lunette TEC 140 2019-01-14T10:52:27+00:00

TEC140 F7 et sa caméra CCD Proline FLI 16803

 How to improve the shift of Focuser Starlight Instrument FT3545

shift on focuser


You can see on this image the focuser FT3545 from starlight Instrument.

With an important load of more 10 lbs and a very long lenght between the focuser and camera, the problem of shift on the focuser begin to be a problem for long exposures; I can keep a good alignement with 10 minutes but after that I have some flexures due to the shift of my focuser.

You can see near the camera the result of shifting ! easely 2 mm of shift, when you feel the focuser on your hand the shift come from it.

Werner, manager of Starlight Instrument give me the good manier to improve the lift of the focuser without lateral shift.

« Hello Nicolas,
It would be my recommendation to have the hidden one a little tighter than the outside one. You want to adjust it so that you can still slide the draw tube up and down without too much force. Once preloaded it should be fine. Do you have a little oil on the tracks. This really helps and you do not need much. We use a q-tip with about one drop of regular motor oil on it and wipe it on the areas that come in contact with where the Teflon guides are (you can’t see these, they are in the inside of the focuser housing). You don’t need much and you can put a little on the front and the back. It will make a huge difference. Let me know if you try this and see if there is a difference.


When you try to see where is the shift, it is between two tubes of my focuser, a very small shift is feeling here on the top draw.

The lenght of my train setup exagerate this problem and my camera is moving ! ff


You need to loosen this screw for a good lift of focuser.


The first thing is to verify your Robofocus or external motor.

Verify also the screw of motor, this one need to be tighten for a good mouvement and you need to find the good force, mine is tighten but not too much.


Put your focuser at the end of focus for a complete view of it.

Find a good oil and try to put it on the surface of second tube of focuser, try to lift it some times up and down for a complete penetration of the oil inside the tube.


To finalise this operation try to tighten the inside screw and keep in mind that your focuser continue to lift up and down !

After this operation the shift disapear definitivly.

You said heavy load on my TEC140 ? and shifting problem ? Nooooooooooooo !!!

last setup, more than 10 lbs load !