|
Basically, they pretty much mean an optic design. Think: Nagler = Rolls Royce, Panoptic/Pentax = BMW, Plossl = Ford/Holden, Kellner = Hyundai etc. if you get what I mean. Of course, you can get pretty impressive Hyundai's and entry level BMWs...but you can still expect the BMW to outperform the Hyundai in certain ways!
A Plossl has been around for ages and used to be regarded as "the bees knees" in optics (1970-80's). There are also Kelners, Orthoscopic etc that have been around for even longer. Generally, these designs give you a view of 50 degrees or less.
Panoptic is a term for TeleVue eyepieces that offer around 70 degrees. My Pentaxs also give 70 degrees, but the layout of the lenses inside the eyepiece will be different, possibly even a different number of elements (number of actual lenses), in different groups, this is basically lenses that are "stuck together" in the assembly. Some groups may have just one element, sort of defeats the definition of the word a bit.
Orion Stratus give 68 degrees and also have another layout of lenses.
Naglers give 82 degrees and have yet another layout of lenses. Generally, the wider the field of view, the higher the price. Compare a Nagler to a Plossl of the same focal length and you will see what I mean.
From my observations, the actual lens that you place your eye against varies in size with the design of the optic. My Plossls have a big piece of glass in the 32mm which is easy to find in the dark while a 4mm has a tiny pinhole of glass you have to find in the dark. A lot of the wide angle designs (Pentax, Stratus, Hyperion, Panoptic, Nagler etc) generally have a big bit of glass regardless of focal length. The eye glass of my 7mm and 30 mm Pentax XWs are the same size and easy to find at night!
If you look at the optical layout of some of the eyepieces on the manufacturer websites, you will see what I mean.
Collimation? I think most here would say you can't go past a decent Cheshire, but then again, this may also open yet another can of terminology worms.
Just learn a few buzz words and a bit about some of them, and you will seem like an expert (to the general public at least)....I do!
|