Sunday, November 22, 2009

Piggyback mount

Get your mind out of the gutter! I posted a year or so back regarding my refurbishment of my Meade 465 Newtonian telescope, a long, involved process made even more long and involved by my obsession with detail, due no doubt to daddy issues (relentless criticism of project flaws will scar a fellow for life, I tells ya). With my telescope in serviceable order, I've begun thinking more about astrophotography, which I've attempted off and on for more than 30 years with varying degrees of success. I mentioned earlier this summer that I was beginning construction of a home-built Piggyback mount, which would allow me to attach my Canon XTi (or The Wife's 50D) to the tube of my scope and let it ride "piggyback" for long-exposure tracking shots.

Now, most of the astrophotography I've attempted has been through the telescope, either "prime focus," in that the telescope itself is used as a large mirror lens (f/5 fixed aperture, 762mm focal length I think), and also "eyepiece projection," in which an eyepiece is inserted between the camera and mirror to project a magnified image onto the camera's sensor. Those are great for Deep Space Objects or planetary photography, but some sky elements, such as constellations, the Milky Way or Banard's Loop are so large they won't fit in the field of view. Because they're faint, they benefit from long exposures, which means tracking is necessary. Hence, piggybacking a camera on the scope is an ideal solution.

Well, after I started this project in June, I set it aside after cutting and drilling the block of wood that would serve as the piggyback base. I'd bought the screws and cinch to attach to my scope, but that's as far as it went. As these things are cyclical, yesterday I pulled out the supplies for this project and sanded the block down and puttied in many grooves and imperfections of the wood, then sanded it smooth. Today I layered on several coats of primer, sanded it down once more, then applied several more layers (stopping only because the can of primer emptied). After a suitable drying period, I sanded it smooth with 600 grit paper. I have to say it's not perfect--there are still imperfections--but I decided to rein myself in and say "close enough" is a better allocation of my efforts than obsessive perfection. It is pretty darn smooth, however, and once I start layering on the Claret Red Metallic tomorrow--I've got two cans' worth, matching the color of my scope--I'll wager that few people will be able to recognize the humble 2x4 origins of the base. The mount could reasonably be finished by Thanksgiving, but realistically, I'm shooting for the first of December, considering all the travel and other demands on my time I'll be facing over the next few days. Still, the thought has me excited. I expect good things from my EF 50mm 1.8 mk I lens, or The Wife's Tamron 28-75mm 2.8. Both are very sharp and fast, and should excel at starfields and big, faint objects like the North American Nebula and Banard's Loop. We'll see. Winter has some of the best astrophotography targets, and if the weather cooperates, I'll share my efforts here.

Now Playing:

No comments:

Post a Comment