Temperature focus compensation FLI Atlas

My FLI Atlas is a lovely focuser however it does not have temperature compensation.  After many frustrating nights ducking out to fix my focus after one or two images I decided to do something about it.  Enter Maxim DL Scripting.

I figured I could read the temperature of the focuser store it in a file on disk and then at the end of the next image read the temperature again and compare it to the one I wrote to disk.  If the difference was substantial (i.e. some number in my case 0.2C) I could move the focuser an specific amount.  In my case for the LX 200 it measured up to be about 0.19mm per 1  C.

Maxim dl scripting is pretty straight forward except when it comes to the Focuser.  If you create the object directly you can end up with two instances of the focuser object so what I did was use the Generic Hub and pointed Maxim to this and the Hub I pointed to the FLI Focuser.  The code is setup accordingly.

I run it at the end of each image (configure under Autosave->Script).

Code attached as a vbs so it only works under windows.  Download it from here it’s only a few lines.


Finally a picture. M16 in Ha.

13x 15 min subs 2 days after full moon.

Taken using a set of Don Goldmans 3nm Ha filter, using an FLI Proline at -35 C on a 12″ LX 200.