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Old 09-09-2019, 05:43 PM
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Pentax XW eyepieces versus Naglers

Anyone had experience with both?

The XW10mm seems to get the most praise from my short research.

I am looking at a 3.5 or 5mm. Perhaps a 20mm later.

The Nagler 22mm Type 4 though is a classic eyepiece.

Greg.
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Old 09-09-2019, 06:54 PM
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It depends on the scope they’re used with. They were designed for Pentax refractors which are long out of production.

The Naglers tend to fare better in newtonians but the XW are (mostly) excellent in refractors and compound scopes. I’ve never used a 22mm Nagler but have the 20T5 and it is sharp in every scope I’ve tried it. I used to have the 13T6 (great little eyepiece) and several Ethos. When I got more into imaging I sold them and kept the XW.

I’m probably more invested than most as I have the full set. When the sky is good for my scopes, the 10 and below are great. The 14 and 20 are good in an SCT, and the 30 and 40 are my goto eyepieces in my Edge 11. They’re my keep set, but everyone’s eyes and opinions are different.

Some find they experience blackouts with some of the XWs, but I find if you wind the shaft out it eliminates it. I prefer the mechanism of the XWs compared to the Delos (for example), and find the eye relief very comfortable once you master the wind out cover. The Ethos have little eye relief by comparison, maybe by necessity.
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Old 09-09-2019, 07:48 PM
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Originally Posted by Camelopardalis View Post
It depends on the scope they’re used with. They were designed for Pentax refractors which are long out of production.

The Naglers tend to fare better in newtonians but the XW are (mostly) excellent in refractors and compound scopes. I’ve never used a 22mm Nagler but have the 20T5 and it is sharp in every scope I’ve tried it. I used to have the 13T6 (great little eyepiece) and several Ethos. When I got more into imaging I sold them and kept the XW.

I’m probably more invested than most as I have the full set. When the sky is good for my scopes, the 10 and below are great. The 14 and 20 are good in an SCT, and the 30 and 40 are my goto eyepieces in my Edge 11. They’re my keep set, but everyone’s eyes and opinions are different.

Some find they experience blackouts with some of the XWs, but I find if you wind the shaft out it eliminates it. I prefer the mechanism of the XWs compared to the Delos (for example), and find the eye relief very comfortable once you master the wind out cover. The Ethos have little eye relief by comparison, maybe by necessity.
Thanks for the very informative reply. I think I'll have to get at least one for now and see how I like it. I've been hearing about them for ages.

Greg.
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Old 09-09-2019, 09:06 PM
JoeBlow
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I have the 10, 7 and 3.5 XW. They are every bit as good or even slightly better than Naglers. Not only do they have excellent eye relief, but I personally find them much easier to find and hold the exit pupil, compared to Televue eyepieces, including Naglers, that can be fussy on eye placement. The main advantage Naglers have over the XWs is their big 82 degree field. But note, the 20 and 14 XW are reported to have field curvature, so I recommend a Nagler or another type in this focal range.

So if it was me, I would purchase a 5 or 3.5 XW and then the 22 T4 Nagler.
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Old 10-09-2019, 05:04 AM
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I am a fan of both Pentax and Televue and have several of both. I use them in Reflectors and Refractors and they do well in both.

When in the mood/need of wide views, the Televue Naglers and Ethoi are hard to beat. When it comes time to pump up the magnification I like the Pentax. I have the XWs 3.5, 5, 7 and. 10 and believe them to be wonderful. Easy to look through (I like their mechanism for eye-placement) a nice flat, sharp “cool” view. Ample eye relief.

The Televue lines to me are a little pickier on eye-placement and not as much eye relief. The Ethos line has the “cool” view I like (similar to the Pentax) but with a wider field...I have the 4.7, 13 and 21 I prefer the Pentax view over the shorter Ethos but the wide field is great when looking for faint fuzzies. I also have a number of Naglers, big fan of the 31 like looking through a portal and 16 (tight eye relief) but sharp sharp sharp. The Nagler views have a warmer tone to my eye...

Can not go far wrong with either...at least in the USA the Pentax XWs are on sale at the moment.
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Old 10-09-2019, 05:16 AM
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Originally Posted by JoeBlow View Post
I have the 10, 7 and 3.5 XW. They are every bit as good or even slightly better than Naglers. Not only do they have excellent eye relief, but I personally find them much easier to find and hold the exit pupil, compared to Televue eyepieces, including Naglers, that can be fussy on eye placement. The main advantage Naglers have over the XWs is their big 82 degree field. But note, the 20 and 14 XW are reported to have field curvature, so I recommend a Nagler or another type in this focal range.

So if it was me, I would purchase a 5 or 3.5 XW and then the 22 T4 Nagler.
Thanks for that advice. That's what I was thinking as well.

Greg.
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Old 10-09-2019, 12:50 PM
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Due to what Duncan said regarding these eyepieces being designed for telescopes that are no longer in production, they are not all effective in each type of telescopes or a broad range like Naglers are.

If I remember correctly. The 10mm XW and shorter focal lengths were rather well corrected in even sub-F5 reflectors but the 14mm and above induced heavy field curvature. I remember testing this myself a couple years back. I couldn't stand them in my 12" without a coma corrector/field flatterer.

I tested the 14, 20, 30 and 40mm and they were bloody awful without a corrector. And only passable with it. If you want a 14mm with essentially the same ergonomics, fov and image quality as a Pentax get a Delos 14mm instead.

Should be good in your refractor though.
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Old 10-09-2019, 03:47 PM
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Quote:
Originally Posted by AG Hybrid View Post
Due to what Duncan said regarding these eyepieces being designed for telescopes that are no longer in production, they are not all effective in each type of telescopes or a broad range like Naglers are.

If I remember correctly. The 10mm XW and shorter focal lengths were rather well corrected in even sub-F5 reflectors but the 14mm and above induced heavy field curvature. I remember testing this myself a couple years back. I couldn't stand them in my 12" without a coma corrector/field flatterer.

I tested the 14, 20, 30 and 40mm and they were bloody awful without a corrector. And only passable with it. If you want a 14mm with essentially the same ergonomics, fov and image quality as a Pentax get a Delos 14mm instead.

Should be good in your refractor though.
Thanks for that write up most helpful. I'll stick to the shorter lengths.

I am also considering a Stellarvue Optimus 3.7mm which is 110 degree but large and heavy. I have had a 13mm Ethos before. It was very good. Much like a Nagler only very large and heavy plus quite expensive.

Greg.

Greg.
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Old 10-09-2019, 05:54 PM
Hans Tucker (Hans)
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One thing I have learnt .. eyepieces are a personal choice. What maybe the ducks guts for one person may be a dud to another. I have used the XW's (5, 7, 10 and 20) I didn't really like them.
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Old 10-09-2019, 08:23 PM
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Quote:
Originally Posted by AG Hybrid View Post
Due to what Duncan said regarding these eyepieces being designed for telescopes that are no longer in production, they are not all effective in each type of telescopes or a broad range like Naglers are.

If I remember correctly. The 10mm XW and shorter focal lengths were rather well corrected in even sub-F5 reflectors but the 14mm and above induced heavy field curvature. I remember testing this myself a couple years back. I couldn't stand them in my 12" without a coma corrector/field flatterer.

I tested the 14, 20, 30 and 40mm and they were bloody awful without a corrector. And only passable with it. If you want a 14mm with essentially the same ergonomics, fov and image quality as a Pentax get a Delos 14mm instead.

Should be good in your refractor though.
I used to have the plots that Pentax published, but IIRC the field curvature of the EPs 14+ differs from those <=10mm. This may explain their behaviour in refractors/SCTs vs newts.
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Old 11-09-2019, 05:43 PM
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One thing I have learnt .. eyepieces are a personal choice. What maybe the ducks guts for one person may be a dud to another. I have used the XW's (5, 7, 10 and 20) I didn't really like them.
Was it you wanted a wider field of view or something else?

Greg.
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Old 11-09-2019, 07:39 PM
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Originally Posted by gregbradley View Post
Was it you wanted a wider field of view or something else?

Greg.
I chose the XW's because I wanted to try widefield eyepieces and they received good reviews. I have tried a couple of the TeleVue Ethos (10 & 13) and I am looking at trying the Nikon NAV series and Tak UW series. I found that I didn't sell my XW 7mm so if you want to loan it to try it out it wont be a problem.
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Old 13-09-2019, 04:00 AM
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The 10mm, 7mm, 5mm, and 3.5mm all have negative field curvature.
The 14mm, 20mm, 30mm, and 40mm all have positive field curvature.
It depends whether that matches your scope as to whether you see a flat field or not.
Here are the astigmatism/FC curve graphs:
https://web.archive.org/web/20150522.../xo-xw/64.html
If the two curves (sagittal and meridional) deviate, that indicates astigmatism. The center of the field is at the bottom and the edge is at the top. The scale is in diopters (the eye can usually accommodate 1, but 2 would be seen as curved).
Ideally, the two curves would not deviate and they would be vertical.

The 30mm and 40mm have been out of production a long time, but are coming back soon--perhaps by the end of the year.
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Old 13-09-2019, 06:41 PM
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Quote:
Originally Posted by gregbradley View Post
Anyone had experience with both?

The XW10mm seems to get the most praise from my short research.

I am looking at a 3.5 or 5mm. Perhaps a 20mm later.

The Nagler 22mm Type 4 though is a classic eyepiece.

Greg.
I own all of the 1.25" Pentax XW's and 19 different Televue eyepieces including all of the Nagler T4's. I also own the 31mm T5, and several ETHOS, DELOS, Radians and Panoptics.

In focal lengths 10mm and less my preference is for the Pentax XW's. The 3.5mm, 5mm, 7mm and 10mm Pentax XW's are exceptional eyepieces and provide excellent flat field views in ALL TELESCOPE TYPES, including Refractors and Newtonians. I prefer the eye guard adjustment over the various eye guard systems used by Televue, although I will say the eye guard system on the DELOS is a monumental improvement over the instadrop system on the Nagler T4's and the Radians.

In focal lengths over 10mm I like the DELOS and the Nagler T4's. Although in a fast Newtonian the Nagler T4's really need a paracorr. If you don't need long eye relief the Nagler T6's are excellent. Above 20mm I like the 26mm and 31mm Nagler T5's and the 27mm and 35mm Televue Panoptics.

If money is no object the 17mm and 12.5mm Nikon NAV HW are currently the best eyepieces money can buy. They have performed exceptionally in every telescope I have used them in. The 12.5mm Doctor is also excellent, but again a lot of money.

Cheers
John B
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Old 13-09-2019, 07:31 PM
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wow, some fantastic responses here. Some very knowledgeable and experienced visual astronomers know their stuff.

Thanks.

Greg.
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Old 14-09-2019, 07:39 PM
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Greg late addition here but..I have Tak Abbes ans Delites which I love by far..might want to read this compared to Pentax xw or Deloi which I also own/owned and use.
https://astronomyconnect.com/forums/...ight-review.1/

Bigjoe

Last edited by bigjoe; 14-09-2019 at 07:53 PM.
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Old 15-09-2019, 12:43 PM
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Most helpful, thanks BigJoe.

Greg.
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Old 15-09-2019, 01:42 PM
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I have had and do own a couple of XW s 10 /5 mm might get a 3.5 one day , as mentioned above extending the eyeguard to the sweet spot that suites you makes these eyepieces extremely comfortable to use .


I also had the 14mm for quite a while and found it really good despite the bad press it gets .


The other longer lengths I dont have experiance with , I do recall the 30 and 40 mm being not overly popular on some performance issues ? and ( they were pricey) then you you couldn't buy them anymore and people forget .

Last edited by GrahamL; 15-09-2019 at 01:55 PM.
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Old 15-09-2019, 09:22 PM
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In the US the Pentax XW are on sale at $269...I believe this to be a really good price for an excellent eyepiece line (3.5mm to 10mm).

I do not know how long the sale lasts but if I did not already own them I would be buying.
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Old 16-09-2019, 12:16 AM
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Quote:
Originally Posted by Don Pensack View Post
Here are the astigmatism/FC curve graphs:
https://web.archive.org/web/20150522.../xo-xw/64.html
.
Its a pity all manufacturers dont publish these. *Do any other manufacturers publish this data?

It's also interesting to note, that
1) if it is indeed true that different types of telescopes have different focal plane curvature, that...
2) must be matched to the curvature of the eyepiece used, then...
3) given that the XW's were originally designed for the pentax spotting scopes,
4) half of the range must have been not fit for purpose, by design.

Which doesnt seem right to me. Given the luxury of custom designing high quality eyepieces to suit a particular telescope, why would they design half their range 'wrong' for that purpose? It doesnt make sense.

Markus
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