Education from University Optics please...

Started by fct-150, 12/24/2013 11:25AM
Posted 12/24/2013 11:25AM Opening Post
Many of you know I am a very rabid ocular hoarder. So I finally landed a rare one, and he's in stellar condition; a UO "flat top" 16mm Konig. Haven't yet had time to test it in the Takahashis (I know the Brandon and Juno will reject it) and so while I wait for good skies, I have a few questions for the UO experts...

1) What is the age difference between the flat top 16 with the model numbers and the ones without? Mine has the additional numbers as seen in the photos.

2) How far back do these go? I have the later (early '90s) 16mm Konig, which is volcano-top style.

3) Is the leather pouch original to the eyepiece? I have, in the past, come across eyepieces (and camera parts) that were accompanied by leather pouches. The eyepiece is a perfect fit inside it, but the pouch has no label.

Thanks for the education boost... I'll need it in order to get my diploma at UO!!

Attached Image:

fct-150's attachment for post 58066

Just a few thoughts:

8) FS-152SV sitting in the office
grin Japanes super lucky zen observatory garden
:S Meade ETX-90 finder scope position
shocked Hino Optical Mizar 120SL observatory model
:C SR-4mm eyepiece with a 3x barlow in a 60mm refractor
8O Zeiss Victory 7x42 SFs
wink Having over 135 vintage oculars to play with
smile My life surrounded by wonderful friends and impeccable optics
Posted 12/24/2013 11:27AM #1
Here's a photo of the pouch.

Attached Image:

fct-150's attachment for post 147966

Just a few thoughts:

8) FS-152SV sitting in the office
grin Japanes super lucky zen observatory garden
:S Meade ETX-90 finder scope position
shocked Hino Optical Mizar 120SL observatory model
:C SR-4mm eyepiece with a 3x barlow in a 60mm refractor
8O Zeiss Victory 7x42 SFs
wink Having over 135 vintage oculars to play with
smile My life surrounded by wonderful friends and impeccable optics
Posted 12/24/2013 11:55AM #2
Andy, My best guess is an 80's vintage Koenig and I do not remember a leather bag supplied with them either. Paul
Posted 12/24/2013 03:32PM #3
Andy, I have a UO 16mm Konig that I purchased in the early '80s, but it does not have the model #. IIRC, UO used to send their oculars out in small, "red velvet" lined boxes. I know they did in the early '70s.

I've gotten rid of a number of oculars over the years, but(for some reason) I've held onto this Konig. It was actually my favorite 'deep sky' ocular when I had an 8" F7 Newtonian. smile

Darian R.
Posted 12/26/2013 08:53AM | Edited 12/26/2013 09:22PM #4
Hi Andy, that U-number is an individual Serial number ala camera lenses, so it is the original Konig. And it's from UO's Professional Series of Ortho eyepieces which at 1st were only single-coated. Like camera lenses of the period, they also came in individual leather cases. The UO Pros were identical to the GOC Saturn-logo eyepieces sold by Telescopics; the Telescopics' 16.3mm was called the Galoc. And the UO Pros have Japan MOP (or just MOP on the 28mm Ortho) stamped underneath the edge of their top caps, like Meades' Research Grade line (all of the RG Wide Fields were of 1-2-1 Konig construction & not true Erfles). With top caps removed, there is no discernable difference from the UO Pros or the Telescopics eyepieces; they are identical. Later UO offered an NS-stickered flat-top Konig line in several focal lengths followed by volcano-top Circle-Tee Konigs or Konig II's, but in long-focus scopes these are inferior to the original serial-numbered version in sharpness & FOV. I either still have or have had several complete sets of all of these. When I'm back home after the Holidays I can check S&T ads for dates if you want.
Posted 12/27/2013 05:40PM #5
The Konig is a variation of a 4 element ocular, one of many that is possible with 4 pieces of glass. Other similar performing oculars are the Orthoscopic, Plossl, Symmetrical. They all have almost totally similar performance in terms of Sidel aberrations (spherical, coma, astigmatism, field curvature, distortion), as well as color correction.

Each of them can have variations where one aberration such as off-axis astigmatism is traded for less field curvature. With 4 elements the designer has such a number of freedoms as to make almost an infinite number of different designs and give them all a different name. Those names are simply pure marketing attempts, and none of these miriad 4 element oculars has any real advantage over any other.

An example is the Plossl or Symmetrical ocular, which is easiest to make, but has the least marketing wow factor these days and has fallen out of favor. Yet it is totally undestiguishable (is that a word?) from an Orthoscopic when designed for similar performance.

Any one of these variations can be orthoscopic - the term means without distortion. This type of ocular was originally developed for microscopy where a scale was fitted at the focal plane and used to measure across a portion of the magnified images. Being without distortion meant that the scale was accurate in the center as well as the edge of the field. It does not mean that the image was free of astigmatism at the edges, so a star image is not necessarily perfectly round at that point.

Nowadays almost all oculars have compensating optics placed before the focal plane which flatten the field, remove the astigmatism of the main optics, and sometimes also increase the magnification by various amounts so as to achieve very short focal lengths using longer focal length main optics (built-in barlow magnification for short). The downside is an increase in the number of elements, along with more internal reflections and some loss of contrast - typically only seen when viewing planets.

Rolando