What is a good planetary EP for an Orion XT8 telescope?

A

ava

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The scope is packaged with a 25mm EP. What eyepiece should I get to observe planetary objects with the highest useful magnification? Should I get something like 15mm then use barlow to achieve higher power? Or buy a 6-7mm EP instead?

What brand of EP would show the details best without being overly expensive?
 
I'd go for an Baader Genune Ortho, probably 8mm for 150x. It isn't the cheapest eyepiece out there but it isn't out of the way and it is a bargain for the price given the quality. I would personally avoid barlowing up a 15mm. Cheap barlows invariably introduce distortion and any barlow lowers contrast which is the primary consideration for planetary viewing. If you want to fill out your mid range (not a bad idea) an eyepiece around 15mm is probably best. I like the Celestron X-Cel for that kind of focal length, which again is not super cheap but not terribly expensive. Failing that a Plossl will have reasonable eye relief at 15mm focal length and budget Plossls can be had very cheaply.
 
I'd recommend a 5mm Orion Edge-On Planetary eyepiece. I've tested this eyepiece personally and found it excellent. It will give you 240x which is a perfect magnification with an 8-inch aperture.
 
If you buy an intermediate EP with a Barlow, you will find that the details will suffer because of the extra glass that the Barlow adds to the light path. I have a Barlow, but I almost never use it. You can get a better view by simply buying the proper EP for what you want to see.

Having said that, I would not recommend that you push the magnification as high as you can. That just results in targets that are hard to keep in view and big, fuzzy images. In your case, with a 1200 mm focal length, anything lower than about 10 mm will be (in my opinion) creating diminishing returns.

I have received lots of criticism here for recommending Nagler EPs. I guess that is unfortunate. All I can tell you is that I like them a lot, even for planetary viewing. When it comes to quality amateur astronomy, you usually get exactly what you pay for. So, if you want to buy a new EP, then look around at what is available, and by all means stay away from the low end price-wise. If you can afford a good EP, you will not regret buying one. It will get years of use. There are good eyepieces available from Televue, Orion, and Celestron. Those same sources also provide some pretty cheap ones (well, maybe not Televue). You get what you pay for.
 
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