My new Nagler 16mm T5 (vs Pentax XL14)

[A McEwan]

Hi all.

I recently acquired a 2nd hand Nagler 16mm T5. I have owned Pentax XL14 for years, along with several other Pentaxes (5.2mm XL, 10.5mm XL, 30mm XW) but always found the 14mm to be somewhat less perfect than the other eyepieces. I found the curved field noticeable, especially when switching down from my Vixen LVW 22mm which has a perfectly flat field in my scopes. It was a minor niggle, but it was there nonetheless. So I wondered if a mid power Nagler would be a better option...

I got a chance to compare the two eyepieces the other night, using my ED80. I viewed the Orion Nebula, Pleiades, M35 and Double Cluster. Remember, I consider Pentax optics to be the best I've ever used - hence why I've kept them so long!

The view of the Orion Nebula with the Pentax was pretty stunning. Nice 3D effect to the nebulosity and the stars were nice and sharp. Only fault was the stars at the edge of the field were out of focus slightly. Switching to the Nagler threw up some interesting results. The stars across the whole field were in focus, barring some evidence of the astigmatism in my eye. I had noticed this effect in the Pentax too and since I'm due an eye test again soon, I must make a note to get a specific value for the amount my eyes have. The effect on the stars near the edge due to astigmatism was no worse in the Nagler though. Anyway, the detail in the inner part of the nebula was ever so slightly sharper in the Nagler! A tiny difference, but I was looking for tiny differences! Ever so slightly increased contrast in some of the boundaries between brighter and darker areas of the nebulosity. I know that the slight difference in magnification (42x Pentax, 37x Nagler) may have affected it, but I would have thought it would work the other way around?

Very nice view but the eye relief was noticably shorter in the Nagler and I was aware of the closeness of my eye (and lashes) to the lens. However, folding the rubber eye cup down made it easier to see the whole field of view with ease, and resulted in more viewing comfort. There were no blackout issues with the Nagler - at all! The Pentax does have some minor eye positioning foibles (for me anyway), and the 14mm has always been the least easy for me to use.

Moving on, M35 was virtually the same in both eyepieces, and the smaller (or more distant) NGC cluster nearby was evident through both. The Double Cluster showed some small difference in favour of the Nagler. I compared views of the very faintest stars detectable through each eyepiece, and found that some 'borderline detectable' ones were seen slightly easier through the Nagler!

The Pleiades was a hands-down winner for the Nagler too. As well as giving a wider field to frame the object better, the nebulosity seemed slightly more noticeable too.

Thing is, I am really surprised about this! I never expected the Nagler to show things better than a Pentax XL. Ok, wider field yes, but what's contained within the wider field also seems to be slightly more contrasty and sharp. I am really surprised! The only downside is the short eye relief, which is noticably less comfortable than through my Pentaxes.

However, my Pentax 10.5, 5.2 and 30 are all superb eyepieces and will definately be staying with me, but the comparison between the XL14 and Nagler 17mmT5 has shown that in real terms the Pentax (for me at least) does not live up to the performance of the other Pentaxes or the new Nagler!

Hope this helps someone to buy expensive new eyepieces...

Ant 8)

[barkis]

You have supplied a fairly in depth account Ant. I feel it is going to be a big help to anyone hovering over a decision to spend the big bucks.

These reports are a big help in that respect.

Ron.

[John]

Thanks for that report Ant

I love my 16mm T5 Nagler with the tight eyerelief being the only (slight) drawback with it - but at least the eyecup is nice and soft so you can nestle you eye into it. It is a very sharp eyepiece.

The T6's have only 2mm more eye relief but it is noticable - just as well though as they have much less flexible eye cups !.

I do think that the multi-coatings on the current range of Naglers is suberb which I'm sure is why they compete so well with simpler designs.

I would like to try some Pentax's though - I've never looked through one as yet

John

[johninderby]

My 16mm T5 is one of my favourite eyepieces. While the Penatax eyepieces may have a more neutral colouration I like the Nagler's sharpness and wider field.

I've found that the Baader Moon & Skyglow filter works particularly with Naglers as it gets rid of the slight warm tone on lunar / planetary. On the moon it gives a very natural grey colour and is the only moon filter I use now.

John