Posted By James C Chandler Jr
Apologies for 'too much information' biographical info, but this 'mini-review' is perhaps best judged considering my limited experience and specific application.
Test scopes include an F6.5 C102mm achro refractor w/2" dielectric diagonal, F3.75 SV 80mm achro finder (modified with a 1.25" mirror diagonal & homemade focuser), F4 50mm Antares finder (modified with a Borg focusing 1.25" astro prism), and CPC 1100 SCT w/AP visual back and dielectric diagonal.
Have become fond of small fast refractors for wide sky views. Since the CPC 1100 is really nice up to about 1 degree FOV, the idea was to piggyback a couple of small scopes to supplement simultaneous views in 2-to-4 degree FOV, and 4-to-8 degree FOV.
For really wide views, excessive aperture is supposedly 'wasted' with too-large exit pupils, so it seems logical/economical to get wide views from relatively small fast scopes with relatively short eyepieces, rather than a bigger scope using some 40mm monster heavy eyepiece. At such low magnification, haven't noticed excessive visual achro color from the fast inexpensive refractors. Initial experimentation with inexpensive scopes, makes me suspect that the typical inexpensive fast achromat might be 'pretty good' nowadays. Or maybe my eye isn't good enough. Take yer pick.
Anyway, started out experimenting with various inexpensive eyepieces. The nicest inexpensive EPs I tried included Expanse and Q70, though those have some edge fuzziness on fast refractors.
The first two premium EPs tried, were 24mm Pan and 13mm Nagler T6. Pan 24mm seems 'almost perfect' in the fast refractors and it works great in the F6.5 and F10 scopes too. Pan 24 has comfortable non-eyeglass eye relief for me.
The 13mm NT6 works great too, but eye relief seems a little tight. Maybe my eye is too deep in the socket, or eyelashes too long, but the most comfortable eye-placement for the 13mm T6 is far enough back that the visible Apparent Field is about the same as the AFOV of the Pan 24. Which is fine, because that is 'wide enough' fer me. If I get close enough to the 13mmT6, to see the field stop, my eyelashes smear grease all over the eyelens. It is probably a personal eye anatomy issue, because many users don't report that problem.
I wanted additional 'premium' choices in the mid-focal length. Selection criteria:
1. EP not incredibly heavy.
2. EP not ridiculously long.
3. Eye Relief preferably greater than 12mm.
4. Good edge correction.
5. Preferably a 1.25" eyepiece.
Those restrictions seemed to rule out 16mm Nagler T5, 17mm Nagler T4, or most Speers-walers. Pentax XW or Vixen/Stratus/Hyperion are somewhat physically large and/or not available in desired focal lengths.
WO 16mm UWAN seemed possibly worth a try, but WO doesn't sell a 'parfocal' UWAN in the 10mm ballpark.
Axiom LX reviews are somewhat scarce, but the few reviews found are positive re optical performance. Axiom LX are not ridiculously heavy or long, and nominally parfocal, though the 'pregnant guppy' physical appearance doesn't immediately look like a strong marketing asset.
Anyway, after several nights testing, am pleased with the Axiom LX 15mm and 10mm. They work good in the CPC 1100 (F10) and C102 (F6.5).
The Axiom LX 15mm and 10mm in the tiny fast refractors, seem about equally well-corrected with the Pan 24 and Nagler 13mm T6. On wide views, on all four EP's, the view is crisp except at extremes of the FOV. On extremes of the FOV on the F3.75 SV F80, stars are rounder than perfect points, but remain well-focused as far as my eye can tell. No 'comet-like' smearing of the stars anywhere in the FOV.
By comparison, the Expanse 20mm and 9mm get noticeably more fuzzy at the edges, and the Expanse AFOV is noticeably narrower, though they perform pretty well considering the cost.
In another comparison, the Antares finder EP and the SV 23mm finder EP, have much narrower nominal 50-ish AFOV, and stars are noticably large blobs past halfway out from the narrow AFOV. So an Expanse seems much better than a typical Finder EP, and the Pan, Nagler, or Axiom LX seem much wider and crisper than the Expanses.
The Axiom LX eye relief seems somewhat better than the Nagler 13mm T6. Adjusting the eye position to avoid eyelash-smearing the eyelens, the AFOV looks somewhat wider than the Nagler 13mm T6 to my eye anatomy.
The Axiom LX seem about as bright, with similar contrast, as the Nagler T6 and Pan 24mm. The Expanses look 'perceptibly' dimmer than the Televue and Axiom LX EP's, though the Expanses work awfully well considering their price.
The fat-wide 'pregnant guppy' configuration of the Axiom LX isn't as un-ergonomic as I expected. In fact, it works pretty well. By adjusting the eyeguard just high enough to keep eyelashes off the eyelens, I can lightly rest the bridge of nose on the wide eyeguard and reliable keep the eye in the 'sweet spot'.
Axiom LX seems to work pretty well overall. Was impressed enough to order a 7mm Axiom LX.
They seem to work quite well on fast small refractors, but haven't the foggiest idea if they would give similar performance on a fast newt. Fast big newts might be an entirely different ballgame than small fast refractors or 'big' SCT. Dunno.