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Mid to High Power Eyepieces


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Pentax XW 10mm,

Tele Vue Nagler Type 6 9mm,

Baader Genuine Orthoscopic 7mm

Tele Vue Nagler Type 6 7mm

Thanks to First Light Optics, over the past few weeks I’ve had the pleasure of borrowing a couple of very nice eyepieces in the medium to high power bracket, the Pentax XW 10mm and the Baader Genuine Orthoscopic 7mm.

It’s been very interesting comparing them to my Tele Vue Nagler Type 6 9mm and 7mm. I’ve posted some pictures of all of them at the end of these notes.

The Pentax is largest of the bunch but does not weigh quite as much as you would expect at 390 grams. It handles very well, helped by the large and nicely contoured rubberised upper body. The large, screw-up rubberised eyecup ( with 15mm travel approx) works very smoothly and is genuinely useful for eye positioning. The Pentax’s huge eye lens (34mm in diameter !) is very accommodating to the eye and immersive making the XW’s 70 degrees seem even wider. In use the field of view does not look much, if any, less than the Nagler’s 82 degrees. The Pentax has JIS Class 4 weatherproof construction (shower proof ?). It uses 7 lens elements, has 20mm of eye relief, a 70 degree apparent field of view and retails for £270.00.

The 7mm Baader Genuine Ortho seems tiny by comparison to Pentax and Naglers. It’s compact and light but very well made and finished. The Baader has no safety undercut machined into it’s chrome barrel, which some may prefer. The eyepiece has a tiny, 5mm diameter, eye lens and no eye cup. The apparent field of view is 40 degrees or so and the eye relief is around 5mm, which is normal for the orthoscopic design. The Baader is very nicely finished, including a really well internally blackened and ribbed barrel to minimise stray light. It uses the classic orthoscopic optical design which has 4 lens elements. The Baader also uses the purple-sheened and enticingly named “Phantom” multi-coatings on all glass-to-air lens surfaces and they retail for around £75.00 each.

The Tele Vue Nagler Type 6’s seem also to be of top quality construction to me. Their optics have deep green coatings. The Nagler’s eye lens is 18mm in diameter and the eye relief provided is 12mm. The fitted rubber eyecup is quite stiff but does fold down if needed. All the T6’s are around the same size as a standard 32mm plossl. As with other Naglers, an 82 degree apparent field of view is provided. T6’s use 7 lens elements, weigh around 240 grams and retail for around £210.00 each.

I’ve been struggling quite a bit to think of how to compare the performance of these eyepieces in these notes.

I have used them quite a bit lately on a variety of subjects, combined with either a 10" F/4.8 newtonian or a 6" F/8 refractor. Targets included the Moon, Mars, Saturn, double stars and some popular deep sky objects. Setting aside the physical characteristics of the eyepieces and the field of view differences, I have found their optical performance to be more or less equal – in a word excellent. Any differences between them are extremely subtle.

There have been circumstances when the larger field of view of the Pentax and Naglers has made finding an object and keeping it in the field of view a little easier but I can honestly say that there is nothing that I have seen in one eyepiece that could not be seen more or less equally as well in one of the others. All these eyepieces show stars as pinpoints to the edge of the field of view, even in my F/4.8 Newtonian – any coma showing there originated with the scope, not the eyepieces.

There was one exception to the above though. One evening when the seeing was good and Saturn was well placed. I was counting the number of Saturnian moons that I could pick up with my 10” Newtonian and got 6 – including the faint Enceladus. On that occasion I found that the fainter moons stood out a little more readily with the Pentax XW. The XW reminds me in fact of the superb performance of the Tele Vue Ethos in this respect. With the other eyepieces I could see these faint moons as well of course, but the Pentax just seemed to make it a touch easier to pick them out of my moderately light polluted skies.

While comparing these eyepieces I also took the opportunity to look for any “tint” that an eyepiece was adding to the view – an issue often discussed in relation to Tele Vue eyepieces. Obviously I can only report how my eyes (eye !) saw things but any variation in colour, if there at all, was very, very subtle indeed. I may have detected a faint “warmer” tone on the lunar surface when using the Naglers and possibly the Pentax could have been described as presenting a slightly “colder” view. But all very subtle as I said.

In terms of viewing ease and comfort, the Pentax leads with its large eye lens, generous eye relief and great ergonomics. The Naglers are fine to use as well but I’ve been using that eyepiece type for sometime now so I’m probably accustomed to the optimum eye positioning to see the full field of view. The Baader GO is quite practical but does take some practice in getting your eye close enough to the tiny eye lens so, for me at any rate, it’s not quite as pleasant experience as using the Pentax and Tele Vue’s is.

So which is best ?. Wow that’s a real tough question to answer !.

In value for money terms the Baader Genuine Ortho is the clear winner – top class performance for 1/3 the price of the other brands I’ve been describing here. If the short eye relief and narrower field of view is OK for you then you can’t go wrong with these.

Traditional views would hold that the Pentax and Naglers had no right to be performing anywhere near as well as the orthoscopic design because of their additional lens elements – and yet, to me at least, they were fully as sharp and contrasty as the simpler design but with the benefit of the longer eye relief and wide fields of view. I guess that modern glass types, superb multi-coatings and excellent internal light suppression have eroded the performance edge that the simpler designs used to have although the Baader has these qualities as well of course.

I really like the Tele Vue Nagler range and the Type 6’s are great medium to high power eyepieces with sharp, ultra-wide fields of view. In the Pentax XW 10mm though the 9mm certainly has an equal and, in some circumstances I believe it’s possible that the Pentax will exceed the Tele Vue a touch.

If you have the budget, and assuming that the 7mm and 5mm version match the 10mm in performance, Pentax XW’s would make superbly capable medium to high power eyepiece set I feel.

Many thanks to First Light Optics for the loan of the Pentax and the Baader eyepieces – it’s a real privilege to be able to try out these great eyepieces and a lot of fun as well :(





Edited by John
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John a very interesting and enjoyable review of these medium power EPs. Yesterday I bought my first Nagler which is a second hand 5mm. I hope to be testing this EP over the next few weeks.

If we have the chance it will nice to talk further at SGL5 and we meet up again.

Best regards


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Great review John. I really want one of those Pentax XW's. Had the XL's and they were yum, so the XW must be mega yum.

I've had my fill of Orthos for a while. In the last year i have had a 6mm Antares, 7mm Baader, 10.5mm Meade RG and 12.5mm UO. But just can't get on with the tight field and limited ER of the short focal length models. I should be embracing them in my financially challenged position but i have chosen a cheap SW 6mm UWA over a UO 6mm Ortho.


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Excellent report, your description of the Baader GOs tiny eye lens and how close you need to be to it reminds me of the teeny EPs I have for my Prinz, where I almost have to touch the EP with my eye to get a view (6mm).

I hope I can write something remotely as informative when I finally get to play with my new toys.

I suppose you have to give them back now, do you?

Edited by yeti monster
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What a spiffing report, John. You put everything so well and honestly.

The Pentax looks and sounds like a really pleasant eyepiece to use. I don't usually observe with my glasses, but if I did, money no object my eyepiece case would definitely be filled with XWs. They sound truly delicious.

I was relieved to hear the more complex eyepieces holding up against the ortho :D

Well done - great review :(


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Thanks for the comments folks :(

The small eye lens and short eye relief are quite normal features of ortho eyepieces - on eye relief I think they are a little better than equivilent focal length plossls. The Baader GO is an excellent example of the ortho type - the best available at an affordable cost IMHO :D

..I suppose you have to give them back now, do you?

Yep - unfortunately :)

Very decent of First Light Optics to lend them though - much appreciated :D

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Excellent and honest review there John.

Eyepieces are very difficult to test as everything really depends on the preferences of the observer. You have done a great job of including all the relevant information which really makes it easier to 'visualise' how each eyepiece may suit me the reader.

I have not used the 7mm ortho but having used several of it's brethren I have a good idea of it's performance. I totally agree that observing comfort is an important consideration. Also I too find that not all 'multi-element' eyepieces loose out to simpler designs.

Thanks for you your hard work in writing this up and, perhaps more importantly,


Edited by part timer
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  • 3 weeks later...
Thanks John, that was a very interesting review and really informative!

Hopefully in the future i will be able to afford an ep of this quality!

The Baader Genuine Ortho's are quite affordable IMHO and even more so used. when you can ge them for less than £50 each - quite a bargain for premium peformance.

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