Tuesday, December 19, 2017

My DYI Piggy-Back Camera Mount for NexStar 4SE

One reason why I bought myself a Celestron NexStar 4SE was so that I could use it for astrophotography, especially to have the scope mount guide a DSLR camera for wide-field to short telephoto astro-imaging.

I had purchased a Vixen-style bar mount for my DSLR cameras (Canon) to put in place of the OTA (the telescope itself), like this one:
But it did have the disadvantage of not being able to easily set up the GOTO since the scope would be off the mount. Then I would have to hope that the mount and tripod did not move in the process of demounting/mounting the scope a very real problem that would throw off the GOTO alignment.

I checked online to see if there was a ready-made piggy-back camera mount for the NexStar 4SE but they were a bit expensive for such a simple device... one costs from $40 to $90, like these:
   

So checking around in my "bits and pieces" box (filled with old telescope parts that I have hung on to just for situations like this) I found a telescope "split-ring" mount but it was too big in diameter for the 4SE.  Having purchased a drill and tapping bit, I simply created the necessary four holes & threads in the ring at 90 degree intervals to accept adjusting bolts with a button nut on the end of it (to protect the barrel of the scope).
    

The split-ring already had a place where I could put in a threaded camera bold and a piece of rubber (glued) that would hold the DSLR camera in place.
  

Attaching it to the scope was simply a matter of unscrewing the split ring and removing the ring from the barrel.
 


One advantage of this setup also is that it places the camera nearer to the center of gravity on the scope. Also the scope's mounting bar can be slide forward or backward to aid in balancing the overall setup.

 

Another advantage is that I can rotate the split-ring to keep the camera from blocking the red-dot finder scope.
Mounting in this way also allows one to view through the eyepiece at the back of the scope in the normal way or add a webcam to the back port of the scope.

Though it works just fine I plan do some post-modifications:
* Remove the screws and add thick rubber padding inside the rings so that the threaded screws are not necessary
* Cut the split-ring tightening screw down so that the (brown) washers are not necessary.
* And paint the rings Celestron orange or black to match the scope.

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