There was still some darkness left after I finished imaging asteroids on Tuesday night but the moon had risen so the skies were not really good enough for photography. So I decided to try hooking up the CCD to my 5" refractor.
The scope is an 5" achromat and nearly as old as I am, so there is some residual colour which made me wonder how good the system would focus, especially without an IR blocker in place, but what the heck. Why waste clear skies?
Below is one result. It is a combination of 5 3-minute exposures with an ST-8 (non-E) binned 2x2. I am quite pleased with how it came out. The brighter stars do show some enlargement due to chromatic abberation, but not as much as I expected for such a short focal ratio. I have not yet had the time to measure the field of view, but it appears to be about 1.25* x 1*. It will be interesting to try some nebulae with a red filter.
Comments welcome.
Maurice
The scope is an 5" achromat and nearly as old as I am, so there is some residual colour which made me wonder how good the system would focus, especially without an IR blocker in place, but what the heck. Why waste clear skies?
Below is one result. It is a combination of 5 3-minute exposures with an ST-8 (non-E) binned 2x2. I am quite pleased with how it came out. The brighter stars do show some enlargement due to chromatic abberation, but not as much as I expected for such a short focal ratio. I have not yet had the time to measure the field of view, but it appears to be about 1.25* x 1*. It will be interesting to try some nebulae with a red filter.
Comments welcome.
Maurice
Attached Image:
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