Televue Nagler 31mm

[pvaz]

Right after sunset, when the moon was still just appearing in the horizon, I took a quick look at the Orion Nebula, Double Cluster and NGC457.

The 1st thing I noticed on the Nagler, besides it's enormous size, was the blackouts! I think the proper name for this is kidney beans. It shows a dark area, shaped as a kidney, that appears on the surface of the lens. After splashing this kind of cash on an EP that's not a good start!

After I calmed down, I toke my time to "learn" how to look through it. I found that I couldn't tilt my face to the side as I usually do with most EPs. To see a proper image I have to keep my head straight, with the tip of my nose touching the side of the volcano top. Any closer and I get black instead of stars.

Ok, after the initial shock I focused on M42 and pulled it to the edges of the FOV. Focus is sharp edge to edge with every object getting focused at the same time as you play with the focuser. The objects do stretch a bit when they reach the edge of the FOV as explained by Al Nagler as a physics limitation needed to have a flat field with this AFOV.

The image looked very good! Then I put the bigbarlow 2x in with the Nagler to scan the trapezium. This made it show kidney beans sooner! I had to keep my eye a bit more away from the rubber cup as the combination seamed to have an increased eye-relief. After placing the eye correctly, the view was still amazing and I couldn't see any loss in detail caused by the extra glass.

On the double cluster and NGC457 the idea was the same: Great views, quality image and pinpoint stars from edge to edge!

Conclusion: Although the sky was far from ideal for DSO observation due to a very bright moon, I could tell the image on the Nagler is much better then my old budget wide field EP. That said the demands on how I have to place my head to avoid the blackouts ware annoying and I'm not very pleased with it, at least when I think of the cost of this EP.

I'll be using it for a while as I need some dark skies to properly test it but there is a great chance I'll resell it and get a Panoptics 35mm or Pentax 30mm instead. It all depends whether I can adapt to it or not.

[AndyH]

Nicely written Paulo.

I have to admit, when it comes to eyepiece abberations, the kidney bean/blackout effect, is one that annoys me greatly. I can put up with pincushioning and the rest, but not that for some reason.

I would continue to try it out and see if you can get used to positioning your head. After all, you've shelled out a lot of money for it.

Cheers,

Andy.

[pvaz]

Yeah I hope it becomes second nature. I did enjoy the views but it seamed like a bit of hard work as I'm addicted to that head tilt!

[John]

I've had a Nagler 31mm for around a year now. They do take some getting used to but I have say I've not experienced the "blackouts" you describe personally.

During the summer and autumn last year I had the chance to borrow a Skywatcher Nirvana and a Pentax XW30 - I've posted a review of the 3 in the "reviews" section. The Nirvana performed very much like the Nagler 31 and I found I had to adopt an unfamilliar head position with it because of the very wide eye cup (almost a face cup !). The Pentax was excellent and probably the easier of the 3 to look though - the edges of the FoV are easier to see without head tilting because it's narrower than the Nagler and Nirvana, but still a healthy 70 degrees. I'm a sucker for the ultra-wide FoV though so I'm happy to perfect the technique of using the Nagler - the views of the Veil Nebula with an OIII filter and my 4" F/6.5 ED Vixen are stunning !

I'd give the big Nagler some time and see how you like it then. If you do decide to sell at least you will have no trouble shifting it !.

[pvaz]

I live in a very dark area, but there's just the one street light close to my favorite observation spot. To avoid it's light I'm used to tilt my head and stick my eyeball inside the eye guard rubber. It's when I do that on the Nagler that it blacks out.

John, if you don't mind, can you try this "Technic" on yours just to confirm if you get the same problem or not?

[John]

I live in a very dark area, but there's just the one street light close to my favorite observation spot. To avoid it's light I'm used to tilt my head and stick my eyeball inside the eye guard rubber. It's when I do that on the Nagler that it blacks out.

John, if you don't mind, can you try this "Technic" on yours just to confirm if you get the same problem or not?

Sure Paulo, I'll give it a try and report back

[arad85]

I must be a natural with the Nagler - I don't get kidney beaning at all... Funnily enough, the one eyepiece I did experience it with was a 14mm Pentax XW - supposedly something that doesn't exist with that eyepiece! The 31mm is a cracking eyepiece - keep with it Paulo....

[Merlin66]

Re annoying light.

I have a "black out" curtain. Like the old fashioned photographers used. About 2' square black cloth.

It fits around the focuser and drapes over your head... cuts out all the extraneous light. Very handy.

Ken

[TakMan]

Used the 31mm last night at my mates place in his 16" Lightbridge and my Tak TSA102s (on an EZTouch mount) without any of the 'problems' you describe - and we were out a good 3-4 hours...

We still love this eyepiece, even though I now also have the full range of Ethos - including the 21mm (TH are doing the 10% offer - and early, if you ask! - as a good customer - I've had mine for a week!)

We were out looking at the Double Cluster also, doing comparisons with the Moonfish eyepiece, and both with and without my newly purchased Televue Paracorr (also 10% off) - will report back later on that!

Damian

[pvaz]

Damian, can you check if you place the eyeball inside the rubber guards (head tilted to the left when looking with the right eye) do you still see an image without blackouts?

I did read some reviews that reported this blackout when you stick you eye in to take in the entire FOV:

Astromart Reviews - Review of the Televue Nagler 31mm, T5

31mm Nagler Type 5 (2nd review)

Televue Nagler 31mm - Telescope Eyepiece Reviews

I suspect I just need to correct my observing technic, but I want to confirm if you see the same just to rule out a possible faulty EP. I don't think thats the case as it showed perfect images when the eye was placed correctly but better safe then sorrow as it's under warranty and I can have it sent to Televue.

[michael.h.f.wilkinson]

Kidney-beaning is a real pain sometimes, and can put off guests viewing through your telescope. I have just got the 22mm T4, and it does not show very much kidney-beaning. The TMB Paragon 40mm has got it beaten on that front however (also on pincushioning, but then it has "only" a 69deg AFOV)

[TakMan]

Pvaz - I asked my observing buddy to clarify, and we both came to the same conclusion that we straight align our right eye to the eyepiece lens... with the rubber eye guard just brushing the side of the nose, so I suppose our eye would be just inside the eye guard.

I personally find then that I can rotate my eye in it's socket around the entire field without any blackouts.... With the Ethos, I do rotate my head as well slightly as I find it too painful to strain my eye to the field of view... and again, no real blackouts either....

I'd give it a few more goes first to see if you can find 'your correct' eye placement... I wouldn't worry either too much about trying to take the whole field of view in anyway with one go... I prefer just to find a comfortable position, relax and allow the view to dissolve away at the edges (rather than to a hard edge).

Best of luck!

It is a great eyepice - I won't be giving mine up, even with the 21mm Ethos!

Damian

[MartinB]

Paulo, I've never tried a 31mm Nagler but I do have a 17mm type 4. This has an adjustable eye piece cup that can be pushed in or out with a series of clicks. The positioning is vital. Too far out and you start to loose the FOV, too close and kidney beaning. The trick is to move the cup as far out as possible without the FOV becoming restricted. You place you eye up against the cup and things are ok.

Does the 31mm have a similar arrangement?

[pvaz]

Pvaz - I asked my observing buddy to clarify, and we both came to the same conclusion that we straight align our right eye to the eyepiece lens... with the rubber eye guard just brushing the side of the nose, so I suppose our eye would be just inside the eye guard.

I personally find then that I can rotate my eye in it's socket around the entire field without any blackouts.... With the Ethos, I do rotate my head as well slightly as I find it too painful to strain my eye to the field of view... and again, no real blackouts either....

I'd give it a few more goes first to see if you can find 'your correct' eye placement... I wouldn't worry either too much about trying to take the whole field of view in anyway with one go... I prefer just to find a comfortable position, relax and allow the view to dissolve away at the edges (rather than to a hard edge).

Best of luck!

It is a great eyepice - I won't be giving mine up, even with the 21mm Ethos!

Damian

Your description is the best position I found to take the FOV without experiencing blackouts. I was seeing blackout when I tilted the head left and had my face touching all the circle of the rubber guard, with the eye closer to the lens, in order to avoid any stray light. It's seams to be just bad eye placement, I'll certainly use it a lot more before making a decision.

On the Ethos I have no problems at all, the image is great anyway I look at it. Great eyepiece! I only wish I could have a few more of them but for now I have to be content with just the one as my wife ain't enjoying this astronomy thing as much as me. I guess I can't complain much as I started in September with just some binos and I spent money on it every month since then. I had to promise her a trip to Phi Phi islands in Thailand in order to get this last EP upgrade!

[pvaz]

Paulo, I've never tried a 31mm Nagler but I do have a 17mm type 4. This has an adjustable eye piece cup that can be pushed in or out with a series of clicks. The positioning is vital. Too far out and you start to loose the FOV, too close and kidney beaning. The trick is to move the cup as far out as possible without the FOV becoming restricted. You place you eye up against the cup and things are ok.

Does the 31mm have a similar arrangement?

Unfortunately the eye piece cup on the 31mm T5 is fixed. I have to get used to the position till it becomes natural.

[pvaz]

Ok, I'm more relieved now!

Been outside for about 45 min juggling around the clouds and I'm much more pleased with the Nagler. I only sow 1 blackout when using it alone and 2 with the barlow. I managed to keep my eye well placed and after just 10-15min it was starting to come naturally. I'm confident I can get used to it with a bit more practice.

[oceanheadted]

Paulo,

I'm glad to hear you're getting on a bit better with the Nagler. I only have a 7mm T1, but just love looking at the moon through it. The extra field of view (which is sharp across the whole field of view) invites your eye to wander across the image. I'm waiting for my 4mm UWAN to be delivered from FLO so it will be interesting comparing the eyepieces.

How do you find the extra weight on your telescope, the 31mm is a bit of beast I think?

Cheers

Alan

[pvaz]

The telescope is behaving well with the extra weight. I did have to tighten the tension knobs a couple of turns. Now it's a bit stiff in Alt but it's either that or risk a nose dive.

[John]

The telescope is behaving well with the extra weight. I did have to tighten the tension knobs a couple of turns. Now it's a bit stiff in Alt but it's either that or risk a nose dive.

It is a little awkward Paulo - I used to use my 31mm T5 with my Skywatcher 8" dob and had to do the same. Just wait until you see the Veil nebula though the 31mm with the OIII filter - it will all be worthwhile - that sight alone was the main driving force behind me going for a "Terminagler" and it is worth the admission fee IMHO.

[pvaz]

After using the EP a few nights under good and bad conditions this are the "new" conclusions:

- Regarding focus/sharpness: It shows great images with pinpoint stars across the field. The very edge of the FOV is more sensitive to the focus. It's like I can have a little play with the focuser and the stars in the center are sharp. The ones near the edge need an exact position of the focuser where the entire FOV seams to be in perfect focus. The views of open cluster in particular gain a lot from this FOV quality.

- When barlowed: Using it with the BigBarlow 2x you can notice a slight drop in quality. On good seeing nights it's barely noticeable. I tested it on 2 nights where there was a low altitude thin mist that caused the image to brighten a lot and this effect was much more noticeable with the ep+barlow. Of course the most likely cause was the extra magnification making the atmosphere problems more noticeable but still the drop in quality was there.

- Regarding the blackouts: I managed to correct my eye position and it's becoming comfortable to use so I rarely get any blackouts now, still I don't have this problem with any of my other EPs. When used with the barlow the eye position is much more critical and I found myself reaching for my 15mm budget EP a few times to have a more comfortable view despite the soft edges and smaller FOV. I would say the Nagler 31 doesn't "barlow" very well at least compared to the Ethos that gives me the same quality and comfort whether it's barlowed or not.

[John]

I reckon the Nagler 31 is one that would work better with a Powermate because that won't affect the eye relief or the edges of the FoV. I agree that the Ethos is more "barlow friendly" though. Either way it's a lot of weight on the focusser !.

[michael.h.f.wilkinson]

Interesting comments. If I win a lottery, I might exchange my Paragon with the Nagler 31;)

The Powermate design is quite different from Barlows. I never used to like barlows, but my Meade TeleXtender is more similar to the Powermate, and has excellent performance even with ultra-wide-angle EPs.

[John]

....but my Meade TeleXtender is more similar to the Powermate, and has excellent performance even with ultra-wide-angle EPs.

I'm trying the 2" 2x Meade TeleXtender at the moment and, from the limited time I've used it, I'd agree it is very Powermate-like in it's performance.

[michael.h.f.wilkinson]

I'm trying the 2" 2x Meade TeleXtender at the moment and, from the limited time I've used it, I'd agree it is very Powermate-like in it's performance.

It had better be, for that price:p

[pvaz]

I reckon the Nagler 31 is one that would work better with a Powermate because that won't affect the eye relief or the edges of the FoV. I agree that the Ethos is more "barlow friendly" though. Either way it's a lot of weight on the focusser !.

True the focuser does get a lot of weight but it seams to handle it well.

The only item that gives me some trouble with the focuser is my Antares 2" to 1.25" adapter which centers EPs and haves the 2" filter thread. This adapter is so large I kind of have to force it in the focuser and sometimes the focuser "gives in" and travels inward when I'm putting the adapter in. To preserve the focuser I'm using the original adapter that came with the scope every time except when I need to use a filter on my 1.25" EPs.

Unfortunately I can't use the Ethos as a 2" EP as the focuser doesn't have enough out travel to reach focus. I need to use it with one of the adapters to reach focus.