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500mm / 90mm Maksutov-Cassegrain f/5.6
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PostPosted: Fri Sep 17, 2021 12:51 pm    Post subject: 500mm / 90mm Maksutov-Cassegrain f/5.6 Reply with quote

Hello,

because im dipping my toes int astro photography im interested in all telescope type of lenses.

I found this one for a good price.

the outside is pretty dinged up but the glass is pristine. Sadly the focus mechanism is a bit of, sometimes it reacts sometimes it does nothing... and sometimes i reacts with delay ;P turned the nob it has a 2sec latency.

Anyone has any experience repairing this kind of lens ?

Thank you
Karel


PostPosted: Fri Sep 17, 2021 3:07 pm    Post subject: Reply with quote

Can you post a picture of the lens?


PostPosted: Fri Sep 17, 2021 3:50 pm    Post subject: Reply with quote

jamaeolus wrote:
Can you post a picture of the lens?


Ofcourse ^^ here you go Wink




PostPosted: Fri Sep 17, 2021 11:37 pm    Post subject: Reply with quote

This is just a guess, but the little hole in the side of the focus knob should have a grub screw. A small screw that "locks" the knob onto the focus shaft. If that is loose it might give the symptoms you describe. it is probably an allen type but is possibly flathead orperhaps philips. See if you can tighten that screw.


PostPosted: Sat Sep 18, 2021 12:20 pm    Post subject: Reply with quote

jamaeolus wrote:
This is just a guess, but the little hole in the side of the focus knob should have a grub screw. A small screw that "locks" the knob onto the focus shaft. If that is loose it might give the symptoms you describe. it is probably an allen type but is possibly flathead orperhaps philips. See if you can tighten that screw.


Apart from this + any other defects, you might need to adjust your expectations- telescopes with this style of focusing knob focus very slowly, by design. Allows accuracy, but slow.