Quote:
Originally Posted by Wavytone
For most people it works out to be between x1 to x1.2 per mm of aperture of the telescope. Thus for a typical 200mm aperture f/10 SCT, this sweet spot is around 200 to 220X, which means an eyepiece around 8 to 10mm focal length. Magnification of x1 to x1.2 per mm of aperture is pretty much the sweet spot for all scopes that produce very distinct Airy disks - SCT's, Newtonian reflectors and Maksutovs.
Some observers will wind the magnification up a tad beyond this - x1.5 is not uncommon - on a bright object like the moon it may be a bit more comfortable if the seeing is steady enough, but you won't really see more detail.
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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.
In the past, seeing conditions in my backyard haven't been that great, so my 8mm Hyperion on my small 114m Reflector was pushing it (x112 @ 900mm focal length). So that seemed to confirm that "rule". However just recently the seeing conditions have been almost perfect for a few nights with this cooler weather and clear skies. I've been in fact able to push my scope further then what I expected. Using my 8mm Hyperion plus both finetuning rings (making it effectively a 4.3mm) I was getting a zoom of 209X with my 900mm focal length of my scope and it was still clear!
I was amazed. Viewing Saturn, I was now getting more detail then I had ever seen before with my scope. While the image was still small, I could now make out the ring across the body of Saturn (instead of just seeing it on the edges), and I could start makng out the moons (could see Titan clearly as a white dot, another was barely visable). This was something totally unexpected for me. If my maths is correct, I'm getting around x1.8 per mm aperture.
But anyway, getting back to the original question, the Hyperions are great eyepieces (I've also got the 17mm). I'd highly recommend you get the Hyperion Finetuning Rings as well. Allows you to try out extra magnification without purchasing more eyepieces, and effectively makes then 4 eyepieces in 1! Definately worked for me.
