Takahashi LE 24mm

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Subject: Re: vote by xxx.xxx.42.11
By: Anonymous (xxx.xxx.208.147)
In Reply to: Anonymous (xxx.xxx.42.11) (Original Vote)
Date: 05/06/2008 05:39:41 pm PDT
>I've been thinking about writing a review of this ep for a little while and finally decided to put something in print. As I unpacked the eyepiece, the first thing I noticed was how light the coatings were. I've owned a couple of other LE's and they all had nice dark coatings. Well, the real test is under the stars so when the clouds cleared I popped in the ocular and panned over to the sword of Orion. In my 80mm, F6 achro refractor I immediately noticed something was wrong. Only the stars in the center of the field of view were sharp. All around the edges the stars grew long comet-like tails. This was about halfway out from the center. I tried a number of my other eyepieces and the problem went away. It wasn't the sky, it wasn't the scope, it was the eyepiece. I decided to fiddle with it some more so put it back in the diagonal and tried other targets as well as making more careful note of what I was seeing. What I found interesting was the central portion of the field of view was perhaps as sharp as anything I've seen. I was picking up faint pinpricks of stars not seen in any other eyepiece. Also in the "bad" area the comet tails didn't get worse from the 50% range to the 95% range. They were either there or not, but didn't continually get worse as you approached the edge like a Meade Superwide I used to own. Curious.
>I decided something was wrong with the eyepiece and have returned it.
>You'll note I did not put a number rating and that is because I've owned a number of Takahashi products in the past and they've all been first rate. I consider this one an anomaly and don't want to skew the results of others.

You are experiencing the infamous curvature of Pentax eyepieces above 10mm. In other words, if you have, say, the 20 mm in sharp focus in the center, anything outside of that (and I'm not talking about extreme edges) will appear to be out of focus. This is a problem with Pentax eyepieces above 10, but not so at 10 or below. You did not get a lemon. I have used the 10 and it's superb, but I hated the other long focal lengths because of this problem.

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