needs more work.
The RP focuser is - well RP focuser. I have to swap 3 of them I had until I found one with minimum sag and most square. Unfortunately, it it also the stiffest one of the lot. I have fitted 6 to 1 vernier on it to make focusing easier. It isn’t Crayford but it makes focusing bit easier. Againg unfortunately the Crayford focuser I had on previous scope does not fit, different diameter. Custom made adapter for it would be too expensive.
I have downloaded Astrometica as David suggested and I’m learning how to use it. So far it looks good for what I need and I will most likely buy it. As for image processing and initial plate solving I use Maxim DL and I’m happy wit it.
Bit too long explanations, but necessary if you going to offer any advice base it on the equipment I have. I’m in my sixties and retired. Purchasing of new equipment takes long time and hard saving.
What I want to do.
Monitor and do Photometry on some unusual stars – like vy CMa.
Do the light curves for some nearby G and F stars.
May be, to do Astrometry on some southern binary stars that have not been looked on for few decades. I have tried it before but Web cam I had then and EQ3 mount were not good enough for the task.
Questions:
Is my equipment adequate for the things I want to do?
Is it worthwhile to use Quality settings – that is software rejecting images below the Quality setting? Up side is good images, down side is that 5 of 42 second image that would normally take 3.5 minutes can take 5 to 20 minutes (depending on seeing).
I’m using Baader fringe filler filter. Am I better off by using this filter (frequency response 90 to 98% from 480 to 660 nm) it includes UV and IF block. Would the colour fringing that my achromat scope introduce around brighter stars degrade photometry results without this filter?
Is it better to use single images lets say 42 sec or stack serval images (S/N ratio improves with stacking)
Well that’s about all I need to ask for now. By the way I’m still waiting to capture that elusive meteor from outside of solar system.
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