I wanted to update the blog since the last few depressing posts. In late December, I took the AP1200 mount partially apart -- specifically the RA gear and worm sections so I could regrease the gears. I was getting so discouraged by the performance of the mount that I thought I was sold a lemon. I worked with George at Astro-Physics to get missing screws for the motor covers. He also had me update the hand controller which had a whiny buzzing sound. I applied DeOxit D5 to the internal connections that had unpluggable wires. This reduced the buzz by about 75%. It's still there, but it's minimized.
I ordered some gear grease, Aeroshell 33 MS, from a gentleman on the Astro-physics Yahoo list who had acquired a bunch of it and wanted to get some out to the public. I don't know how old the older grease was, but it was this gooey green-brown gunk that was obviously applied way too thick. There was tons of excess grease in the corners of the gear boxes and around the edges of the worm and RA gear. I spent 3 nights with a pile of cut up t-shirts and toothpicks to get the worm and RA gear clean. It took a lot of work and I found that the old gear had sand/grit in it, plus the grease had become partially solid in the deeper parts of the teeth in the worm and RA gear. A lot of pressure with the toothpick was needed to get the gunk out. I also found that the housing that protected the RA gear was pasted with grease on the inside. But I really couldn't get at that housing without doing a much more serious tear-down of the mount -- which scared me. So I merely took long strips of paper and fed it in the space between the RA gear and the housing and did the best I could. Lots of old grease came out -- along with sand and grit. But I knew there were sections that I coudn't get to.
Hm..... Anyways, I applied the new grease very lightly so as to coat everything possible in a very thin application. I could tell when I re-meshed the gear and worm that it was a better fit. I worried a bit thinking that maybe the previous owner applied a ton of grease to hide some RA gear defect. In a close examination, I noticed that there was some noticeable RA gear wear that corresponded to when the mount had the OTA near the bottom -- right before the point that a pier collision was about to happen. I suspect I was seeing minor gear wear/damage resulting from numerous pier collisions.
At this point I could have done the Dec Gear and worm, but I wanted to test the results of my work.
Previous to the regrease, I was getting around 1 to 3 arc sec RA guiding in PHD2. After the regrease, it improved to about half the guiding error (.5 to 2 arc sec guiding). It was an obvious success. But I also noticed weird stuff. When the mount was WEST heavy AND the scope was on the east side, it guided especially well. On the East side - regardless of the balance, the guiding got worse. I also noticed that most of the time, the DEC guiding was consistently worse than the RA guiding which makes me think I need to go back and regrease the DEC gear and worm. There should be an improvement.
So in other news, I picked up a Tak130D in a fit of madness. After spending 4 nights with the TAK130D and my recently modded Canon 6D, I came away feeling disappointed and disillusioned.
The Tak130D is a fast (F/3.3) reflective astrograph. The specs indicate a well-corrected field out to 44mm partly due to the custom hyperbolic mirror and corrector. I found that with the 6D, I only really had about a corrected field to maybe 30mm. The stars turn into cresent shaped blobs on the edges of the right and left sides. But well before that point, they lose their sharp, spiky shapes. The center area (maybe 12mm) is extremely sharp. But there is a noticeable deterioration after that.
I now know why Dennis DiCicco recommended that it would be a good telescope for a APS sized camera. There is a well-known review by William Castleman, self-declared expert on all things, who posts images that seem to be full-frame shots showing good correction to the edges. But my 6D shots reveal that either: a) Castleman actually cropped but "neglected" to mention that; or b) Castleman fixed the image in post-processing without mentioning it; or c) my Tak130D is a poor sample; and/or d) something is wrong with my 6D (see below).
I was really hoping the Tak130D would prove to be a cheap-man's FSQ106. But it's not by a long shot.
Anyways, I took 4 nights of shots with the Tak130D and 6D combo and found that my dumb modification to the 6D may need to be revisited.
This is about 40x3 min frames. But what sucks is that this only about the central 1/3 area of the frame. The actual area looks like this:
The awful vignetting is from a Astronomik UV/IR filter that sits above the sensor. So many challenges, so many issues. Meh.
I also gathered about 40 x 10 min exposures, but for some reason, Deep Sky Stacker doesn't want to process the images correctly. I've tried for several days with lots of different settings. It just doesn't work. It's frustrating to take so much data and not be able to process it.
In any event, I'm reshooting the area with the Tak102 and the Canon T3i. I've shot about 35x10 min frames. I want to double that to see if I can get more of the faint IFN nebulosity which is hinted at in the the first image above.
No comments:
Post a Comment