Eyepieces - "Ring of Fire"?

[Macavity]

Eyepieces - "Ring of Fire"? No reference to Johnny Cash or Curry (FNAR)

But, in the context of eyepieces, I was wondering if anyone was familiar with this term or phenomena? Independantly, I observe that some (even quality) eyepieces have this "orange glow" that either sits at the very edge of view or sometimes propogates over the whole FOV as one moves around. A bit like "technicolour blackout" or (my understanding of) kidney beaning. Maybe that is it? :shock:

Has anyone else see this? Does anyone know it's cause? Frankly *darkness* seems to cover a multitude of these "sins", that manifest terrestrially... Perhaps one shouldn't care! Some "culprits" are my 21mm Hyperion and a (now sold) Televue 8-14mm Zoom. Some eyepiece manufacturers do seems to be able to avoid this particular manifestation though...

One of many things I have long wished to better understand.

[Brass n glass]

I got that orange with a 21mm Hyperion as well. But it was just the eyepiece cooling down. After 10 to 15 minutes the orange always disappears. I think it's because of the large number of wide lenses in there. I also get a bit of orange glow for about 5 minutes on a 2" Poyser 37mm Plossl with 6 elements. I've never had it with a 1.25" eyepiece.

[Macavity]

Thanks for that (not just me etc.). Odd that it is a thing that rarely gets mentioned in the Hyperion 21mm context. (Compared to the slightly reduced AFOV blah-blah). For me, the other "classic case" is the Antares W70 19mm, which has a very bright peripheral orange ring. "Obviously" some sort of edge-thing, but not quite the same as e.g. non-blackened lens edges, which gives rise to a (colour-free) "brightness" around the edge of field. But, whether through temperature, dark adaptation of pupils (another favourite?) etc., a LOT of these problems do seem to be *mercifully* reduced under DARK skies...

[Brass n glass]

I think a lot of strange things can happen in fast telescopes where the objectives/primaries are working under such steep curvature that unexpected distortions can appear. I have 4mm and 12mm Vixen lanthamum eyepieces which both work very well in my Mak and an old f13 achro refractor. In my modern f6.8 apo the 4mm is fine but the 12mm produces bright orange fringes round the moon and planets and along linear objects like telegraph wires in daylight.