Space-walking with the Meade MWAs: these new 100[degrees] eyepieces offer users vast fields and good ergonomics.
I began my love affair with large AFOV oculars in the early 1990s after I got a look through a Tele Vue Nagler eyepiece. Its 82[degrees] apparent field forever spoiled my 55[degrees] Plossls for me. About seven years ago, things got even more serious when 100[degrees] eyepiece designs entered the market. Suddenly, the 82[degrees] eyepieces I loved didn't seem as special anymore. So, did I go out and replace all my oculars with 100[degrees] wonders? No. There was a problem: cost.
Ultra-wide eyepieces were priced at $600 and up, which kept my inventory down to two. That could change now, however, with the introduction of the modestly priced Series 5000 Mega Wide Angle (MWA) eyepieces from Meade.
The MWA series consists of four eyepieces with focal lengths of 21, 15, 10, and 5 mm. While it would be nice to have an ocular with a longer focal length than 21 mm, it's not as necessary with 100[degrees] eyepieces as with narrower ones. The 21-mm covers a large true field and is actually a better performer in light pollution than a lower-magnification eyepiece, tending to spread out background sky glow.
When using multiple eyepieces, optics are only part of the story. Equally important are their mechanical characteristics, not just for durability's sake, but for ergonomics. If it's difficult to properly position your eye at the eyepiece, it doesn't matter how good the glass is. The MWAs look modern, but unlike some oculars, their barrels don't get in the way of proper eye placement.
The Mega Wides are equipped with rubber grip rings and feel good in your hand. Their finish is outstanding, and removing the caps from the eye and field lenses reveals perfect-looking greenish lens coatings (they are fully multi-coated). All visible interior surfaces, particularly the eye lens and field lens areas, are well-blackened to reduce light scatter. Each eyepiece is threaded to accept standard filters.
Was there anything I didn't like about the MWAs' mechanics? Their rubber eyecups tended to become detached. When I folded an eyecup up to block stray light, it would often pop off and I'd lose it in the grass on a dark observing field. But this is a minor quibble.
The first thing I did after the MWAs arrived was to check their two most important specifications, eye relief and apparent field. While Meade publishes these specifications in their promotional literature, my motto is "trust but verify."
Eye relief is the distance you need to position your eye from an eyepiece to take in the entire field of view. Meade gives eye relief figures of 20 mm for the 21- and 15-mm eyepieces, 19.7 mm for the 10-mm, and 13 mm for the 5-mm ocular, and my measurements confirmed they were correct. Even 20 mm is not much eye relief for those who wear glasses while observing, but it's still fairly generous for ultra-wide-field oculars.
To roughly determine the MWAs' apparent fields, I timed how long it took a star near the celestial equator to cross the field in an undriven scope. I then converted that figure to AFOV. The three oculars with longer focal lengths were close to Meade's 100[degrees] specification. Only the 5-mm came up a little short at about 94[degrees].
I also checked for pincushion and barrel distortion, though slewing around dense star fields, which revealed little evidence of either problem to my eyes.
Meade also claims the MWA series are parfocal, meaning that they reach focus at the same point. That's not quite true in practice. The 21- and the 15-mm models are 2-inch eyepieces and are indeed parfocal with each other, as were the 10- and 15-mm eyepieces. But the 10and 5-mm eyepieces have lV4-inch barrels and must be used in an adapter, which usually places them farther out in the telescope's focuser. As such, they don't focus at the same place as the 2-inch eyepieces.
This seven-element eyepiece is the most physically imposing of the MWAs, and is something of a handful at 1.68 pounds. In performance, the 21-mm was paradoxically the most and least impressive of the set. Its huge field was breathtaking, but stars more than 80% of the way to the edge of the eyepiece looked misshapen in my f/5 Dobsonian reflector.
Much of this was due to the star-distorting coma inherent in a short-focal-ratio telescope. When I added a coma corrector, star appearance improved considerably across the field, but some residual astigmatism in the eyepiece design meant stars toward the edge were still not perfect. Unsurprisingly, edge-of-field stars looked better in my f/10 Schmidt-Cassegrain telescope.
I found it important to keep my eye close to the eyepiece's optical axis. Move it to one side and performance was poorer. I'd get "kidney-beaning," bean-shaped dark patches in the field of view, and also some spurious color on bright objects. In practice, it was not hard to position my eye properly and soon became second nature.
While it doesn't offer the space-spanning views of the 21-mm, the 1.4-lb., 15-mm MWA shows a nice wide swath of sky and its shorter focal length is less demanding of the optical design. Stars at the field edge were respectably round, both due to coma being less prominent because of the 15's lower astigmatism and its higher magnification. Eye placement was also less critical than with the 21-mm. Despite the presence of eight lens elements (which could dim the view by absorbing some light), objects seemed just as bright as in other 15-mm eyepieces with fewer lenses.
Like the 15-mm, the 10-mm is perhaps a better balance of field size and optical quality than the 21-mm. Stars were small and well shaped at the field edge in my Schmidt-Cassegrain, which made star clusters look great. The 10-mm became my "glob buster," making short work of smaller globular star clusters like M92 in Hercules, delivering plenty of tiny stars on a dark background. This one weighs in at a fairly modest 14.7 ounces, and, like the 15-mm, incorporates eight lens elements.
While the 5-mm came up a little short in the AFOV figure, it acquitted itself well in every other regard. Stars were better at the field edge than in any of the other MWAs. Perhaps the greatest compliment I can pay this ocular is to call it a good planetary eyepiece. Saturn was beautiful in my Dobsonian at 250x, and its wide field meant I didn't have to continually nudge the scope along to track. This nine-lens-element eyepiece weighs only 11.8 ounces and handles like a normal eyepiece.
I thoroughly enjoyed observing with the MWAs, but beyond the fun, there were a few surprises. The biggest was how well they stacked up to my premium 100[degrees] oculars in use. Stars at the edge of the field were not as good as in premium oculars, but even with the large, low-power field of the 21-mm that rarely bothered me. I was concentrating on the eyepiece center most of the time, and only bright "problem" stars on the edge of the field normally caught my attention. Still, when directly compared with the more expensive eyepieces, the MWAs presented a slightly softer view overall.
After my testing was done, I just had a ball space-walking with the Mega Wides. The MWAs are good performers by any standard, and the fact that they don't break the bank to deliver means I can't help but be enthusiastic about them.
WHAT WE LIKE
Generous field of view
WHAT WE DON'T LIKE:
Rubber eyecups wouldn't stay put
Meade Series 5000 Mega Wide Angle Eyepieces
U.S. price: $199.95 to $249.95 Available from Meade.com and dealers worldwide
S&T Contributing Editor Rod Mollise loves the view through a quality eyepiece.
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|Title Annotation:||S&T Test Report; Meade Mega Wide Angle Eyepieces|
|Publication:||Sky & Telescope|
|Article Type:||Product/service evaluation|
|Date:||Aug 1, 2016|
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