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1/4" tripod version of a Vixen rail

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#1 toucansam



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Posted 21 March 2019 - 06:02 AM



I have an Orion 90mm Mak with a simple 1/4" tripod thread on the bottom.  I have a Vixen-compatible mount to which I am trying to attach the scope.  I picked up a SkyWatcher Star Adventurer Ball Head Adapter, and unfortunately the threaded post is 3/8" (as is, it turns out, the bottom of the Vixen-based mount).  


First question: is 3/8" a standard in the astronomy world, or is it a standard with the Vixen and Vixen-compatible mounts?


Second question: is there an easy way to attach a Vixen rail to a scope with a 1/4" thread?  I have looked at a few rails from various vendors and can't seem to find something that I can say will work with 100% confidence.


Sorry for the newbie questions.



#2 Messierthanwhat


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Posted 21 March 2019 - 02:43 PM

First, 3/8" is a photographic standard. Most quality photo tripod heads, including ball heads, have 3/8" mounting threads. That's why that size thread was used on Skywatcher's adapter for a ball head.


You can actually use just about any Vixen-type dovetail bar, but you probably prefer a short one, and you have to check the saddle of your mount to be certain of compatibility, and of how you need to make the connection. Of those I know, the most likely to be compatible would be the ADM VDUP4, or the shorter, 3" version. It has a shouldered slot on the bottom that allows for attachment with a 1/4" socket-head bolt of appropriate length that will fit flush with the bottom. You supply the bolt, which is a fairly common item at a good hardware store.


Orion sells this adapter precisely for that purpose, also. It costs less, but as you can see from the photo, it has a bolt head and tightener that protrude from the bottom. It's compatible with the mounts for which it's designed, because those mounts have a large recess right in the middle of the dovetail saddle, where the saddle attaches to the mount. If your mount has that recess, then that adapter should work for you as designed. 

#3 macdonjh



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Posted 22 March 2019 - 08:38 AM

I ended up buying rings and a short Vixen dove tail bar for my Orion 100mm Maksutov.  I just couldn't keep the scope from twisting and turning on my mount with that single center screw holding it.

#4 luxo II

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Posted 23 March 2019 - 04:51 AM

OP there are 3/8" to ΒΌ" adapters, camera stores sell them typically for a few dollars.

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