Red Dot Finder Camera Mount

 



Project

The other day while fighting to get my Canon/Hutech 500D pointed at the Heart and Soul nebulae with a Nikkor 180ED attached to it I thought of how nice it would be if the camera had a finder scope. With the camera in an awkward position on the mount and no bright stars easily visible in the viewfinder getting my target framed was not easy.

A camera being used for wide-field imaging doesn't need a very accurate finder system so a simple and lightweight unit was what I had decided would be the best. Stellarvue refractors ship with a nice little red-dot finder (RDF) and I have two of them. These are just the standard, inexpensive plastic units that seem to ship with every small refractor on the market but they work very well. On to the mounting.

A scrap piece of plastic was put into service and master machinist and vintner Dave Rubenhagen milled it to fit in the Canon's hot-shoe and then cut a 75 degree dove-tail on top for the finder. The drawing at the bottom of the page shows the dimensions used. When making things that go into hot-shoes always use plastic as you don't want to short any of the terminals in the shoe.

The completed mounting holds the finder quite solidly and in a position where, if I needed to, I could still get my eye to the viewfinder.

Description

The fitting itself is very small and very light. Here is a picture of it leaning on a standard 16-pin dual-inline-package integrated circuit chip. Mine isn't made to the dimensions shown in the drawing below being about 1/4" shorter than I'd really like but the block of plastic on-hand dictated the length used.

The bottom of the dovetail is about 3/8" if you follow the diagram and use a 75 degree cutter to form the dovetail. This will fit many telescope finders along with many air-gun or small-bore rifle sights out there on the market.

The plastic I used is probably nylon or perhaps Delrin; I'm not sure. It's fairly strong but won't take a huge amount of stress. It is strong enough though for normal usage in astro-photography or even sport photography.


Shown to the left are the dimensions (tailor to suit especially if your RDF isn't a Stellarvue).

The critical dimension for the hot-shoe is the distance between the bottom of the fitting and the bottom of the slot, not really the width of the slot. Don't worry if your slot cutter is bigger than the .035 used on mine.



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