Quote:
Originally Posted by Jules76
I was under the impression that this "x1 to x1.2 per mm of aperture rule" was under average viewing conditions. When the seeing is really good you can expect more. At least this has been my experience.
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In good steady seeing X1 per mm of aperture will allow your eye to resolve the Airy Pattern. In poor seeing you will need more than this to catch glimpses of the disc and ring structure due to it boiling and breaking up. This equates to about 25X per inch.
When people talk about still gaining detail at magnifications of 50X or even 100X per inch, I just know they do not have great seeing as I call the point above which you can see the Airy pattern `image breakdown' . If you are looking at the trapezium in M42 for example at X300 you are clearly seeing the first diffraction ring around each star with a 12" scope, what is the point of increasing the power? I would be backing off th epower until the stars look like pinpoints.
Usually when people talk of using 100X per inch they are usually talking about looking at the Moon or Saturn , which seem at least from an aesthetic point of view to be able to stand much more magnification than is necessary.