Photos Made Using Barndoor III David Cortner
Fifth Night: The only thing I want to shoot tonight is fresh hydrogen-alpha data to complete last night's image of Cygnus and the northern Milky Way at the end of the season. For that, I'll shoot from the backyard with Cygnus near the zenith. An hour after sunset ought to do it. I'll use the Hap Griffin modified 20D and rescale the image to match the 50D photo I made last night. Then we'll see if I can sweeten the emission nebulae that dominate the central plane of the Milky Way. Today I put a longer drive bolt on the mount and turned a beautiful shaft coupler from some soft aluminum. The phrase, "machined like butter" came to mind. It was gorgeous right up until I drilled it for the set screw to hold the 3/8 drive bolt. I drilled too close to the end of the coupler and broke through, leaving some nasty looking edges. I drilled another hole some distance back and about 45 degrees away, which seems to work fine. But it's ugly. And I trimmed the length of the acorn nut to buy a few more minutes of tracking. Buggered the threads, then drilled them out and epoxied the nut in place which took back all the advantage of shortening the acorn nut. I had no spare and the skies were clear, so I made do. All this will be cheap and easy, albeit a bit tome-consuming, to redo if I decide it's just too ugly. It is, and I almost certainly will redo this part of the project. But the mods do what they were meant to do: the mount will now track twice as long (or longer) than it would last night. I got in 2, 10-minute exposures of Cygnus in H-a before thin clouds began to drift through. Frankly, I'd rather sleep than collect marginal data tonight. Here's the best effort at sweetened Cygnus:
Yesterday's frame + 2 x 600s through 7nm Baader
H-a on Glowing sodium from streetlighs and glowing hydrogen among the stars. The H-a data would dominate the frame if I displayed it at full saturation, so I've "thinned" the overlay greatly to preserve some semblance of a natural sky. Natural to an owl, perhaps, an owl with great color perception and extended red sensitivity. It's still not trivial to map one image onto the other. "Registar" may have a customer in me yet.
Later that same night: I realized I had a lot more data to use. I added a second frame from October 20. That (and a little blue boost) muted the cloud-glow and enhanced stars. Unfortunately, that also muted the H-a data more than I would like. We'll try this again with cleaner data eventually.
All with 17-85mm Canon @ F5:
October 22: Felt really lousy most of the day and gave myself most of the day off from the web and stocks and estate stuff and banking and email. Lord knows what will be waiting tomorrow, but today I spent a couple of hours in the shop. I made a new coupler (you knew I would), and this one is beautiful: one set screw holds it to the motor shaft, two set screws, 90 degrees apart, hold it to the drive bolt. Clean and pretty. The bolt is held solidly, straight, and has more available lift than the first version but less than yesterday's messy version. Plenty. I cut the epoxied-on and over-bored acorn nut off and replaced it with a regular chromed acorn nut that I found hiding on my desk. That's all fine, but I'm still not shooting anything tonight. I'm just getting some rest.
|
