Wednesday, June 22, 2011

13mm Nagler Type 6: First Light

In his book The Urban Astronomer's Guide: A Walking Tour of the Cosmos for City Sky Watchers (Patrick Moore's Practical Astronomy Series), Rod Mollise says that wide field eyepieces will help in deep sky observing by providing enough field of view while keeping magnification high. It is well known that high magnification darkens background so contrast between object and the light polluted background improves thus the observer can see the object easier.
As a stargazer observing under heavy light pollution, I followed his advice and decided to get a 82-degree eyepiece. I made an extensive research on optical performance and availability of the alternatives and decided to get 13mm Nagler Type 6. 13mm Nagler gives 94x magnification (a very useful magnification) on my 8 inch dobsonian with apparent field of view of 52 arcminutes. I bought it from amazon.com at about 220$.
The eyepiece is larger than my 26mm Meade Series 4000 Super Plossl but smaller than 32mm Celestron Plossl. Physical quality was very good and the dust caps fit securely. The first look was very pleasant though not stunning (i expected more immerse effect)  and the large field of view was really obvious. I compared the view with 26mm Plossl and 2x Barlow and of course Nagler's image quality was better. But this comparison showed me a shortcoming of Nagler compared to Plossl: Lack of eyecups. I find it more difficult to use Nagler after placing my eyes on the eyecups of the Plossl. The Nagler is still pleasant to use though and when i switched back to Plossl from Nagler, i felt as if i was looking through a narrow pipe. I have not looked to a planet or the Moon with my new eyepiece and i am looking forward to observe them and report Nagler's performance. I am glad that i got this eyepiece and hope to enjoy it for many years.

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