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Is a two-stage focuser needed for an f/5 scope?

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#1 derangedhermit



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Posted 24 November 2012 - 08:22 AM

Assume old eyeballs, if that makes a difference.

I have a JMI that I can upgrade to a two-stage focuser (at considerable cost). I'm wondering if it is worthwhile.

Visual use only, on a Dobsonian.

#2 kfrederick



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Posted 24 November 2012 - 08:39 AM

A bigger knob helps .

#3 Ed D

Ed D


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Posted 24 November 2012 - 09:05 AM

Not if observing at lower magnifications. However, if you want to get really fine focus at high magnification, such as when observing planets, then it really is nice to have, especially for older eyes. I also use big focus knobs on my f/8 Dob and it does help. Small knobs are a PITA no matter what the scope speed or type of focuser.

Ed D

#4 operascope


    Mariner 2

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Posted 24 November 2012 - 12:16 PM

A cheaper option might be to use a helical fine focuser. However, I like 2 stage for all my scopes. Even makes my f/9.4 better.

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