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Old 28-04-2021, 05:40 PM
Mark.Tanner (Mark)
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Problems viewing with 6.3 focal reducer on 8" Nexstar

I have an 8" nexstar and have recently bought the Celestron 6.3 focal reducer. I'm finding it very hard to focus. So far I've only focused objects within 20m, and can't focus on distant trees (let alone planets etc!). I have moved the focuser all the way anti-clockwise to no avail. I'm worried about taking it too far clockwise as I'm worried the mirror will fall off or something (is that a thing?).

When I add the focal reducer I need the light to be focused further back. Is that achieved by clockwise or anti-clockwise rotations?


It's also worth mentioning that I'm using this with a binoviewer, which requires an even further back light focal point.

Last edited by Mark.Tanner; 28-04-2021 at 06:08 PM.
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Old 28-04-2021, 06:50 PM
Zuts
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Quote:
Originally Posted by Mark.Tanner View Post
I have an 8" nexstar and have recently bought the Celestron 6.3 focal reducer. I'm finding it very hard to focus. So far I've only focused objects within 20m, and can't focus on distant trees (let alone planets etc!). I have moved the focuser all the way anti-clockwise to no avail. I'm worried about taking it too far clockwise as I'm worried the mirror will fall off or something (is that a thing?).

When I add the focal reducer I need the light to be focused further back. Is that achieved by clockwise or anti-clockwise rotations?


It's also worth mentioning that I'm using this with a binoviewer, which requires an even further back light focal point.
You may need an extension for the binoviewer, assuming that by back you dont mean inward. Try it first without and it should easily come to focus.
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Old 28-04-2021, 06:54 PM
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Camelopardalis (Dunk)
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Check the length of your light path.

The Celestron reducer only has 105mm backfocus.
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Old 28-04-2021, 06:57 PM
Dave882 (David)
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Hi Mark- SCTs have got heaps of focus travel but do have limits. I havenít used the 0.63x with binoviewers but use regularly with my 8Ē celestron cpc800 with absolutely no focus issues. Iíve only had problem reaching focus with a 36mm eyepiece and 2inch diagonal AND a 1.25mm adaptor. And then only just - but I know the binos use a lot of space. Maybe donít worry about the reducer when binoviewing as itís mainly used for imaging anyway.

Best to test it under the night sky. Donít worry about turning the focus knob all the way it wonít drop off. Just donít keep forcing it when it gets tight.
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