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Eyepiece Focuser Insertion

Beginner Equipment Eyepieces
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#1 Dave1UK

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Posted 26 September 2022 - 04:57 AM

Hi,

 

Only recently just got myself a Newtonian reflector telescope and wondering on the proper equipment usage/whether there are advantages to using it one way to another.

 

In regards to fitting eyepiece on the focuser.

 

focuser.png

 

Should the eyepiece be inserted fully until coming to a stop? Or should it be inserted only as far as it can be secured by the screws?

 

Wondering whether there are any benefits to either, also as when inserting fully depending on the eyepiece and length, when engaging the focuser fully (collapsed mode) the eyepiece pops out internally close to the secondary mirror.

 

Thanks.



#2 quercuslobata

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Posted 26 September 2022 - 05:02 AM

Welcome!

 

I would fully seat the eyepiece all the way down as it will be more stable. I think the only reason not to do so would be if for a particular eyepiece that you needed to back out further to get to focus, but even then I wouldn’t have it sticking out too much, and would probably observe on grass just in case.


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#3 wrvond

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Posted 26 September 2022 - 05:06 AM

For normal operation the most secure position for the eyepiece in the focuser is fully inserted. If you somehow have a focuser that is able to contact the secondary mirror when it is fully racked in, there is something wrong. Most focusers do not extend into the OTA more than an inch or so and generally not into the light path at all.


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#4 Starman47

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Posted 26 September 2022 - 06:09 AM

Welcome!

 

I would fully seat the eyepiece all the way down as it will be more stable. I think the only reason not to do so would be if for a particular eyepiece that you needed to back out further to get to focus, but even then I wouldn’t have it sticking out too much, and would probably observe on grass just in case.

Ditto



#5 Ernest_SPB

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Posted 26 September 2022 - 06:41 AM

Right EP position is "inserted fully until coming to a stop"

In this case EP has less chance to get off-axial shift/tilt.


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#6 Dave1UK

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Posted 27 September 2022 - 03:39 AM

Thanks all appreciated.


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