Putting FOV aside, how good is Nagler?

MooEy · Post by **MooEy** » Fri Feb 16, 2007 10:42 pm

like most people say, skip those nagler for planets. a gd ortho prolly beats it in terms of contrast and stuff. however deep sky wise, the wide angle offering from televue and pentax are pretty hard to beat.

if u already have a slow scope, skip those shorter focal lengths since u wun get much fun out of them. the mid focal lengths are pretty nice on a slightly faster scope, say f6 or so.

one of the reason y people are willing to pay premium for the pentax and televue stuff pretty much have to do with the edge performance. on faster scopes, say f/6 or faster, the edge performance of the premium stuff are pretty gd. as gd or better than a plossl.

the pentax generally are nicer in the shorter focal lengths due to the gd eye relief. infact i was quite surprised to see the diff between a xl 14 and my pano 15.

however do note the prices. although most people feel that the xl7 has more contrast and eye relief than the t1 7mm, the big diff in price still make the t1 7mm a gd choice.

~MooEy~

ariefm71 · Post by **ariefm71** » Sat Feb 17, 2007 12:06 am

... and hence the XWs are my all-time favourite series of eyepieces for deepsky and non-tracking planetary use.
_________________
Richard Low

I heard you just ordered two pieces from our dear friend :-)

Canopus Lim · Post by **Canopus Lim** » Sat Feb 17, 2007 9:15 am

The T6 Naglers are good. The standard orthos does not beat it in contrast or resolution on-axis in any way; whatever faintest lowest contrast details I can detect it as easily with the Nagler; sharpness wise, they are just as sharp. Also, I feel it may even have a slight edge compared to the standard ortho. The difference I find is the colour tone with the Nagler slightly warmer which I prefer for Jupiter though. The T1s are very old..it is almost as old as me

.. 80s technology compared to the T6 which are year 2000 technology. Coating technology has improved by leaps and bounds so I won't be surprised that newer complex eyepieces can match up with the cheaper/ older orthos in terms of performance. The Nagler T6 has greater than 90 percent transmission over the visible wavelengths, the T1s are probably in 80 percent transmission range. I doubt that the latest multi element complex eyepieces can match up with the latest orthos (with modern coatings, Pentax orthos/ HD orthos/ Baader othos) on-axis though but the difference is small.

For 80 degree AFOV, I feel that the Naglers are the way..for 70 degrees AFOV the Pentax XW. If you want very specialized planetary, get the latest orthos with the best coatings as only those can beat the Nagler T6. Also, comfortability wise, it is subjective. I do not find the T6 uncomfortable to use and when compared to the orthos, it is more comfortable. The eye relief is long enough that I don't grease the eyepiece with my eye lashes.

Also when talking about the Pentax XW and Naglers.. hey they are well designed eyepieces. There is 'no better one'. It depends on what you want. I like huge AFOVs so, the Naglers are my choice. For long eye relief and good performance the Pentax XW. Size wise, the T6 are smaller and compact in size and will not cause any balance problems for alt-azi mounts.

elton · Post by **elton** » Sat Feb 17, 2007 10:14 am

Naglers are not a single design and can vary quite a bit from type to type. Type 6s are pretty good in optical quality, probably somewhat similar to radians and XWs sharp across the field, but they have a bit of distortion which is apparent on planets (elongated jupiter). ER is ok but not great. The 16T5 I tried was also not bad but like rest of T5s is a bit tight on ER for such long focal lengths with the exception of the terminagler. The T4s have better ER but my experience with the 22T4 is that it is a step behind in image sharpness and contrast compared to XW. I still keep the 22T4 because it is one of the shortest FL eyepiece in 2" (apart from 20T5), may be useful in fast scopes. For planets on premium scopes, specialised planetary eps can squeeze that little extra to give an extraordinary view. At 10-20mm, ER of orthos begin to be quite usable. For planets, get a TMB supermono / pentax ortho / XP / AP SPL for less $$$ than a nagler

elton · Post by **elton** » Sat Feb 17, 2007 10:26 am

Forgot to add that to get the "spacewalk" feeling, you will need a T4 or a big T5 (terminagler) for the combination of ER and FOV.

rlow · Post by **rlow** » Sat Feb 17, 2007 2:18 pm

however do note the prices. although most people feel that the xl7 has more contrast and eye relief than the t1 7mm, the big diff in price still make the t1 7mm a gd choice.

For me, the nagler 7mm type 1 may be ok for deepsky but not even comparable to a 7mm ortho, so the type 1 cannot match the 7XL or 7XW. The nagler 7mm type 6 is probably better, and I would like to do a test someday, so if anyone with a type 6 wants to test, let me know. The Pentax XWs are generally much cheaper than the Nagler Type 6 series.

For planets, get a TMB supermono / pentax ortho / XP / AP SPL for less $$$ than a nagler

For critical planetary observation, these are the ultimate planetary EPs, together with the Zeiss ortho. The only one I have yet to test is the pentax ortho.

rlow · Post by **rlow** » Sat Feb 17, 2007 2:35 pm

I heard you just ordered two pieces from our dear friend

Yes, you are right, Arief. News travels very fast around here!

Canopus Lim · Post by **Canopus Lim** » Sun Feb 18, 2007 1:55 am

Yup the T4s have really the spacewalk feeling and there is where all the money goes into the T4s for.

anat · Post by **anat** » Sun Feb 18, 2007 9:47 am

Thank you for the valuable comments. I want an eyepiece in the middle range. Unfortunately, the 14XW and 20XW are well known for field curvature. I tested a 15 mm TV plossl two days ago and found that its eye relief (10mm) was a bit tight. My long eyelash left oil on the lens after 1 min and that caused blurry views. So, I get no benefit of the better optics in the Plossl if the lens is always dirty

I think I need to wear glasses at an exit pupil of 1 mm+ and the FOV reduces tremendously. My amount of astigmatism is 3.0 diopters for my left eye and 5.0 diopters for my right eye !!

I am considering Nag 13T6 and 12T4. From your experience, which one is better in terms of image quality and comfort. If you have any better choice, please feel free to tell me. And if the field curvature in the 14 XW is minimal at F/9, I would also like to try.

Thank you.
Anat

Canopus Lim · Post by **Canopus Lim** » Sun Feb 18, 2007 5:20 pm

I think the 14 Pentax XW or 12mm T4 Nagler is to be chosen because of your astig. You need to wear your glasses at those focal lengths.

A rule of thumb for not wearing glasses is that for 1 diopter of astigmatism, the maximum exit pupil is 2mm. Yours is more than 3 diopters so I think it would require about 1mm exit pupil or less to be 'glass free'. The 13T6 would be at the borderline or may not meet the requirement of glass free due to astigmatism for your case.