Eyepieces
Six elements at 60 degrees, or a Plössl at 50?
These two are not interchangeable: 12 mm and 25 mm give different magnifications in the same telescope, and the choice of one over the other starts there. What the comparison is really about is what the extra elements buy — a wider apparent field, and a twist-up eyecup instead of a fixed rubber one.
| Compared on | X-Cel LX 12 mm (93424) | Plössl 25 mm |
|---|---|---|
| Focal length | 12 mm | 25 mm |
| Apparent field | 60 degrees, as the maker publishes it | 50 degrees, as the maker publishes it |
| Eye relief | Twist-up rubber eyecup | Rubber, against side light |
| Barrel size | 1.25 in, threaded for filters | 1.25 in with a filter thread |
| Optical design | Six elements, fully multi-coated | Plössl, four elements |
| Coatings | Not published by the maker. | Coated lenses, as the maker words it |
| Weight | Not published by the maker. | Not published by the maker. |
A tick means one listing published something the other did not, or published a better figure. It does not mean the product is better, and the column is not a score out of anything: a maker who says less loses lines here without losing a comparison. The two verdicts below are where the page is settled.
The wider view. Sixty degrees against fifty is a visibly larger window at the eyepiece, and a twist-up eyecup is the mechanism that makes an eyepiece usable with and without spectacles. Six elements is also more glass for light to cross, and the listing does not say how the surfaces beyond the first are treated.
The one whose design is a known quantity. A Plössl is four elements in two pairs, it has been made for decades, and its behaviour at the edge of the field is predictable. At 25 mm it is the low-power eyepiece most observers reach for first, and its coating is at least described.
It shows a wider window at the same magnification. True field is apparent field divided by magnification, so at equal focal length the 60-degree eyepiece frames more sky than the 50-degree one.
Because the focal length is a choice about magnification, not about quality. What is being compared here is the design — how many elements, how wide a field, what eyecup — which applies at any focal length.
Not by itself. More elements allow a wider corrected field, and each added surface is one more place to lose light and add reflections. It is the coating on those surfaces that decides which effect wins, and one of these two does not publish it.
12 mm focal length · 60° apparent field · six elements
A six-element fully multi-coated eyepiece of 12 mm focal length with a 60-degree apparent field, a twist-up eyecup and a knurled rubber grip.
Best for: The eyepiece that stays on the planets, used with gloves on a cold night
≈ $93 / £88 / €106
25 mm focal length · 50° apparent field · four elements
A 25 mm Plössl with a 50-degree apparent field, coated optics, a metal body, rubber eyecups and a filter thread.
Best for: The finding eyepiece — the one that stays in the focuser most of the evening
≈ £32 / €34
Any figure written into the body of this page was true on the day it was written. The amount shown next to each instrument is requested from the retailer as the page loads, and it is that amount, not the text, that stands.
