Eyepiece Types


In the following table we have listed some of the most common eyepiece types with their pros and cons. The graphics at the left side are to be understood as an example of the eyepiece type, there are a lot of modifications on the market. As an example, the Kellner design is also available as a reversed Kellner, which means, that the two-lens element is at the bottom side. Furthermore one can manufacture any design in a careless way, that you do not have to think about inherent pros and cons - but for that we do our testing.

Additionally something about the viewing distance (the eye relief): as a rule of thumb eyepieces have an eye relief of about 2/3 of their focal length. This is uncomfortable, if the focal length is less than 6 to 10mm, as you have nearly to touch the eyepiece with your eye. Therefore modern Long Eye Relief eyepieces combine e.g. a Barlow lens with a Ploessl design, which leads to an eye relief of about 15 or 20mm for all focal length. However, adding more lenses will have the effect of more stray light, loss of contrast and generally image degradation - at least if not very careful manufactured. Such eyepieces should not be used with an additional Barlow lens.










Simple, two-lens type





Apparent field of view is small (ca. 30-35°), not achromatic





Also cheap


not achromatic, small field of view (about 45°), eyepieces with long focal length not recommended for optics of F/5 or F/4





4-lens design


Nice image quality, achromatic

Often used for planetary observations


Small field of view (about 35-40°)




Standard in modern astronomie


Relatively cheap to have, very good image quality


Field of view just about 45°, below 10mm focal length small eye relief



Super Ploessl


modified Ploessl, 4- or 5 lenses. Often just Ploessl with an added “Super“


Field of view about 52°, if really a modified Ploessl. Contrast and image quality very good


A little bit more expensive than Ploessl, eye relief like Ploessl




Standard design for wide angle eyepieces


Nice apparent field of view (about 65°), not to expensive



Near to the edges not good with fast optics (F/5, F/4)


Nagler and Super- or Ultra- Weitwinkel


Very big apparent field of view (up to 85°). Very good image quality possible, but depends strongly on the manufacturer. Can be build up for use in F/4 and F/5 - but expensive in that case.



Nagler: Very expensive and remarkable distortion


Very expensive.


If cheap: Do not use with fast telescopes.





Thanks to Skyproject here: I “loaned“ the graphics from there. I would have asked them for a permission, but there was not contact address given…