TeleVue Nagler Type 4 22mm


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Subject: Moved Message
By: Anonymous (xxx.xxx.240.34)
Date: 05/14/2002 01:11:58 pm PST
Just an update from an earlier post. I had been using the 22mm NT4 with the pupil guide. I thought it would block any ambient light and improve contrast. Then I happen to use a friends and found it much more user friendly. I quickly realized it was the pupil guide. So, at least for me, I much prefer the eyepiece without the pupil guide.

Also, at f7.9 stars a pinpoint to about 95% of the field, very impressive. At f4.5., as noted earlier, it does suffer a bit.

Overall a good eyepiece, but perhaps a little over hyped.


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Subject: Re: vote by xxx.xxx.58.120
By: Anonymous (xxx.xxx.131.87)
In Reply to: Anonymous (xxx.xxx.58.120) (Original Vote)
Date: 08/22/2002 12:24:04 pm PST
Since f4.5 Newtonians have considerable coma away from the optical axis, why are you surprised to see it with a wide field eyepiece like the 22mm Nagler?


>Tried my new 22mm Nagler last night and could certainly see why people have not be overly impressed. In my f4.5 10" Newt there was a significant amount of coma, even stars in the center of the field did not compress well.
>
>Also had the 20mm Nagler T2 on hand and was anxious to cpmare them given remarks in some circles that the 20mm T2 was better (a classic in fact). In comparing the two eyepieces I did not see a significant improvement viewing through either. The 20mm T2 was sharper on axis, stars compressed better, but its off-axis performance was worse (apparently one of the much talked about trade-offs in eyepiece design). Contrast bewteen the two was very close with a slight edge for the 22mm T4. The object viewed was the Orion Nebula. I used it because it offered nebulosity and stars at the same time.
>
>I agree with a previous review, asking someone to buy a paracorr for an eyepiece that is suppose be design to be sharp in fast scopes (and charging a hefty price for it) is not a real good endorsement of your own handy work.
>
>I own many Televue eyepieces and love them, so this is not Televue bashing, but they really missed the mark with eyepiece. I will be keeping it until I can find another eyepiece in this focal length, with as wide a field.


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Subject: Re: vote by xxx.xxx.214.54
By: Anonymous (xxx.xxx.131.87)
Date: 08/22/2002 12:27:54 pm PST
Corrected for f4 does not mean it corrects the optical defects inherent in the telescope. It just means that the eyepiece can accept an f4 (relatively fast) light cone without the image falling apart completely!


>Regarding the 22mm Nagler T4, this eyepiece is something of a disappointment, at least when used in my faster scopes. Having first purchased a 12mm T4, I expected the same qualities from this one. Instead, stars were quite comatic around the outer 1/3 of the FOV. Being quite expensive, I found this unacceptable for an eyepiece line claimed to be corrected down to f/4. This one is not.
>
>However, all is well when used with a Paracorr which corrects the view to almost perfect. Also, the 22mm works well with the 4x Powermate. If you have a fast scope (not sure at what f/ratio the problems begin to arise) and want to use the 22mm T4, you need a coma corrector. At more than $730 for the 22mm and a Paracorr with the tuneable top, this is an expensive combination. Still, the views ARE excellent once you have what you need. The 17mm does not seem to have these problems to the same extent, but I use it with the Paracorr anyway, now that I have one.
>
>Conclusions: Too expensive, not well-corrected at faster f/ratios, requires a Paracorr, Powermates well, stunning widefield views once everything is in place. I'd give it a "6" or "7" if it weren't for the final views attainable. A reluctant "8".


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Subject: Re: vote by xxx.xxx.58.120
By: Anonymous (xxx.xxx.20.73)
In Reply to: Anonymous (xxx.xxx.131.87) (Original Message)
Date: 03/05/2003 03:20:30 am PST
Well, the obvious answer is because the Nagler's are suppose to help minimize aberrations like coma and astimatism. It doesn't seem to do a very good job in this case and in a relatively short focal length. The longer focal length 31mm Nagler type 5 does a better job.

Next easy question.


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Subject: Re: vote by xxx.xxx.6.69
By: Anonymous (xxx.xxx.4.1)
Date: 05/06/2008 05:16:38 am PST
If you see coma, it's almost certainly down to the telescope. I'm not saying that you have a bad primaray, but the coma on an F/4 Newton is HUGE. No eyepiece will correct for that; they have not been designed to do that. A paracorr has.

Good luck,

Marc


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