Telescope Reviews: Nagler vs BO for planetary viewing?

The task is planetary viewing with eyeglasses and choices for consideration are: Nagler T6s, Radians, or BO/TMB Planetaries.

I've used all three extensively (I do not wear eyeglasses). The T6s I did not like for planetary. While excellent general purpose EPs affording wonderful wide-views, I felt their on-axis clarity was not as good as other eyepieces when dealing with planets. Eye relief, while also fine for non-eyeglass wearer, was still close to get the full 82 deg AFOV. So I imagine might be a bit difficult for you since you wear glasses. Given that it's also handy to have lots of focal lengths in small increments for planetary, the T6 line does not offer as much selection as the other two, and is also much more expensive with 4 EPs used costing you nearly $1000.

Radians and BOs both great in the eye relief department, but the Radian definitely feels like more comfortable distance. While the BOs advertise a 60 deg afov, it is smaller. Mine measured around 57 deg and the difference is readily apparent when comparing directly to a Radian. Between the two, overall, I feel the Radian gives better on-axis resolution for planets and shows more subtle low contrast details. For my eye I put it a clear notch above what the BO produces for me. Price-wise though, a bit of a different story as a used Radian will cost you around $100 more than a used BO. However, swinging the other way now, availability of the BOs is spotty and they are hard to come by since production is not regular thing with them. In addition, the newest BOs which I believe the 6mm may be ready, have an increased price tag and new will probably be around $100 I suspect and not $59 like the previous ones.

So working with a used price of $170 vs $75 (Radian vs BO), is the extra $100 worth it? For me the answer is yes. Besides providing planetary performance which always challenges or equals my best 4-element Orthos, they also provide excellent performance across all other targets, and do particularly well IMO on nebula (e.g., like M57) being nice and contrasty and also showing star colors in clusters and in doubles much more prominently than in other EPs. So given the better performance on low contrast planetary detail and the across the board excellent performance on other targets, plus the little wider AFOV at a full 60 deg and longer feeling eye relief, the Radians would get the nod from me (and have as I've recently replaced my BOs with Radians).

But regardless of any extra performance edge to the Radian and being that both are really good optical performers, price always drives everything, so the question becomes if you plan on getting say 4 EPs, the choice between these two really comes down to can you afford $680 vs $300 (used prices)?

For your 80mm, of course EPs at the shorter FLs in the Radian line would be best for Planetary. For your C6, which I also had, the 14mm, 12mm, 10mm, and 8mm would make a good range (I found that 12-10mm usually range produced the crispest image on the vast majority of evenings in my C6).

-Bill

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250mm f/4.7 Orion XT10i Dobsonian
102mm f/8.0 Tak TSA Super-APO
66mm f/5.9 WO ZenithStar SD APO
40mm f/10 Coronado P.S.T.

Edited by BillP (09/26/08 11:26 AM)