Leitz 88 afov 30mm
18 mm UO HD
18mm Radian
16.7mm Zeiss 69 degree afov
17mm Nagler T4
14mm Pentax XW
10mm ZAO II
10mm Pentax XW
10.5mm TV Plossl "old style"
9mm UO volcano top
7mm TV plossl
7XW
6mm ZAO II
XW5
Well y'all used to meticulous note taking on eyepieces this is not the post for you. Last night's activities in Bob's excellent f/6 8" Newtonian dob were variously designed to see if he wanted to buy my Nagler 17mm T4 and to play around with various other available eyepieces in the box.
There's Bob's box and my box and my box includes the complete XW series and the four ZAO II series and a few other pieces of glass like a Pan 24 and the Zeiss 16.7 of which I think I have the only one in the U.S. (maybe). This is the box which at a recent elementary school star party some enterprising stocky adult used as a footstool to get up to the eyepiece of my c8 while I wasn't paying attention. Fortunately the eyepiece box proved sturdy.
OK. The first order of business was to test out the UO 9, TV 10.5 plossl, XW10, ZAO II 10, and then the UO 9, TV 7, XW7, XW5, etc., on Saturn.
The seeing was good, just shy of excellent, but stable enough to provide meaningful views. Part of the "good seeing" was a high thin layer of clouds. We had quite variable results with regard to light scatter and decided that the clouds made any evaluation of that useless. The views of Saturn on-axis were sharp, in all cases, but....
Saturn in the 9 to 10mm range
The TV 10.5 plossl IMHO seriously sucked. There was some kind of vignetting that ate up about 1/3 of the fov on the perimeter of the field of view. It seriously compromises the aesthetics of the view, if you do have tracking; if you don't have tracking, a narrow field gets narrower. This eyepiece "gets you a view" but it has no aesthetic pizzaz.
The 9mm UO had noticeably better control of the edges but still had some of that dark rim. Its performance lived up to reputational consensus that for value it's hard to beat the UO ortho for the price.
The XW10 was an "immediate huge sense of relief" from the smaller fields of the UO and TV. This matters on a dob without tracking; you want a good field so that the scope can have a bit of time to steady out after you release it so you can have "very still scope moments" to combine with the best moments of seeing. Right away you can more effective viewing with the XW10. The view is excellent, color saturation excellent, the ergonomics are superb in comparison to the other eyepieces (including the ZAO II). So the XW10 may not be the most bang for the buck but it is probably the most efficient overall outlay of money and a really great eyepiece.
The ZAO II 10mm was quite a surprise to me. I have been quite jaded by planetary eyepieces and had a very ambivalent reaction to the usefulness of my Supermono 10 which was not present at this party (sold). I have read here that some people consider the Supermono 10 to be a poor man's ZAO II. My subjective answer: No way. The ZAO II is a totally different eyepiece experience. In sum, the ZAO II is the most comfortable "specialized" eyepiece I have ever used. Its effective field of view "beats" the UO and the TV plossl because the whole field is crisp to the edge, so even though the TV plossl is nominall 52 degrees you actually have more usable field in the ZAO II at 45 degrees (don't get me started on afov of the Supermono). The eye relief is great. This is a comfortable, well made, well thought out eyepiece. It's not quite as ergonomically comfortable as an XW with the big eyecup. Bob and I were of the opinion that Saturn was not the best target to really put this eyepiece to the test vs the XW10, because you really want a more varied palette (such as Jupiter) to do that. Still I came away from this test with a health respect for the clarity and ease of use of this eyepiece. To the extent that paying outrageous sums for incremental levels of performance matters, the roughly $600 that goes into the ZAO II 10mm (which however cannot be bought separately) is money well spent. Put it this way, it would not surprise me to see it outperform the Pentax XW10 on the right night on the right object. The other eyepieces mentioned here: not bad if under $100 is what you have to spend, but if you can do it, get an XW10 (or XL 10.5).
Further notes on Saturn
We also looked at Saturn in the ZAO II, the XW5, and the XW7mm, and the TV 7mm plossl. The TV 7mm seemed much nicer than the 10.5; more of the field was usable. Bob says on-axis he can see stuff on Mars with it that he can't see with anything else and maybe he is right. The XW7mm is however a much nicer eyepiece to use, and to my mind it did as good or better than the 7mm TV.
The XW5mm began to exceed the limits of the seeing (260x) so we disqualified it from evaluation; Bob said he saw some ghosting, but I didn't.
The ZAO II 6mm provided the best views of the night on Saturn. It was just the right place in terms of magnification and overall quality. One did not seem to be giving anything up, however, in moving to the XW7, so again, my sense is that the XW series emerges from this night as one's strongest bets in terms of high performance for the buck. Nonetheless the ZAO II again impressed me with a good clean-to-the-edge view, reasonable eye relief, and an unexpectedly crystal clear view of the planet.
In sum: I came away form this part of the ocular slumfest confirmed that one can do a lot worse in life than to have a bunch of XWs. Nonetheless: I was quite bowled over by the unexpectedly sharp, clear, easy to use ZAO IIs. I had originally bought these thinking I would resell them when they achieved some scarcity value, but after one night I am having strong second thoughts. They are "jumping out" as keepers and I must say I am quite surprised, because I thought I would have a very ambivalent reaction to them, as I did to the Supermono 10. While I udnerstand the Supermonos have a following, often sell above new price, and I like the fact that Mark R. went to great lengths to make them available, well, let me put it this way: The ZAO II eyepieces "impressed the bejeezus out of me" in a way that I haven't felt since the first time I used a Pentax. And I write this as a guy who doesn't like small 1.25" eyepieces.
[U]Leitz 88[U\]
I couldn't fully evaluate this eyepiece. I will say it seems to present less of a kidney bean challenge than the other Naglers I am used to. In the 8" the power was too low and the sky a bit too gray to be stunning. The 30XW is vastly superior ergonomically. Nonetheless the Leitz 88 is a very interesting performer and it is not humongous like the Nagler 31mm so it could be a real treat for the right Dob guy. If you want a serious 30mm widefield get an XW or the Nagler 31; the Leitz, I think, is properly thought of as something you do when you've tried the other two and have the funds to indulge. I look forward to trying the Leitz in the FS128.
[U]M35 with sundry eyepieces[U\]
We checked out M35 with the Zeiss 16.7 69 degree, with the Nagler 17T4, the XW14, radian 18, UO 18, etc.
In the past I've had problems with the radian 18mm in that it seemed soft on-axis compared to other eyepieces, one night in particular I couldn't get it to split a double cleanly that the UO did. But we couldn't replicate that experience this night. The radian seemed reasonable. So did the UO which is a bit of a soda straw compared to the competition. The Zeiss is pretty much waht I wanted: the closest thing one can get to "Pentax experience" that is not a Pentax: a nice clean field to the edge, no kidney beaning, not hard to position the eye, etc. It is a reasonable but not perfect candidate to fill the hole that Pentax XW line left between 14mm and 20mm. I'm selling the Nagler T4 17mm because after using the Pentaxes for a few years I'm less and less tolerant of kidney beaning and working hard to position my eye in the right place. Basically with the NT4 to avoid darkening somewhere in the field you have to back off and if you back off you no longer have an 82 degree field. But it may be better corrected than the XW14 and the XW20 for owners of dobs under f/5, which the scope we were using was not. I neglected to try out the 16mm ZAOII but it's not exactly my idea of an open cluster eyepiece. All in all I'm happy with the 16.7 Zeiss for now, but the Nagler 17T4 is no slouch, I was unable to bring myself to sell it for years, but it is now getting ready to make the move elsewhere. The radian came off better than I had anticipated so maybe I'll look at it again; nonetheless, my experiences with the radian line have been only so-so.
That's enough for my ocular slumming. I'm sure y'all want to know about astigmatism field curvature and all of those other nice things, but this was a more personal encounter with the glass in question. The only criteria we were using was: would you like to use this eyepiece?
I knew from knocking around star parties that I would prefer the XWs to the TV products but I was quite surprised by the ZAO IIs. The other items are "as noted," the Leitz looks promising.
regards
Greg N
