I have been moaning on and on about the
coma in the old LX200 GPS and how it is not fixed by the meade 4000 F 6.3 Reducer. Then I read an article which suggested that modern refractor
FF/
FR's may work better than the specific Meade
FF/
FR. So I stuck the
SW 80 ED 0.85
FF/
FR on the Big Blue Trash Can last night and thought "in for a penny...." So bolted the ASI2600mc on and sent it off to find the Needle. Now its giving me 1700mm
FL (although plate solve says 1900), and with the 2600
mc that comes to a image scale of around 0.4". So I binned it 2 X 2. I got this...
about 4 hours of 120s (gain100, Offset 50, Bin 2x2
Now, the stars are still not the best but I think its now down to seeing and guiding because the horrible U shaped
coma in the corners and the smearing as you come in further is pretty much gone. This is a slight crop (awful gradient) but not near as tight as needed when I use the 0.63. I am both astonished (the received wisdom is that refractor reducers will simply not work with
SCT) and delighted. With some better seeing and some tweaking on the setup for better guiding I think this is going to work!
full res here...
C & C please.
Scope: Skywatcher Evostar 80ED (SW 0.85 FR/FF) on a SW NEQ6Pro
Guiding; SW Evoguide 50ED, ASI 120mm mini
Meade 8" LX200 GPS on wedge (Guided with a cheapo 50mm guidescope and a ZWO ASI 120mm mini)
Sharpstar 61EDPH II (with dedicated 0.8 reducer) with wiliam Optics 32mm uniguide
Camera: ASI2600MC pro. QHY 163M with ZWO 7nm NB filters, Canon EOS700D astro mod
Secondary mount: Skywatcher StarAdventurer
My Astrobin
https://www.astrobin.com/users/mackiedlm/