Focuser tilt makes me go crazy - Forums

Topic starter

27 days ago

I recently bought a 533mc pro and was really excited to test it with my 72apo tecnosky refractor thinking it would get rid of the tilt i had from my old nikon m48 adapter but i found out some of the tilt was because of the telescope focus assembly itself. I went out last night to troubleshoot the tilt and i found out it stays in the same place even if i rotate the telescope, this convinced me that it was the focuser and not something from the imaging train. The OTA has 4 screws close to the focuser, 2 big gold ones that adjust the tension and 2 small black ones that are slightly off to the sides that i think adjust the tension on the bearings. I also tried to play around with the screws last night but i couldnt find the sweet spot at all, tightening the golden tension screws only got me to a point but the stars were still elongated even if i went back and forth with the tension. I also tried adjusting the black screws but they dont seem to do anything, they move in very easily. I will attach a photo of the screws am talking about and hopefully somebody with a similar focus assembly can help😅

Edit: I removed the fine focus assembly which was supposed to be on the other side of these screws for easier adjustment and checking for play/wobble.

Edit: I forgot to mention that the stars did in fact improve after i played with the tension but they still were elongated.

📷 IMG_4841.jpeg

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alpheratz06

16 days ago

I’m not an apo72 expert, but my understanding is that the screws you mention only after bearing pre-load and tension, the effect on tilt being marginal.

Did you check for lateral backlash ? Tension ajustement may help reduce backlash and possibly part on the tilt.

If there no or very little backlash, the tilt result from initial alignment defect and/or shock damage.

A way around approach could be to use a tilt plate ( I don’t know if 533 has a buit-in one) to compensate tilting.

You can assess tilt amplitude from the analysis of an image with ASTAP for instance.

Razvan Rautu

Topic starter

15 days ago

📷 IMG_4853.jpegalpheratz06 · Jun 9, 2026 at 09:39 AM
I’m not an apo72 expert, but my understanding is that the screws you mention only after bearing pre-load and tension, the effect on tilt being marginal.
Did you check for lateral backlash ? Tension ajustement may help reduce backlash and possibly part on the tilt.
If there no or very little backlash, the tilt result from initial alignment defect and/or shock damage.
A way around approach could be to use a tilt plate ( I don’t know if 533 has a buit-in one) to compensate tilting.
You can assess tilt amplitude from the analysis of an image with ASTAP for instance.

Hi, you were right about the lateral backlash thing, theres quite a bit and adjusting the tension screws helps a lot to remove it but theres another problem, the long golden plate that is on the focus tube isnt perfectly aligned to the hole it slides through when i tighten the tension screws, which means that the hole tube is not straight lateraly😔 Also you might be the first person that helped me idientify the backlash😅📷 IMG_4854.jpeg

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