Some of you who know me will find this acquisition somewhat surprising. The opportunity to buy this unit came rather suddenly, after some other used 'scope deals and home-building projects never got off the ground.
I was already stuck in the "SCT vs. Big-Dob" dilemma. Hoping to get into CCD work some day, I was coming very close to ordering a 12" LX-200. There's a bit of a story about how I wound up with this instead; if you ask me in person, I'll tell you about it.
So the JMI NGT is, as I see it, a great compromise scope between a Dob and an SCT. It's like a little of both. It's a 12.5", F4.5 truss-tube newtonian on an innovative split-ring equatorial mount. It has R.A and declination drive motors. And it's all metal (with a bit of plastic) -- there's not a splinter of wood to be found on it. The mirrors are made by Nova Optical Systems, with enhanced coatings by QSP.
I took delivery of it yersterday morning, just in time for the trip to Lassen. No, I won't be held liable for adverse conditions at Lassen attributed to this acquisition -- other people are bringing new gear as well!
Last night, I set it up out on my sidewalk, under the orange street lamp, in the shadow of a small tree, with canyon-like horizons. I did a rough polar alignment using a (magnetic) compass and by setting the calibrated latitude scale from a topo map.
The only bright, quick, and easy objects I could see from that location were Alberio, M13, & M57. The sky was bright and hazy, and the city lights reflected off clouds in my only window to the extra- terrestrial. From my north San Jose home, the seeing basically wasn't.
Alberio and it's partner, at 158X, readily separated even though it looked like two hazy, colored blobs. M13 at 53X was as bright and clearer than in the SJAA-owned 13.1" F4.5 Coulter Oddyssy I've been using recently. Stars showed less coma in the JMI than I've become used to in the Coulter.
Under last night's conditions, I knew that seeing more than a recognizable blur on M57 would be unlikely. I could just make out it's ring-ness at 53X, and last night's poor contrast made it a more difficult object at 158X. But I had another test in mind that didn't really involve the optics: I wanted to test the drive and the stability of the mount.
Getting the ring nebula carefully centered at 158X, I went for the absurd 476X view. A fuzzy, low-contrast blob, vaguely hollow, almost filled the field of view. Adjusting the crayford-style focuser caused no image shift, and resulting vibrations were damped almost as soon as I let go of the knob. It was easy to get close to the eyepiece without disturbing the view.
I set a timer to beep at 6 minute intervals. My goal was to see how much the image drifted in the 30 minutes of a typical film exposure. I had to make one declination adjustment at 21 minutes into the test, which was less than 20% of the eyepiece field of view. But even without that adjustment -- the ring would have stayed in the eyepiece for the entire half hour. That's much better than any other mount I've ever had in my posession.
I've heard a lot of rumors about collimation problems with the JMI 'scopes. So I took it back inside and played both with a cheshire eyepiece and a Kendrick laser collimation tool. I couldn't see any error in the Cheshire no matter how I rotated the secondary assembly. The laser collimator showed a little error, however. There was less than a beam's-width error in the spot where the laser hit the primary, but back at the scale on the collimator, It was nearly impossible to keep the beam perfectly centered throught the roation of the secondary assembly. However, I should say that the none SJAA Dobs I've borrowed held collimation this well -- from just movement in the altitude direction. I'll see if this becomes an issue under actual use.
I'm looking forward to testing this 'scope under darker skies, and to see what I can get on film with it. I'm excited about this new instrument, and I hope some of you joining me at Lassen can help me get the most out of it.