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Final Release for EP Eval Form

Started by wpaolini, 09/15/2006 09:24PM
Posted 09/15/2006 09:24PM Opening Post
The attached images are the final incarnation of the form modified based on my 1st use of it for the 5mm eyepiece comparison.

Major changes include limiting the afov areas to 3 regions instead of 4 because 4 was too difficult to judge accurately. Other change was in scoring and instead of just having a composite score, layed out scores for each major area as different things are more or less important for different makes it a little fairer or evaluation-friendly. Narrative is the same pretty much and included in main form although not shown in the attached image to keep under the 500K file size restriction on the forum.

If anyone wants a copy emailed to them, shoot me a note with your address.



5mm TeleVue Radian (1st Place for Planets, Globulars, Nebula):
Clearly a well corrected eyepiece! Star images remained intact to almost the extreme edge. Star point size was only average compared to the rest. On Jupiter it suffered from some internal reflections and many eyeball glint reflections, to the point of being not annoying but very noticeable. Eye positioning was also sensitive, giving partial blackout if not correct. This again was not annoying, except on the Moon where it happened more than I liked. It also suffered from some fairly significant CA off-axis. This showed as very noticeable on Jupiter and 1st magnitude stars. On 2nd magnitude stars it became much less detectable. I did not see any CA on stars dimmer than 2nd Magnitude -- for normal viewing of clusters CA was not apparent. On Jupiter is also showed quite a bit of CA, but again, the extra detail it showed on the surface negated that problem. Overall stars also had a warmish or yellowish cast. This was especially noticeable when switching to any of the other eyepieces in the comparison. Therefore, for the majority of celestial objects, the CA, although sometimes significant, was not much of an issue in practical use. However, despite all these issues, and while the Radian was not the sharpest eyepiece in the bunch, it clearly put up the most detailed on-axis view of Jupiter. So of the bunch, it came in #1 for Planets showing much more details in the bands and festoons of Jupiter, so much so that it diverted ones attention from the CA on Jupiter’s fringe. So as far as planetary performance is concerned, of the bunch I was getting the best resolution of fine detail on Jupiter with the Radian 5mm – however, the Siebert 5.9mm Star Splitter was only ever so slightly behind showing detail and further behind showing atmospheric shadings due to its neutral coatings. The others fell well behind, even the SuperMono which for me was performing only a very slight tad better than the UO HD.

On Globulars the Radian also came in #1 for both an expected and unexpected reason. As expected, its wider AFOV at the 240x magnification in my scope, and therefore wider TFOV, put the Globulars (M13 for this test), and nebula (M57 for this test) in more context with the surrounding star field making them more pleasing and interesting to observe. Unexpected was that it’s average star spot size seemed to work as an advantage for Globulars , accentuating the larger brighter stars while still showing finer points for the dim stars. The effect overall was that it gave the globular a more 3 dimensional look. So the Radian was #1 for high power views of nebula, Globulars and planets. It’s performance on the Moon and general star fields was not as well as some of the contenders. Star colors also did not seem to translate as well as they did in the other eyepieces. White stars had a bit of a warmish tint, red stars did not come across as red, and yellow stars seemed overly so. So for color contrast doubles or multi-color stars in Open Clusters, the Radian was not the best choice; it does however have a definite high-power niche excelling on Planets, Globulars, and Nebula.

5mm TMB SuperMono (1st Place for Lunar Detail):
The SuperMono’s reputation precedes itself as the ultimate for resolution and contrast. I had never used one before so had many great expectations. Unfortunately, for the majority of objects observed, it did not perform well in my fast Dobsonian. On Jupiter it showed minor CA even on-axis. The biggest issue however, was the outer 50% of the AFOV was very soft, too soft for serious observing and evidenced as bloat on star images. And while the central region was sharp, this was small given its total AFOV of only 30 degrees. On stars it was also a less well corrected lens and with my fast f-ratio mirror coma appeared starting at the 50% mark from center and got quite moderate the last 25%. So while this eyepiece may be a great performer in optical designs without coma (APOs, Achros, SCTs, etc.) it is apparently not a good choice for fast Newtonians.

On Jupiter, it’s performance fell between the UO HD and the Radian. As a high power planetary eyepiece for a Mid-sized aperture Dobsonian I would therefore not recommend it. The UO HD’s on-axis performance was very close, its off-axis performance was much better, had a wider AFOV, and only half the street price – overall the better choice. The small AFOV was also a hindrance for performance on Globulars and nebula because of the resulting very limited TFOV just did not give enough context. True it did have the darkest background FOV, and if it did have better light transmission it was not apparent on stars but only showed up in nebula where the Ring Nebula (M57) appeared just slightly brighter compared to the others eyepieces. While its performance seemed to be lacking on most objects viewed, I found its niche on the Moon. Lunar observing was just spectacular, showing incredibly more detail on-axis than any of the others. It was also very apparent that it showed more contrast as what appeared as delicate shading differences on the lunar surface in the other eyepieces popped out as significantly dark shadings through the SuperMono. While the restrictive AFOV made re-navigating back to a spot on the Moon more difficult, and the 50% off-axis image was much too soft, the reward of the extra fine detail and high contrast shades on-axis made up for that several fold! Definitely a #1 Lunar performer in Newtonians. I spent quite a bit of time examining the very rich fine details in and around Crater Clerke (Longitude: 29.8° East; Latitude: 21.7° North).

5mm University Optics HD ABBE Orthoscopic (1st Place for Stellar Color Rendition):
While the UO HD ABBE did not excel as #1 on any celestial object, it came in as a good to very good performer on everything! If I had to characterize this eyepiece, I’d say it is a generalist and a very good one, worth every penny if not more so than its street price. It’s lunar imagery was more detailed than the Radian’s and it’s star point size seemed to be a tad smaller. Background darkness was good, but still exceeded by both the Radian and the SuperMono. A special characteristic unique to this eyepiece over the others though, is that it seemed to put up a slightly brighter star and had the most neutral effect relative to stellar coloring – red stars appeared redder, whites whiter, blues bluer, etc. When circumstances are such that one needs to focus critically on stellar colors, this is where I’d reach – so its niche is very specialized as #1 for Stellar Coloring.

5.9mm Siebert Star Splitter (1st Place for Open Clusters and Double Stars):
Like the UO HD, the Siebert Star Splitter also performed admirably across the board on all objects. However, it edges out the UO HD often placing in the #2 spot behind those eyepieces that took #1 positions on particular classes of celestial object. For lunar detail it was a #2 behind the SuperMono, and it was only ever so slightly #2 behind the Radian on Jupiter putting up a good fight against both. The primary edge the Radian had on Jupiter was probably due to its warm coatings. While the resolution of the Star Splitter shows excellent details, its cooler/neutral coatings present more of a washed-out view of Jupiter’s clouds compared to the Radian. On Globulars the Star Splitter had the same advantage as the Radian with the larger AFOV, but its extremely small star point size did not work as an advantage for Globulars under these observing conditions. However, for Open Clusters and splitting doubles it did excel over the others, coming in as #1, but not by what I would characterize as an order of magnitude. While it’s focal length was slightly longer than the others, and many will say this could be a factor for any noted differences, I would tend to disagree that it was a significant factor. I did not have a 5mm Star Splitter and wondered myself how much of an issue this might be, so I did a quick compare on a few objects using a 5mm UO HD and a 6mm UO HD to see if this 1mm (240x vs 200x) made any difference in details. Flipping between the 5mm and 6mm UO HDs showed now noticeable difference in image details or quality on-axis. Because of that, I tend to believe that the performance of the 5.9mm Star Splitter is valid compared to the 5.0mm test companions and would hold true if the Star Splitter were also 5.0mm. Finally, in addition to being a better generalist than the UO HD, and almost equaling the Radian on Jupiter, the Star Splitter does have a very specialized niche where it performs #1, this was in star point size. The Star Splitter easily produced the finest star points compared to the others in my fast Dobsonian. An excellent eyepiece for splitting the most difficult of doubles, and #2 in most other categories compared to its competition.

Attached Image:

wpaolini's attachment for post 33488
Posted 09/15/2006 10:29PM | Edited 09/15/2006 10:30PM #1
Hi Bill,
First off, that was a very good review. I found that your testing showed exactly what I would have stated for these EPs.
The UO Ortho is indeed a good Jack of all trades, master of none, so to speak. It works well but does not excel at any one thing.
The Radian, though it has some defects, is an excellent EP with many good characteristics and I found it excellent in the same ways that you found.
I found your review to be comprehensive and well done.
The form looks nice and is easy to use as well as read. I think you are getting there with it now after all your hard work. I would hope that others would get the form and do a little Beta testing with it so that any bugs could be found and repaired.
Good work Bill, I applaud your hard work and well phrased review. grin

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