Old Cuss, Is it not true that if you shrink the sensor way down (say a high-resolution half-inch sensor) that you will be quite a bit more susceptible to tracking issues and atmospheric conditions just like if you had used a different longer focal-length scope illuminating a larger image circle working with a larger sensor? But anyway, thanks for pointing out that focusing exclusively on just the FOV may cause one to overlook other considerations. FOV is just the thing that I currently have the best understanding of so I am a bit FOV centric right now. As I learn more aspects of imaging, my perspective will probably change.
The smaller sensor makes tracking more problematic because the smaller FOV combined with the tracking errors may result in the photons from the target no longer reaching the target. For those of us who like the wider FOV and framing the target artistically rather than simply centered in the image this is more of a problem than for those who just center the target and go from there.
The physical size of the sensor will likely make little difference in regards to the effects of the atmospheric turbulence.
The atmospheric turbulence should be considered mostly in the following ways:
1. A longer focal length will tend to make the target occupy a larger portion of the sensor. This means that atmospheric effects will also have more potential to be seen in the final image.
2. However, if your sampling is appropriate for your atmospheric turbulence then the atmospheric turbulence will not be an evident problem.
3. If you are under-sampling then atmospheric turbulence will not be an evident problem.
4. If you are over-sampling the atmospheric turbulence will be evident if you are viewing the image in its highest possible detail.
5. If the problem is not high-level atmospheric turbulence but rather the wind is blowing your OTA around, then your image may be messed up but that should probably be classified as a tracking error.
So when we choose sampling rates (a matter of focal length of the OTA and the size of the pixels in your sensor) we choose with attention to the expected "seeing" conditions or atmospheric turbulence.
I think a lot of us simply assume that we will have 2 arc-second seeing conditions and will thus want sampling in the range of 0.67-1 APP (Arc-seconds Per Pixel). Sometimes this assumption is optimistic and sometimes pessimistic.
But some of us pretty much refuse to guide and that means our tracking is a little problematic and one could argue that choosing sampling of 1-1.5 APP might be more realistic in that situation.
It is important to remember that you simply cannot choose the perfect system. No matter how you choose there will be something(s) which is/are not ideal or best suited to what you are doing. A lot of systems will do a pretty good job and that is usually where we go with our choices - "pretty good" rather than "ideal".
Edited by OleCuss, 15 January 2019 - 05:04 PM.