I have a little time to devote to my second hobby, DIY some useful accessory for astronomy. To complete the excellent
Pentax75 SDHF put down a drawing of the various elements of a precision screw focuser (such as those that are on photographic objectives) to focus on where you turn right and left a ring is the optical forward or backward toward the focal position.
The system is also quite simple to design, and I'm sure I'll make good use.
I have all the materials you need, good quality pieces of aluminum that come from industrial recovery, the usual tornietto model for me is to help primary.
few hours of work, a good pile of chips, and that's coming out the new gadget. I particularly cared
games operation, leaving a minimum of 0.05 mm between the screw-nut pairs, and 0.02 axial play.
I tried to lubricate the coupling with grease, but I've finally replaced with a few drops of engine oil, to make it fluid motion.
The size of the focuser are relatively small as the seat of the Pentax has a diameter of 60mm (standard-) while the side-room home has a diameter of 50.8mm (2 ") which is the standard of the fittings of various photography astrophotography accessories.
Obviously I have this accessory built to stock, but can also be used for visual focus when focus more precisely where in fact there is a gear ratio 1 / 10.
In practice, it is divided into three parts, an element that inserted in the Pentax, a nut coupled to the first body, a screw coupled to the nut, and structured by three pins (see photo) in the first body that allow you to slide forward / backward + / - 1 mm around the block but the spin.
clear that we must first bring the sleeve to the approximate location of the lens focus, block and then carefully put in focus. For
outfit will blacken the inside with black paint to avoid unwanted reflections.
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