OK, here's the deal. last week, Meade 10" SCT at prime focus f6.3, E200 slide film, very good sky, guided with a 90 mm short tube orion refractor (too short focal length) 46 minute exposure time on this image, ST-4, Nikon FM2 in perfect working order, gradual warm up to ambient temperature of the E200 (condensate?) Kendrick dew heater on the corrector plate functioning well (no dew visible through the scope), 4 exposures, this is typical of the 4. I can't explain these halos!
Things I've checked: no stray light invading the optical tube, everything (focuser, camera adapter, T-ring etc. all black) camera is OK, nothing in the light path, no car headlights or other sources of light polution, corrector plate has very minor dust, no obvious problems with the primary or secondary. Has anybody ever seen this phenomenon before? I have shot satisfactory images with this optical tube many times with no issues like this. This is my first experience with E200. A barlow on the 90 would help the streaked stars substantially, but there is a lot of flexure in the focuser/extension tube/barlow/ST-4 combination that makes locking on to a good guide star hit and miss. I hope these pictures upload, I've had problems with my browser before.
Mike
Mike
Things I've checked: no stray light invading the optical tube, everything (focuser, camera adapter, T-ring etc. all black) camera is OK, nothing in the light path, no car headlights or other sources of light polution, corrector plate has very minor dust, no obvious problems with the primary or secondary. Has anybody ever seen this phenomenon before? I have shot satisfactory images with this optical tube many times with no issues like this. This is my first experience with E200. A barlow on the 90 would help the streaked stars substantially, but there is a lot of flexure in the focuser/extension tube/barlow/ST-4 combination that makes locking on to a good guide star hit and miss. I hope these pictures upload, I've had problems with my browser before.
Mike
Mike
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