I own the following superlative full-frame Nikon SLR lenses,
105mm f1.4 (3")
135mm f1.8 (3")
200mm f2 (4")
300mm f2.8 (4.1")
400mm f2.8 (5.6")
600mm f5.6 (4.1")
800mm f5.6 (5.6")
all of which will outperform expensive telescope objectives at distances of a few hundred metres, and equal them at infinity.
In their mounts, they all produce circular images with diameters exceeding 50mm before vignetting is noticeable.
I wish these to also serve as telescopes, for occasional terrestrial and frequent general astronomical use. I live in S.E. England about 50 miles from central London, so night skies aren't that dark..
I have devised a method to accurately add (orthogonally) a detachable 1.25" telescope eyepiece to the camera-end of these lenses.
There are two ready-to-use existing gadgets which already do this, available second-hand. One is expensive, Nikon-branded and of medium optical quality. The other is cheap and of poor optical quality.
I want better.
What 1.25" eyepieces do you suggest I buy for my own one? I understand angle-of-view considerations for eyepieces, but don't have an idea how important this will be for this application.
Kellner? Plossl? Or else?
Focal lengths (3 will do)
3.6mm or 4mm, 9mm, 23mm were my original idea.
SVBony? (I've read all the threads on this BB relating to SVBony - opinions differ)
Celestron? The latter two look like they came out of the same Far East factory as SVBony ones...
From https://svbony.aliex...m/store/2801114 you can see (Products > Kind of Eyepiece) that SVBony has many ranges: Kellner, Plossl and 7 different angles from 58 to 80 degrees, with the 62 degree ones the only ones labelled Aspherical, but are also the cheapest...
Here's a summary of the SVBonys - the last number is the average price for an objective from that range:
80 deg 11/16 mm $84 for 2 $42
58 deg 2.5/4/6 mm $103 for 3 $34
72 deg 9/18 mm $64 for 2 $32
60 deg 9/12/16/20 mm $93 for 4 $23
68 deg 6/9/15/20 mm $89 for 4 $22
66 deg 6/9/15/20 mm $86 for 4 $21
PLOSSL 4/6.5/10/12.5/15/20/25/30/40 mm $103 for 9 $11
KELLNER 9/17.5/25 mm $29 for 3 $10
62 deg ASP 4/10/23 mm $25 for 3 $8
Then, we have unknown origin ones, like
which extermally look a bit like the 62 deg Aspherical SVBonys but are at only £10 for 3!
The Meade Series 4000 Plossl's are here (UK prices)
and here's an S/H Meade 9.7 mm on ebay, at only a little less when you factor in postage:
while for 5-6 times less money you can pick up this attractive looking one:
So, please - WHAT SHOULD I PLUMP FOR, given I will be using them with premium Nikon long primes?
Edited by Nikon-Shooter, 09 October 2019 - 08:20 PM.