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I've been using my OSC cameras on a Stellarvue 80mm which is piggybacked on my C11" in my observatory for 2 years. I usually do anywhere from 90s-5 minute guided exposures depending on the goal. I am using the Stellarvue flattener and the Optec autofocuser as always and backfocus of 55mm from the rear of the flattener to the camera sensor.. Here is an image using the ASI533 and the stars are tight and round all around the image as best my eyes can tell.
Now, switching to the ASI1600MM, I took 5 minute guided frames with a Ha filter and I noticed issues in 3 of the 4 corners with the stars. While seeing was below average, the guiding was working well. I re-measured the backfocus and it is correct- 55mm. Rotating the camera didn't change much and when I tried the 0.8x flattener/reducer (image attached), I got the same result. At this point, I am assuming camera tilt problem. Does that sound correct? If yes, has anyone tried the ZWO tilt adjuster? Otherwise, I need to crop which I hate to do.
Bruce
Bruce
Astronomy? Impossible to understand and madness to investigate........Sophocles, c. 420 BCE
What's the chip physical size difference between the osc and the asi1600?, I have a few tilt rings, but I find adjusting my focuser tilt or secondary mirror good enough, I can save on space for back focus using this method, this is sounds undoubtedly like tilt error that you have
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .
Ahh I see the asi1600 is bigger and will show more collimation, alighnment error towards the edge of the chip. Does your focuser have collimation screws?
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .