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The optimum e/p for DSO's


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The last time I saw the sky (xxxx it) I managed to pick up M81-82, by using a Silva compass and Wixey-the thrill was-well,you know.I was using a 13mm Hyperion in my 8" Dob giving me about 92x. What please is the sort of optimum mags I should aim at to give me the best look at these mysterious smudges? And what Hyperion should I get next!? Or something different for DSO's.?

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Before getting my 13mm Hyperion I used my 32mm GSO plossl more than any other EP, particularly for DSO hunting. I read a post a while ago which explained the difference in field of view between the two (68 vs 52) meant a 24mm Hyperion would give the same view as the 32mm, but with better contrast.

So I'd like a 24mm Hyperion :)

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I'm not sure there is an optimum eyepiece for DSO's because they (the DSO's) come in all shapes and sizes !.

Personally, with moderate light pollution to contend with, I find 20mm, 13mm and 8mm the most useful focal lengths for deep sky objects. I have a 31mm but that's used mostly as a finder eyepiece as the background skyglow is more apparent at lower magnifications. On really dark nights it is good for extended objects such as the Veil Nebula, M31 and framing a group of DSO's in the same field of view though.

Edited by John
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The lowest power you should consider (forgetting for the moment the different AFOV offerings on the market) is one which gives a 7mm exit pupil. Exit pupil=aperture/magnification.

So for your 8" f5 (1000mm fl?) the lowest magnification would be 200/7 = x28; this would need an eyepiece of 1000/28 = 36mm.

A standard 32mm would be a good choice.

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