Oculare Ronchi

Codice articolo: Ronchi

By means of easily to interprete stripe patterns, you can see how good your telescope is

High quality grating in 1.25" nose piece
On a plano-parallel glass substrate, 10 lines per mm are etched in. This leads to a high testing precision.
Easily interpretable - if the stripes are straight and parallel, everything is okay (see picture on the left)
By interpreting deviations, the optical errors can be determined
Also ideal to find the focal plane

By interpreting the stripe pattern, you can classify optical abberations and the overall quality.

In combination with the star test, you can make much more useful statements about an optical system an an interferometric test can do.

Advantages and characteristics of the Ronchi eyepice:
Precise aluminium body with 1.25" diameter - no tilting
Fine optically polished glass substrate with precise grating for high test precision
The grating side of the glass is exactly on the same level as the hard stop of the 1.25" barrel. So the focal plane of the telescope can be measured exactly.
10 lines per millimetre allow a test precision close to a optical bench

How do I use the Ronchi eyepiece?
Operating is easy. Just put it into the focuser as any other 1.25" eyepiece. Aim at a star of medium magnitude and center it. A comfortable star especially for Dobsonians and other telescopes without tracking motor is the pole star as it does not move and has the correct brightness.

Turn the focus wheel until 3-5 stripes are visible. Then, examine the stripe pattern.
Lines straight and parallel: Everything is OK
Curved lines: Hint to spherical abberation
V-shaped pattern: Decollimation or Astigmatism
Lines with "hills" or "valleys": Hint for a zone error

Illustrated manual
There is a manual with sample images, you can download the PDF here.