Essato 2"

This was my first Primaluce Lab purchase and since then I have expanded my collection. The quality of their products is amazing and the customer service is equally good.

With Schmidt Cassegrain Telescopes (SCT) like the EdgeHD 11 your focus can be affected by something called mirror flop, where the primary mirror, which is also used for focus moves slightly as the scope tracks the target across the sky. That is so common that Celestron even puts mirror locks on the back of the scope to minimize this. But that requires going out to the scope to unlock/lock the mirror each time you focus. The thing is temperature and changing filters also cause the need refocus so that doesn't really support automation very well.

The Essato inline focuser addresses this issue by allowing mirror lock but puts the fine focusing in the image train. It also has the benefit of solving for that missing */- mms of back focus as the entire imagery train is moved. The focuser is beefy and can carry up to 8kg of additional payload which is more than enough for a complex imagery train.

I connect the focuser directly to the backplane of the scope (or reducer if in use) as it has the most capacity and other components like the OAG/Filter Wheel/Canera need to have a fixed distance.

I'm currently not using this model as I needed just a little bit more back focus spacing to add in an Off-Axis guider so I purchased the Essator Low Profile (LP) which doesn't have as much adjustment range but gives me back 30 mm of back focus.