pixel size of ccd vs resolution of scope vs general seeing

Forgot the ONE MAJOR HEADACHE. When every thing is working perfect, image is great, tracking and guiding less than 0.5 pixels etc ...................CLOUDS ROLL IN :x

My feelings are the same as those cited by Michael, Dave and Kieran.

Astrophotography is like a great dish ... it takes time to cook and prepare well and certainly requires time to master each of the many intervening steps.

If you have an interest in CCD imaging, certainly start out in monochrome using simple luminance exposures so that you can master the various intervening steps and get your feet wet with Photoshop.

I image at 1.27"/pixel with my AP160 and 2.88"/pixel with my FSQ .... I am also a believer in oversampling so that you can pursue the best possible resolution that your site can make available. If necessary, we can resample downwards if the seeing does not satisfy our original sampling.

For planetary work, the route to go is with a highspeed webcam or USB/firewire device with image scales that are very aggressive (ex. 0.15"/pixel).

Anyway, astrophotography is one HUGE mountain to climb and can best be conquered in small incremental steps. There is no greater way to be turned off than by tackling everything at once.

However, and please forgive me in advance, but do you not think you're getting a little bit too far ahead. I strongly suggest you master the basics before going into such fields. You'll only give yourself awful headaches. There is a misconception that if you match the best CCD to the right scope you'll end up with great images, there is a huge amount to learn before any of that becomes a factor.
Master the basics, the rest will come with time.
After all if you do it all now, what are gonna do in a few years from now:)

Unforgivable stuff you said there Dave! Not talking to you anymore, Im putting you on my list of enemies!! Your in for it now Dave!
Seriously though, I understand your point and agree completely. All that stuff is far far in the future for me currently, and im under no illusions that if i just throw money at the problem and buy tons of expensive gear i can produce great images. I know this is not possible, as ive found even just getting a half decent image of a lunar crater with a webcam is quite difficult, and thats many difficulty levels below what you guys do.

Im not planning to buy any more gear or try to get into DSO Photography to the level of you guys at all for many years, until i at least learn to use my current rig to its full potential. I just asked the question as I was looking around at images on the web and it struck me that a camera may be too high res for a particular scope and i just wanted to know if that was ever an issue and what were the parts of the issue to consider.

Its great to know ( and see the answers in this post) that their is some of the best advice from some fantastic astrophotographers on these boards, and as i hit the aforementioned hurdles you guys all faced, you are there to offer advice and your expirience.

Happy new year all.

Fintan.

Fintan --

Like you, I'm only in the "collecting information" stage (and plan to stay there fore a good few more years).

However, one tidbit I have collected so far that hasn't been mentioned is that you can also "bin" many cameras. Essentially, this ties 4 (2x binning) or 9 (3x binning) pixels together, allowing for considerably more dynamic range at the expense of resolution. As I understand it, this can be a great benefit with very dim targets -- and might be a reason to get a camera that starts out at, say, 1 arc-second per pixel and then bin it 2x2 for 2 arc-second resolution.

Cheers,
-- Jeff.

The downside with that jeyjey is that the image will only be a quarter of the original size.

Michael --

Certainly true. However, the cost of the CCDs seems to be more closely correlated to the overall sensor size, rather than the number of pixels on it. So a 7um-pixel sensor with 2k x 2k pixels binned 2x2 would produce the same result as a 14um-pixel sensor with 1k x 1k pixels, only the binned one would have more sensitivity (and slightly more cost). Do I have that right?

But perhaps more to the point, aside from folks like Anto who get their (most excellent) work published in magazines, is there any great advantage to more than, say, 700 x 1k pixels? I assume most people look at their images on computer screens (where the extra resolution would, in effect, be thrown away). Does the extra resolution help greatly in processing before the final (perhaps only 700x1k) image is produced?

Thanks,
-- Jeff.