To be honest I think I just got a bad one. It had really bad ghosting and kidney beans all over the place was clear in only the inner 40% if I don't count the ghosting. I had one previously and it preformed much better. Again I think it was just a bad one so I returned it.
It's a good eyepiece especially the price.
Very happy with this purchase. This is a great eyepiece. The Erfle design is dated, but it was a super wide field design years ago and it certainly works well today. Hard to beat for the money!
If you want the widest possible field of view from a 1.25 inch diameter ocular, the TPO 30mm fills this need. You can go with a longer focal length eyepiece, but they all have narrower apparent fields of view. You get a "looking through a tunnel effect." If you go with 20 to 24mm ultra wide angle, you get edge distortions. The 30mm is a perfect compromise: a fairly wide apparent field of view with pinpoint star images to the very edge of the field.
So far I really like this eyepiece. this is the first time buying a 2 inch eyepiece. It's a good eyepiece for not a lot of money.
I have the 50, 30 and 20 mm eyepieces. I am using them through an Orion 10 Astrograph Newtonian and I am very happy with them. They are very clear and the focus is easy. If you are looking for an eyepiece that performs well at an affordable price then consider these. I would purchase them again if something happened to the ones I have now.