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Threekor (3 Beach) 220

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#1 CharlieB

CharlieB

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Posted 28 June 2020 - 10:14 PM

This scope made a brief appearance some time ago on CN and I was lucky enough to be offered it by its previous owner.  Most of you know I am rather taken with small scopes, so I couldn't let this one get by me.  I've finally gotten around to plying with this little scope and was pleasantly surprised.

 

It's a 40mm f/5.5 scope that reminds one of a miniature Tasco 9VR.  

 

IMG_0519 - Edited.jpg

 

It has all the accessories of a 9VR.  This is a very handy ring that also perfectly fits many 50mm scopes.  It has a 1/4-20 trdpod thread and a camera post.

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It has a lightweight version of the Vixen slo-mo attachment that holds the scope pretty well.

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The finder is a peep sight with a pair of sharpened grub screws at right angle that attaches to the scope ring.  Center the desired object at the two points and you have your target in the eyepiece - in theory, of course

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It came with a barlow and an extension tube, which is needed with the barlow.

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It has no R&P focuser, just a pull tube with a lock, but that works pretty well at low to medium powers.

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Here's the fully assembled scope on a standard photo tripod.

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And it takes a Vixen 1.25" visual back!  This setup gives a whopping 5.5x view.

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I wasnt expecting great optics from a 40/220 scope, but again, I was quite surprised.  The objective is somewhat overcorrected, but still give very good images - sharp out to about 90% of the FOV with a very small amount of CA.  Here's the Ronchigram.  

 

Threecor outside - Edited.jpg

 

 

 


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#2 CharlieB

CharlieB

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Posted 28 June 2020 - 10:19 PM

A highly cropped shot of my TV dish.  This is a prime focus shot with a Nikon D3300.  Almost no CA.

 

DSC_1997 - Edited.jpg

 

And just for comparison, here's a 9VR, SV50 and the Threekor.  The Threekor compares quite favorably with the SV50.

 

IMG_0534 - Edited.jpg


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#3 CharlieB

CharlieB

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Posted 28 June 2020 - 10:22 PM

I did flock the entire scope and that did wonders for the contrast.


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