Basically, all the significant aberrations of an optical system can be seen in a Star test, but for reliability you need very steady air, and above all a lot of experience.

By contrast, the Ronchi test works well in unsteady air, and even beginners are able to interpret the images.

What you get:
The Gerd Neumann Ronchi Eyepiece consists of a 1.25″ eyepiece barrel, made of black anodized aluminium, in which a small glass plate is mounted with a vapour-deposited grid. Some Ronchi eyepieces use a grid pattern on a piece of film or even laser printed. These Ronchi eyepieces usually deliver a streaky image with low contrast, and make the interpretation of the images very difficult, especially for beginners.

By contrast, this Ronchi eyepiece uses an optically polished glass plate on which a grid is deposited with 10L/mm.

The glass plate is mounted so that the grating surface is exactly in the same plane as the outer stop. This allows you to very precisely determine the position of the focal plane.

The Ronchi eyepiece is supplied in a plastic container with a Quick Start Guide in English and German.

The post Gerd Neumann Ronchi Eyepiece 10L/mm appeared first on Modern Astronomy.