The Tri-Batinov Mask

Many of you will be aware of the Batinov mask which is an excellent aid for focusing a telescope but may not be aware of a newer version called a Tri-Batinov mask.   This produces a more complex pattern as seen below.

In this image the telescope was perfectly collimated and onecan see that the three central ‘lines’ are symmetrical within their boundinglines.  Should the secondary mirror beout of collimation, one or more of these will be offset and, by adjusting theappropriate secondary adjusting secondary screws, can be brought into thecentre – making it quite easy to collimate the secondary.

Its use to helpcollimate an 8 inch Ritchey-Chrétien

I wondered if one would assist in the collimation of my 8-inch Ritchey-Chrétien telescope.

A wide variety of Tri-Batinov Masks are sold by Rother Valley Optics.   However, they do not have one for the 8-inch Ritchey-Chrétien and I was  intrigued to see how one might use one to confirm its collimation state and perhaps help make some final adjustments.  The ‘Lazy Geek’ has made a YouTube video: