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What is a good magnification for globulars?

I recently got my 200p dob, with the supplied 25mm and 10mm, and bought a BST 8mm for planetary stuff. I plan to get a 31mm hyperion aspheric for low power views, and thought i would be fairly content with that for a while.

However, at my last astro meet, a guy mentioned having a 15mm BST for sale. I said i couldn't see much use for mid-power eyepieces like that, and he pointed out that planetary nebs and globulars are good through mid powers.

With globular season creeping up, and with future views of the ring nebula etc in mind, i need to choose an eyepiece. The 15mm gives 80x, and barlowed to 160x, while this gives a decent midrange mag, but the barlowed mag is much the same as my 8mm. A 12mm would give 100x, and barlowed gives 200x, giving me useful steps of 48x, 100x, 150x, and 200x.

I think the 12mm is the better option, but then i have no experience with globs/planetary nebs. What do you all think?

After writing all that, i've just realised i could always barlow the 31mm aspheric if i really wanted something around the 15-16mm mark, but i'm going to post it anyway. I didn't type all of that for nothing, dagnabbit.

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I find my best views of globulars come through my mid power eyepiece (a vintage 10mm orion megavista) which in my scope gives 75x magnification. Higher mags are useful for the fainter globs to try and tease out a bit of resolution (eg m 53 in coma and m 56 in lyra spring to mind but i do only have a 5" scope!), but seeing a bit of sky around them always makes them look nicer!!

HTH

Adam

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With a 200mm scope, I'd say 100 - 150x is good for globs. They look great with more aperture and not too low or too high magnification.

I've seen M13 under a good sky with a clubmates 20" Dob at around 150x, it was a sight to behold.

Regards, Ed.

Edited by NGC 1502
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I use quite high powers on globular clusters - 150x can be really rewarding. When conditions are good it seems to enhance the resolution the individual stars. I've also had a peek at M13 with a 20" dobsonian - rather mind blowing :p

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I would suggest an eyepiece in the 12-13mm range. Your 8mm Bst at 150x with your 200p is a very useful focal length for many targets. You could barlow the Baader 31mm but it will increase the eye relief to a possible uncomfortable level.

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Thanks guys, i've decided on a 12mm for now, which can double up as a 6mm on those rare and special nights. Now i just gotta choose one - either gonna be a BST, or a stirling plossl from the states.

Despite great reviews and recommendations from guys in my astro group, i'm still leaning towards the BST, just because i love the 8mm so much...

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I'm starting to wonder wehther I would have been better getting the Baader Hyperion click zoom 8-24 mm I think - with a barlow you've pretty much got everything covered in one/two lens for @ £160

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