Nikon NAV 目鏡測試報告

[社長]

最近Nikon天文目鏡引起一定關注，以下貼出一篇APM Markus Ludes發出的測試報告。有興趣的朋友我可以代訂。

當然這些目鏡與行星月面專科目鏡的取向及定位是有些不同的：
viewtopic.php?f=5&t=167

測試報告
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I was out to test the new NIKON NAV and have had 1 old NIKON ( 60x/75x) 72° in such test.

Sky conditions: bad seeing, rolling in and out clouds , about 4 mag star only

the scopes I used

- 24"F/4.3 Starmaster Dobsonian , one time with Tele Vue Paracorr and 1 time without
- Takahashi TSA Apo 120 mm F/7

1, the below mentioned fieldstops are not field stops diameter but entrance lens diameter at the 1.25" barrel . I believe in the 17.5 mm and 14 mm this diameter is equal to the field stop. But the 5 mm have a smaller fieldstop ( but bigger entrance glas ) then the 7 mm. The fieldstop is on both internal, so I cannot measure it

2, the quality of field correction ranging similar as on the older NIKON widefields. Best was there 7 mm , followed by 10 mm folled by 14 mm followed by 17 mm

- The NAV 17.5 mm has the lessest good edge correction. In the 24" I can use about 75 % of the FOV very good without Paracor and with Paracorr it shows only little distortion. In the TSA the 17.5 mm show a clear edge distortion ( asigmatism ). It have a superb ghostlight/straylight controle, no visible reflection when Mars or Sirius moving through the field and light blocks immediatly when the bright object moves behind the edge baffle

- The NAV 14 mm works similar then the 17.5 mm but with a bit better field correction

- The NAV7 mm works as perfect comacorrected as the old 7 mm ( 60x/75x) sharp to the edge even without Paracorr. In the TSA 120 they are both are very similar, however the old 7 mm show Mars till the very edge racersharp and perfect round and when Mars moves behind the fieldstop, the FOV is black. The new NAV 7 mm is only about 98 % as sharp to the edge, and when Mars moves behind the fieldstop, I see a little light beam entering the edge field . In the 24" scope however the new NAV 7 mm show a hint better edge correction and no ghostimng at all, while the old 7 mm seems to introduce a very little reflection towards the cente rof the field, when a Sirius moves behind the fieldstop

- the NAV 5 mm is perfect in both diffrent scopes with and without pracorr , no complain, very sharp to the edge.No ghosting.

The NAV5 mm is the top of the Line from that 4 diffrent focallengthes, followed by the NAV 7 mm, the NAV 14 mm, then NAV 17.5 mm. All of them are extremly comfortable to use. The design is a kind of flat field design, you notice it, if you looks from barrel side into the eyepiece to any kind of straight line. Moving the line to the edge of the Field the line keeps straight, while other ultra wides show a more or lesses bending line