Ok, I appreciate the 0.965" long-running thread but I'd like a bit more info on ep types as well as specific replies to a couple of questions...most of my knowledge (what little there is! ) comes from "Olden Times" when I actually looked through scopes - my OCD by-product of CCS (Classic-Collector Syndrome) now has me trying to understand these a bit better as well as the other questions here!
I understand that Huygens, Huygens-Mittenzwey & Ramsden ep's are all non-cemented types...correct..?
I always thought "SR" signified "Simple Ramsden" (plano-convex, convexes-facing) - but does it mean a "Symmetric Ramsden as in aspheric symmetrical..?
I know a little about Erfles...but what about the "AH" - is this an "Achromatic Huygens" or an "Airy Huygens"..? (a little knowledge really is dangerous!)
I'd like to use my old-time Herschel Prism - I understand an ND filter is a good pre-requisite but what value ND should be used to give best advantage to the HP's qualities...I think it was Dave from NZ or perhaps JonH gave me some forgotten advice a year or so back...
I know about the "Terrestrial Erecting" & standard 90° diagonal devices btw.
Lastly the Carton device - I haven't checked the thread sizes but an initial (& possibly stupid!) thought is that it is an ep projection fitting for a camera: the knurled element allows turning from "K" to "H" (Kellner to Huygens?) & the top view shows where an ep can click-fit into said device - any answers..?!?
I have a few others including the Tasco/Towa "Zoom" barlow (6mm-18mm) (last pikky) which did seem to function ok using one of the ep's the other night: I was always told to view any of these old barlow-type units with extreme circumspection...unsure atm whether it is a compound lens element or one of those old "single" nasties...once I find my 0.965" to 1.25" adaptor I guess it'll be unlikely that I'll continue to use any of these ep's but learning a bit about them is always good!