Antares 2" - 70° Eyepiece - Built in coma corrector

[johninderby]

Came across this and wonder if it's actually any good at all. Interesting concept if it works. About £150.00 delivered.

Antares MER30 - 2" eyepiece with coma correction for Newtonians with f/4.5 or faster

http://www.teleskop-express.de/shop/product_info.php/info/p2889_Antares-2--Weitwinkel---70----mit-Koma-Korrektur-fuer-Newtons.html

A 2" wide field eyepiece, especially for fast Newtonians - this is the main characteristic of the Antares / Sky Instruments MER30. A six-element Erfle design has been combined with a two-element coma corrector. The result is an excellent field correction even with f/4.5 Newtonians or faster.

A comfortable wide angle eyepiece with 30 mm focal length for large true fields. With a weight of only 320 g it is also suitable for lightweight Dobsonian telescopes without compromising their balance.

Technical details:

-- Focal length: 30mm

-- Number of elements: 8, incl. coma correction

-- Apparent field of view: 70°

-- Eye relief: 20mm

-- Barrel size: 2", with 2" filter thread

-- Weight: 320 Gram

John

[rwilkey]

That looks a good deal if it works as well as it suggests, although I am OK at this focal length, I see the Erfle designs are generally being more recommended for faster scopes, interesting, would love to see a users review of this one.

[John]

I seem to recall erfle designs (at least the ones I've tried) being useful in scopes slower than around F/7 but not so good in faster ones. Antares had a 30mm modified erfle design on the market for quite a few years which was reputedly better in faster scopes though not perfect by any means. It looks like they have taken that modification a step further with the one that John links to. The price has gone up as well of course

Addressing coma within the design is an interesting approach though. I wonder how it would perform in scopes that don't suffer from coma ?.

If the eyepiece could deliver a well corrected 80 degrees AFoV in fast scopes that would really be interesting for that money

[johninderby]

Cloudynights review.

http://www.cloudynights.com/item.php?item_id=252

From Astronomie.de

http://translate.google.co.uk/translate?hl=en&sl=de&u=http://forum.astronomie.de/phpapps/ubbthreads/ubbthreads.php/topics/156414/Erste_Erfahrungen_mit_dem_Anta&ei=HQlFToO0JIXChAf45Nj_BQ&sa=X&oi=translate&ct=result&resnum=8&ved=0CGEQ7gEwBw&prev=/search%3Fq%3DAntares%2BMER30%2Bforum%26hl%3Den%26rlz%3D1T4PCTC_enGB350GB350%26prmd%3Divns

John

[rwilkey]

Thanks for the reviews, I'll stick with what I have already, I think

[johninderby]

I'll stick with what I have already, I think

So will I.

However if Televue ever brings out an eyepiece with built in coma corrector then I would be tempted.

John

[25585]

Cheap glass waiting to be tried out in my Thirtysomething bunch.

It seems to be a typical Erfle with coma corrector. I hope my Vixen 30 NLVW is better, it also has most lenses at top, then a large 1 or 2 lower down. Maybe it's a Barlow though......

 

[Louis D]

That design boggles the mind.  Why coma correct the outer region when coma is already swamped by various eyepiece aberrations?  Had they started with a Panoptic clone, it would have made more sense.

[25585]

2 minutes ago, Louis D said:

That design boggles the mind.  Why coma correct the outer region when coma is already swamped by various eyepiece aberrations?  Had they started with a Panoptic clone, it would have made more sense.

I will try it in both frac and newt, as well as SCT. Even 35mm Panoptic needs the Paracorr to improve (but can just be OK on its own at F5) so lesser eps I expect to be worse. This Antares is 8 element with CC being 2. Standard Antares Erfle are 5 or 6 according  to their literature.

The proliferation of cassegrain and long FL refractors has allowed poor or semi-acceptable eps to be accepted as OK for visual. Only the fast FL users have really encouraged and driven development of actual wide field, well corrected eps as far as we have at present.

So what's next? Maybe auto focus, as in photographic lenses, proper optics with electronics. For zooms, some prime. Programmable for fl of scope, fov, even eye relief. If an eye piece with movable elements can be made, again as for camera lenses, that will be innovation! Binoculars and terrestial will lead the way.

[Louis D]

15 minutes ago, 25585 said:

I will try it in both frac and newt, as well as SCT. Even 35mm Panoptic needs the Paracorr to improve (but can just be OK on its own at F5) so lesser eps I expect to be worse. This Antares is 8 element with CC being 2. Standard Antares Erfle are 5 or 6 according  to their literature.

Another 30mm Frankenstein eyepiece for you to try if you have the parts as I do: 1. 30mm Widescan III clone with 80 degree AFOV., 2. TS - 2'' Field Flattner - Universal Field Flattening Lens, 3. 2" spacer rings or threaded extension tube.

I found that those 30mm 80 degree clones' biggest problem is field curvature making their edge of field aberrations look worse than they are.  I put several inches of spacing between mine and my TSFLAT2 that I normally use on my 72ED frac.  It helped to flatten the field and reduce edge of field astigmatism.  Most of the "going to warp" description I've read from multiple reviewers is due to its field curvature, not astigmatism.  Not a practical eyepiece solution, but fun to play with if you already have all the parts.

[25585]

There was a CN post on the Superview eps that said the 30 was worse thsn 40 and 50, but if you focus between edge and axis, all should be acceptable in respect of FC. Seems like terrestial technique slightly.

[25585]

Mine has turned up. 

All the lenses are in its black barrel. The screw on chrome stem is just tube. 

Be interesting to see if the coma corrector works on its own & with a Paracorr. 

It's shallow eyecup peels back to bare metal rim, or pulls off altogether. There are threads inside the eye lens end, but whether they were intended to facilitate assembly or for camera adaption etc I don't know. The latter is possible given intended coma correction.