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Prism Shoot-Out


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19 minutes ago, Bino-viewer said:

Hi

Why the need for the Helical focuser ?

Doesn't it eat up more lightpath mm's ??

I should imagine it adds a few mm. The Baader T-2 is sold with a helical (and even a nosepiece!) so I added an extension. I need the helical for fine focus on scopes with only a single speed focuser. So basically, all my Mak's and my 150mm Newtonian. The Baader helical, more or less permanently threaded into the Newtonian's GSO focuser, can cause in-focus problems with some eyepieces. 

 

Basically I suppose it is a trade-off in light path or in-focus for fine focusing.

 

seXykMBl.jpg

 

The GSO Newtonian always had focusing problems anyway lol.

 

 

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O3IDsOal.jpg

 

I was a bit concerned by stacked filters possibly touching the prism surface. Threading the Double Polariser into the diagonal nose bought it into direct contact with the visual back baffle on my Mak's.

 

P3rZ8gYl.jpg

 

So the solution was to use a GSO Barlow barrel as an extension tube.

 

G1jpE5Ll.jpg

 

Admittedly it looks a bit Heath Robinson, but I haven't had any in-focus problems.

Edited by Nightspore
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  • 7 months later...

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