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Torn on 7mm

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#1 wxcloud

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Posted 29 April 2022 - 12:18 AM

Think I've finally decided on the next focal length eyepiece. I just don't know which to get. Basically up between the Pentax xw (heck of a time to decide since they are nearing end of sale) and a nagler. Another mention would be the Astronomics 100° which best the other two on price. Skies are bortle 8 / 9 but I've managed some globs with an AT80EDT.

How the heck do you pick? The nagler gives a wider afov but short on eye relief. I've found the 13mm t6 a little "hard" but it's usable. The 82° might require a coma corrector for the dob. The nagler is also lighter and smaller of the other 2 possible 7mm eyepieces.

#2 havasman

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Posted 29 April 2022 - 12:49 AM

I've never used an XW but everybody that does seems to love 'em. I'm a big T6 fan but I skip from 13 to 5mm so I don't know about the 7. It's probably swell like the rest. I really do think they're all the eyepiece performance I can possibly require. The APM HDC 7mm is really very good. Surprisingly good and I sold a 13E to keep the 13 HDC. But if the A-T XWA's had been announced when I bought the APM's I'd have waited and would have the A-T's.

 

Anyway, you have only great choices. Congratulations!


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#3 betacygni

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Posted 29 April 2022 - 02:47 AM

If you find the t6 eye relief even slightly uncomfortable, I’d pass on the nagler. Depending on scope at 7mm you’re sneaking up on planetary mags, and in my opinion comfort trumps all here (and in fact with most observing). The more comfortable you are the longer you will look, and the more you will see, and you’ll be there for momentary better seeing.

All that said I’d split the different and go with a Morpheus, wider than the XW, and very generous eye relief.
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#4 Jon Isaacs

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Posted 29 April 2022 - 03:01 AM

I've never used an XW but everybody that does seems to love 'em. I'm a big T6 fan but I skip from 13 to 5mm so I don't know about the 7. It's probably swell like the rest. I really do think they're all the eyepiece performance I can possibly require. The APM HDC 7mm is really very good. Surprisingly good and I sold a 13E to keep the 13 HDC. But if the A-T XWA's had been announced when I bought the APM's I'd have waited and would have the A-T's. Almost certainly the same level of performance and from a much better company and set of folks.

 

Oops, I said that right out loud didn't I...

 

Anyway, you have only great choices. Congratulations!

 

I have all the T-6 Naglers except the 2.5 mm.  They are all very similar, both mechanically and optically. They're compact eyepieces with sufficient eye relief for me. They fit my eye socket very nicely. Optically they're very sharp both on axis and off-axis.  

 

But I also agree with Dick, the 7 mm Astro-Tech XWA would be very tempting. I have the 8 mm Ethos and the 100° view is very nice. There should be more eye relief than the Nagler and at $250, the price is right. 

 

Jon



#5 Avgvstvs

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Posted 29 April 2022 - 03:06 AM

The fact that you mention "nagler' a few times in your second paragraph, indicates that you have already decided IMHO..lol. Eye relief is always a safe choice so i would go the Pentax XW. Not as exotic, but a proven performer. Otherwise pick based on AFOW.



#6 izar187

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Posted 29 April 2022 - 03:27 AM

Perhaps consider a 7mm Siebert Ultra.

https://siebertoptic...eces-ultra.html

 

I very much prefer mine over my former 6.7mm UWA Meade, after comparing them side by side.

Optically and ergonomically.

Wide field with very comfy eye relief beats wider field with short eye relief. For me.



#7 luxo II

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Posted 29 April 2022 - 06:54 AM

How the heck do you pick? 

Well, you decide what the “wants” are, and prioritise them according to what matters most to you - “pairwise comparisons” help. 
 

Image quality - sharpness and contrast (ghosts, scattered light, flare etc) ?

Wide (ultra) field of view ?

Eye-relief ?

 

You can  have any one of these, but not all three. In my scope  7mm is high power (420X) and it’s all about image quality. The rest are irrelevant. 
 

have been hoping to find a 7mm SMC for years, but finally settled for a Nikon 7mm ortho.

 


Edited by luxo II, 29 April 2022 - 06:57 AM.


#8 Chad7531

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Posted 29 April 2022 - 07:23 AM

If you desire a nice comfortable EP with long eye relief that just works I’d get the XW. If you want a wider view than 70 degrees go with something else, although the XW feels wider than it is. I’m an xw guy and would pick it every time. The 7mm is great, they all are.

Edited by Chad7531, 29 April 2022 - 07:24 AM.

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#9 sw196060

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Posted 29 April 2022 - 08:45 AM

I have found that for exit pupils below 2mm I don't need to wear my glasses so, actually prefer taking glasses off when

viewing at higher mag.   I feel I get a cleaner view without my eyeglasses in the way.   For this reason, I don't need longer eye relief.

For me, I therefore found the Nagler T6s were easy to use < 13mm.  At 13mm, not so much.

This may be a consideration for you.


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#10 iseegeorgesstar

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Posted 29 April 2022 - 09:14 AM

Think I've finally decided on the next focal length eyepiece. I just don't know which to get. Basically up between the Pentax xw (heck of a time to decide since they are nearing end of sale) and a nagler. Another mention would be the Astronomics 100° which best the other two on price. Skies are bortle 8 / 9 but I've managed some globs with an AT80EDT.

How the heck do you pick? The nagler gives a wider afov but short on eye relief. I've found the 13mm t6 a little "hard" but it's usable. The 82° might require a coma corrector for the dob. The nagler is also lighter and smaller of the other 2 possible 7mm eyepieces.

 

If the sale ended would you still get the pentax? If the nagler magically ceased production would be upset you didnt get it or just get over it because you secretly wanted another EP? 

 

Whats your gut telling you?


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#11 CrazyPanda

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Posted 29 April 2022 - 09:23 AM

I tend to agree with betacygni - comfort is important to noticing details.

 

If you find your 13 T6 a bit hard due to eye relief, you'll find the 7mm Astro-Tech XWA even harder.

 

The 7mm Astro-Tech claims 15mm of eye relief, but the same eyepiece from APM claims just 13mm: https://luntsolarsys...m-100-eyepiece/

 

I would tend to believe the APM figure is more accurate. I find the 15mm of eye relief on the 8 Ethos to be tight for that apparent field of view, so 13mm from the 7 XWA would be worse, and you may find is hard or harder than the 13 T6. I don't own a 13 T6 but I did spend some time looking through one at a club outing and I find it surprisingly comfortable - more so than the 8 Ethos. 12mm of eye relief @ 82 degrees seems more comfortable to me than 15mm of eye relief @ 100 degrees.

 

That means that if you consider 12mm @ 82 degrees to be "hard", then 13mm @ 100 degrees will be even harder - doubly so since the eye lens housing around the 7 XWA is so much larger than the Nagler's making it even more challenging to fit it into your eye socket. So that 13mm of eye relief on paper is probably proportionally less *effective* eye relief than the 12mm paper value of the Nagler. So I would pass on the 7 Astro-Tech in your case.

 

That leaves 6.5 Morph, 7 Pentax XW, 7 Nagler, and 7 Nikon NAV-SW.

 

I really, really enjoy my 7 Pentax XW and find I reach for it more often than the 6 and 8 ethos for deep sky and definitely more than those ethos for lunar (I really dislike hyperwides on the Moon). I have not had an opportunity to put it through its paces on planetary views yet.


Edited by CrazyPanda, 29 April 2022 - 09:25 AM.


#12 rustynpp

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Posted 29 April 2022 - 10:09 AM

If you find your 13 T6 a bit hard due to eye relief, you'll find the 7mm Astro-Tech XWA even harder.

Not necessarily. While I haven't used the 7 XWA, I find the 13 XWA to be more comfortable than the 13 Nagler. Using the 13 XWA feels completely natural to my eyes, whereas the 13 Nagler is still comfortable but takes somewhat more effort. I definitely feel more immersed and at-ease with the XWA.

 

Of course, YMMV.

 

Cheers,

Nick


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#13 vahe

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Posted 29 April 2022 - 10:24 AM

 

have been hoping to find a 7mm SMC for years, but finally settled for a Nikon 7mm ortho.

 

One was offered in the classifieds here, Pentax 7mm SMC Ortho, price $315.00 and sold almost instantly. I have a pair that I use with my 155 F9 APO, these are the finest planetary eyepieces that I have encountered, very sharp with exceptionally low scatter.

.

Finding one is not going to be easy but finding a matched pair, good luck !!!!!

.

Vahe



#14 wxcloud

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Posted 29 April 2022 - 02:07 PM

Welp, went for the penny:

Wanted to try one
Figured it would work best across my scope collection
Eye relief
Seemed to be fairly decently regarded everywhere.

#15 Dave Mitsky

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Posted 29 April 2022 - 02:55 PM

I own a 7mm Pentax XW and a 7mm Tele Vue T6 and prefer using the 7mm Pentax XW, despite its smaller AFOV.


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#16 GeneT

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Posted 29 April 2022 - 02:57 PM

I don't have any ethnical analysis for this comment, but I did not like the 7 Nagler (I loved many of their other focal length eyepieces.) However, I loved my 7 Pentax XW.



#17 Dave Mitsky

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Posted 29 April 2022 - 03:00 PM

I haven't had any eye relief issues with my recently purchased 9mm A-T XWA so far. 



#18 Tarantular

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Posted 29 April 2022 - 04:41 PM

I also have the Pentax 7mm XW. Its a great EP, however, i dont like that if you look at it off center bit, it blacks out. My other 11-14mm EP 82 FOV dont have this issue and i can look at them at a slight angle.



#19 wxcloud

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Posted 29 April 2022 - 07:29 PM

I also have the Pentax 7mm XW. Its a great EP, however, i dont like that if you look at it off center bit, it blacks out. My other 11-14mm EP 82 FOV dont have this issue and i can look at them at a slight angle.


Oh! That was the other reason I was checking other eyepieces out as well because I read eye placement was a little tricky and potential field curvature. Oh well, it's on its way now. If I don't like it, there's others to try :)

#20 jrazz

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Posted 29 April 2022 - 07:52 PM

As someone who had experienced eye placement issues on my Pentax I can tell you that it's probably user error. It was on my end. Once I figured out how to screw the eyecups out I have had no darkening whatsoever. You do need to screw them out quite a bit if you don't wear glasses since the eye relief is substantial. This is the case for my Lasik corrected eyes in any case. YMMV

 

As far as field curvature goes, I can't say I see any. To my eyes at least the field looks near as makes no difference to perfect. (referring to Pentax SMC-XW 10mm, 7mm, 5mm)


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#21 Chad7531

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Posted 29 April 2022 - 08:02 PM

None of the 1.25” XWs give me that issue. It was a big surprise to me too because I had multiple EPs of different makes and models that did before I switched to XWs exclusively. And they’re all excellent.
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#22 GGK

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Posted 29 April 2022 - 08:08 PM

I would probably buy all three used and sell the two I didn’t like as much if I could only keep one.

The problem is that I would want two of them - the AT 100 degree for when I want the wide field, and the XW 70 degree with the long eye relief to use when I wanted a narrower field or when I was tired and wanted the comfort of the long eye relief.

But it’s possible that the 82 degree Nagler might give a better image in my scope with my eyes than one or both of the other two. So, see if there is a way to try them first.

#23 Chad7531

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Posted 29 April 2022 - 08:09 PM

I really wish I kept my XF 8.5mm. Tack sharp, just as easy or easier to use than the XWs, put it in a TV 2x Barlow and it behaves exactly the same. It’s sharper than the XWs and $130. Just narrow FOV.

#24 CrazyPanda

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Posted 29 April 2022 - 09:15 PM

Oh! That was the other reason I was checking other eyepieces out as well because I read eye placement was a little tricky and potential field curvature. Oh well, it's on its way now. If I don't like it, there's others to try smile.gif

I believe only the 14 and 20 have significant field curvature. I see no FC in my 7XW and as long as the eye guard is set to the right distance, the eyepiece is very comfortable. Even without the eye guard set precisely, I've found it quite forgiving. However, if the eye guard is set too low, I do see kidney beaning on the Moon with it (same with the 10mm). So to avoid kidney beaning on the Moon, you have to raise the eye cup a bit more than you might find is necessary for deep sky viewing with it. It's still quite comfortable regardless.


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#25 turtle86

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Posted 29 April 2022 - 09:55 PM

Think I've finally decided on the next focal length eyepiece. I just don't know which to get. Basically up between the Pentax xw (heck of a time to decide since they are nearing end of sale) and a nagler. Another mention would be the Astronomics 100° which best the other two on price. Skies are bortle 8 / 9 but I've managed some globs with an AT80EDT.

How the heck do you pick? The nagler gives a wider afov but short on eye relief. I've found the 13mm t6 a little "hard" but it's usable. The 82° might require a coma corrector for the dob. The nagler is also lighter and smaller of the other 2 possible 7mm eyepieces.

 

Tough call!  Both are excellent.

 

I have the 7mm Nagler T6 myself and it's superb; very sharp on and off axis.  I had some splendid views of M3 with it in my 12.5" Dob this week. The stars were beautifully resolved, like tiny diamonds on velvet.  I also like how it packs a large, sharp FOV into a compact package.  

 

The only potential issue with the 7mm Nagler T6 is the eye relief.  I personally find it amply comfortable but you might not, based on your experience with the 13.  

 

I've looked through a 7mm Pentax XW a few times and found it to be very comfortable.  It might be a better choice if you want (or need) more eye relief than what the Nagler provides.


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