Well, I’ve designed solid mounts so that I can mount my red dot finder to my camera and to the barn door tracker. What was going wrong in the first version is that there was a lot of wobble in the mounts. My fault, because my design for the shoe for the finder was inherently wobbly. The current attempt is based on a design on thingiverse.com, for basically a type of dovetail rail that the finder scope can attach too. The finder comes with it attached to an adapter to a Synta style shoe. And there’s absolutely no problem with that, except in my setup.. Here is a link if you want to buy one:
As you can see, the finder itself is clamped on to a pedestal that then attaches in to a shoe on a telescope… In my case that pedestal is so high, it limits the positions I can angle my camera to. So on thingiverse.com is a rail meant for my particular tracker that would accept a similar type of finder scope. Not exactly mine, but I used it as a starting point for my design. I ended up with a rail I can bolt to my tracker, has a low profile, and then I can slide the finder on and off and there is no wobble.
I also melded that rail design to a hot shoe mount, printed that, and that fits nice and snug into my camera hot shoe also without wobble.
So the idea, as I think I explained in another blog entry, is that since the finder has alt/az thumbscrews on it that are normally used to align it to a telescope, I couldn’t count on those screws never turning. So without a reference of what 0 alt/0 az is, I saw no way to align it to my barn door tracker. There’s nothing on the tracker with which to sight the north star, to correct the aim of the finder. So my theory goes.. if my hot shoe is square and level to my camera lens axis, I can put the finder onto the camera, align it to the camera while sighting a star in the exact center of the camera frame and then adjust the thumb screws on the finder to line it up– conveniently my camera displays the square central focus spot through the viewfinder so I can really get exact. Once the finder is lined up, I can move it to the barn door tracker, and do a polar alignment.
So that’s step 1 in eliminating star trails. The tracker has to be well aligned to the pole. And I have to wait, looking like a week, for clear skies to try it.
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