Quote:
Originally Posted by graham.hobart
Phil,
No one but the Hubble gets that arc per second visual or imaging, or maybe in Antarctica on a still day. 2-3 is super excellent from suburbia which is where most of us live. Where I live I am happy to see the Sun sometimes!
Mine would be 3-4 on best of days.
And capitol letters makes it seem like you are shouting.
My advice, get a DSLR. Cheap. Big chip so easy to find the target and focus. Can be modded later for extra sensitivity or cooling (ooh! sounds like a menthol condom). Lots of software for support especially Canons.
I have two CCD cameras. Both of which are on the earlier list. The Atik 314L+- super cooling and a mono camera and a nice filter wheel. I have had it for 18 months and not produced a photo i would put on here yet. The QHY 8 OSc or similar- I love it and even though blowing the cooler up by accident (and the camera being second hand) the QHY folks mended it free of charge and mailed it back to me. Now tell me that is not good product follow up. I also produced a semi decent photo within a week of having the mended one.
Bias is always good, and always good for a poke in the ribs of opinionated folks like myself.
My advice, buy something you will use.
Oh, and buy second hand.
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The 1 arc second per pixel is referring to how much angle of view is being received per pixel. It isn't referring to the seeing which is usually expressed as arc seconds as well, hence the confusion.
1 arc second per pixel would be seeing divided by pixel size ie 4 arc second seeing divided by 9 microns = .44.
This whole pixel matching thing gets into sampling theory but suffice to say 1 arc second/pixel is a rough approximation. I was using .63 as a guide and in my 3 metre scope a 12micron pixel should theoretically be a better match than my 9 micron. But I do see a drop in quality using a 5.5 micron pixel camera unless there is a night of excellent seeing.
Greg.