Magnification is a division, not a number on a box · review
A 25 mm Plössl with a 50-degree apparent field, coated optics, a metal body, rubber eyecups and a filter thread.
The bottom line The workhorse focal length, honestly described — including the place where its own range gives less.
Twenty-five millimetres is the eyepiece that finds things. On a 900 mm telescope it gives 36x with a wide true field; on a 1500 mm Maksutov it gives 60x and is still the easiest view to work with. It is the eyepiece that ought to be good, and it is the one most often supplied cheaply.
Fifty degrees, published. And a note that the 40 mm in the same range gives only 42 degrees, because a 1.25 in barrel cannot pass a larger field stop. That second sentence is the kind of honest constraint that rarely appears in an advertisement.
“Coated” — one layer, at least one surface. That is the weakest of the four labels. On a four-element Plössl with two air-glass pairs it is not fatal, and it is a step below the fully multi-coated claims elsewhere on this shelf.
Comfortable, which is the other reason this focal length is the one that stays in the focuser. A Plössl’s eye relief scales with its focal length, and twenty-five millimetres is where spectacles stop being a problem.
German, French, Italian and Spanish Amazon stores ran from 34 € to 37 € on the day of the survey.
British Amazon store lists it in local currency, which the euro range above sets aside.
American Amazon catalogue holds a record for it that nobody is selling.
Figures as Keepa reported them on the day this page was last updated. Stock and pricing shift without warning.
Prices quoted in this text were read on 17 September 2026. The live price is at the top of the page.
| Focal length | 25 mm |
|---|---|
| Apparent field | 50 degrees, as the maker publishes it (42 degrees for the 40 mm of the same range) |
| Eye relief | Rubber, against side light |
| Barrel size | 1.25 in with a filter thread |
| Optical design | Plössl, four elements |
| Coatings | Coated lenses, as the maker words it |
| Weight | Not published by the maker. |
| Supplied accessories | Not published by the maker. |
| Amazon reference | B00ODR0G5A (same reference on 6 Amazon marketplaces) |
| EAN | 4049467438632 |
Because it gives the widest true field on most telescopes, which is what finding things depends on. It is also where eye relief is comfortable and the exit pupil is generous.
Omegon states that the 40 mm of the same range has a 42-degree field rather than 50. That is a consequence of the 1.25 in barrel limiting the field stop, and publishing it is more candid than most.
8 mm focal length · apparent field stated two ways · four elements
A four-element fully multi-coated Plössl of 8 mm focal length in a metal 1.25 in barrel, with a fold-down rubber eyecup and a filter thread.
Best for: A step up from a supplied short eyepiece, on a case-based collection
≈ $17
10 mm focal length · four elements in two groups · 65 g
A 10 mm Plössl with four elements in two groups, fully multi-coated, in a metal housing with a filter thread, published at 65 g.
Best for: A dependable mid-power eyepiece for a case that is being built properly
≈ €25
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
