Sunday, January 11, 2015

 

Deforking Bertha


The 64 thousand dollar question for 2015 was, as I told y’all in the New Year's blog entry “What do I do about the C11?”  I’ve had a NexStar 11 GPS since 2002, and I’ve loved her for most of that time, though we got off to a somewhat rocky start, muchachos. When she arrived at Chaos Manor South a dozen years ago, the NS11 skeered me. I was daunted by the size of an 11-inch Schmidt Cassegrain Telescope on a huge fork mount. How in the h-e double L would I get that thing on its tripod, even in alt-azimuth mode, without destroying it, my back, or both?

Turned out not to be as bad as I feared. Unk hadn't yet hit the big 5-0 and was reasonably healthy and strong. While I considered the purchase of Starizona’s Landing Pad tripod accessory to help get the scope properly positioned on the tripod, I soon decided I didn’t need it. With a little practice and the aid of a wheeled JMI case, toting the scope out to an observing field and lifting it onto the tripod was, if not easy, not as much of a challenge as I was afraid it might be.

And, so, it was unicorns and rainbows for me and the NS11, who I soon discovered was named “Big Bertha,” for quite a spell. For ten years. As my fifties ran out and my sixties approached, however, something strange happened. Every fraking time I took Bertha out, it was more difficult to lift her case into my vee-hickle and more difficult to get her up on her tripod. That danged CAT was putting on weight!

‘Course the problem was not the scope, but moi. Each passing year made wrestling with Bertha more of a pain. The result was that I stopped using the scope at our local dark site, reserving her for Chiefland and (occasionally) the Deep South Regional Star Gaze. Three years ago, following an incident where I nearly hurt myself right bad while maneuvering the NS11 in her case down the front steps of the old Chaos Manor South, I began using the scope even less. Once I purchased my Edge 800/VX rig in the spring of 2013, I stopped using Big Bertha altogether.

Which was a shame, since she is such a capable telescope, both visually and for video. I never did much long exposure astrophotography with her; that required hefting her onto her wedge, which was a hell of a job even in my salad days. She could do amazing stuff with the Mallincam Xtreme, however. The countless tiny galaxies of the Herschel Project fell before her like dry leaves before the wild hurricane fly. I missed those crazy deep sky tears down CAV way with my girl Bertha, but what could your broken down old hillbilly of an Uncle do?

As 2013 segued into 2014, I determined to do something to get Bertha back on the road and under the stars again. Thinking part of the problem was the big, heavy JMI wheeled case, I tried a couple of case alternatives. Which were dismal failures. I did develop an easier method of getting the scope in her case into and out of my Toyota 4Runner, but it was easier, not EASY. Leave Bertha caseless? That was harder, not easier. At least I could roll her to the scope in the JMI. Regretfully, I put Bertha out to pasture again.

Oh, how I missed having the C11 on the field with me on those nights when I decided to go visual. Yes, a C8 like Emma Peel, my Edge 800, can do a surprising job on the dadgum faint fuzzies, but come close to a C11? No freaking way, y’all. There was simply no question of me continuing with Bertha the way she was, though. In the course of cleaning out the Old Manse after our move last spring, Unk took a spill and fell on his back on the front steps. Didn't do any permanent damage, but I was stove up for a long time. That little accident underlined that I have to take things easier these days and be more careful, and that precludes waltzing a 66-pound fork mount SCT around.

The all too obvious solution, then? Bertha would have to come off her beautiful fork and go onto a GEM, a German equatorial mount. I hated to do that. Not only were her gotos always spot on from one side of the sky to the other, in alt-azimuth mode she was incredibly stable. And her GPS alignment (I never upgraded to a new hand control) made getting aligned the work of three or four minutes at most. But ‘Twarn’t nothing for it. The fork was the trouble and had to go.

Resolved to defork poor Bertha, the question became “And put her on what?” I considered that for months. I ruled out the expensive solutions, the Astro-Physics and Bisque mounts and the others in that tier. I wanted to do the same things with Bertha on a GEM that I’d been doing with her on a fork: deep sky video, planetary imaging, and visual observing. Any of the high-toned GEMs would be overkill. And Unk is thrifty to a fault these days.

At the top of my list for Bertha was Losmandy’s venerable G11 mount, now equipped with the new Gemini II goto system. After setting up next to a dude using one at last fall’s Deep South Regional Star Gaze, though, I changed my mind. The G11 seemed a mite on the large side for me with that big tripod, and while the Gemini II system had some incredible features, it was, in my opinion, still a work in progress given the way my neighbor sweated over getting aligned and tracking during the star party.

What then? The next obvious candidate was iOptron’s innovative CEM60. This mount is a uniquely designed “center balanced” GEM like the company’s smaller ZEQ25. There’s a lot to like about the CEM60. Its base version (without external encoders) is less expensive than the G11, even when purchased with one of iOptron’s nice-looking piers. Certainly, its payload capacity, 60-pounds, would be more than adequate for Miss B.

Unfortunately, the more I read about the CEM60 on the cotton picking Cloudy Nights and the other astro BBSes, the more I began to believe it, like the Gemini 2, was not quite finished yet, either. In addition to people reporting various QA deficiencies, including some affecting mount stability, the CEM60 currently lacks a multi-star goto alignment, relying on an accurate polar alignment to deliver good pointing accuracy.

That would be something of a killer for me. If all I wanted to do was prime focus imaging, shooting two or three objects—at most—over the course of an evening, syncing on stars near the target and/or doing a little hunting would be acceptable. What I sometimes want to do, however, is image 50 or 100 targets with the Mallincam in one night. For that to happen, goto has to be bang-on every freaking time from horizon to horizon. I believe that, once it matures, the CEM60 will be a helluva mount and an excellent value. I just don’t think it’s there yet.

Well, well, well. What would I do? What would I do? Maybe I already had a GEM mount that would do. I am not talking about my VX or CG5. While I’d observed frequently and happily with my buddy Joey the K’s CG5 mounted C11 over the years, the big OTA is undeniably a handful for the VX/CG5. Not horrible, mind you, but doing video on a breezy night down at the CAV would not be easy if it were possible at all. Luckily, the CG5 and the VX are not my only GEMs.

I also have an Atlas (EQ6), which is a step up. And, its tripod is equipped with the TPI spreader system, which makes it very steady indeed. Replace the Atlas’ Vixen saddle with a Losmandy D type saddle, put a Celestron vibration pad under each leg, and I figgered the C11 would be Real Good on the Atlas. While the mount head ain’t exactly light, it is over twenty pounds lighter than the NS11/fork and less awkward (and dangerous) to carry around.

Only fly buzzin’ around in that-there ointment? The Atlas’ goto has always been fine, but never on a par with the excellent accuracy of the NexStar 11 GPS. The Atlas’ SynScan computer does feature a 3-star alignment, but pointing is still highly dependent on a middling-good polar alignment. Good goto with the Atlas also relies on you—not the hand control—choosing the best alignment stars. Even when everything is right, there may be problem spots, like the area near the zenith.

The Atlas’ goto could always be somewhat finicky, but its quality maybe got worse with the last firmware release for the mount, v3.35. Still more than adequate for prime focus imaging, but for running The Son of the Herschel Project? Probably not. These ruminations on my part concerning the Atlas coincided, however, with big news:  Synta/SkyWatcher had released a new firmware build for the SynScan mounts (which includes the Atlas) designed to fix multiple problems. It also promised improved alignment star filtering. Theoretically, you should now be able to just accept the first stars offered by the hand control—just like with the Celestron mounts.

I loaded up v3.36 and hit the backyard for some tests. The scope on the Atlas would be my venerable 1995 C8, Celeste. At f/10, her focal length would be comparable to that of the C11, which I usually run with an f/6.3 or f/3.3 reducer.

You might not believe it, campers, but Unk occasionally has nights when everything goes right. I polar aligned with the polar scope, using the value for Polaris Local Hour Angle on the HC to dial it in nice and close. I was purty sure this was going to be a good run when the second of the three alignment stars, Deneb, was in the field of the main scope’s eyepiece when the slew stopped. I centered up the third star, Capella, and starting issuing some goto commands.

Everything I requested, from M57 in the west, to M37 in the east, to Fomalhaut in the south, to NGC 457 in the north, to M31 near zenith was in the center of my 20mm eyepiece at 100x. I don’t mean “near the center,” I mean “dead center.” Being a suspicious sort, I returned to these objects several times over the course of the evening, and each was again centered.

As the clouds moved in and I hit the Big Switch, Unk was feeling good. While I had been careful with the polar alignment, that was all. I hadn’t picked special alignment stars, just OKed those the HC offered first: Vega, Deneb, and Capella. I believed we was good to go. All I needed to do was order a replacement “D” type saddle for the mount and a Losmandy style dovetail bar for the scope.

The next morning, I was still on a high about the way the Atlas had performed with the new firmware, but, as y’all know, your old Uncle often quotes the Gipper’s “Trust but Verify.” Sometimes that is for no good reason. Others? It can save the day. Since it looked like we’d get marginally clear skies for a while after sundown, I figgered I’ve give the Atlas one more go, just to be sure.

Didn’t do anything different on this evening. I set the scope up in approximately the same place in the backyard. I did notice when I was polar aligning that I had to move the mount in altitude. Why should that be? I put it down to “whatever” and pressed on. The HC came up with the same three stars as the previous evening. I accepted ‘em, centered ‘em, and got to work.

First up was M57. It was in the middle of the field of the 13mm Ethos I was using. M37? Not so much. It was in there, but off toward the edge. M31? Nuttin’ honey. It was not in the eyepiece. It was not even close to the eyepiece’s field. What the hell?

I started thinking about the polar alignment. Had I aligned on the wrong star? It was just barely dark when I’d done the alignment, and I’ve been known to do my polar alignments on Kochab instead of Polaris under those conditions. How about the goto alignment stars? It was earlier in the evening, and Deneb was up fairly high. Maybe too high? First thing I did was use the hand control’s built in AllStar style polar alignment routine. I wanted to see how well it worked anyway. I had to move a substantial distance, so it looked like my polar alignment had indeed been punk for whatever reason.

Polar alignment redo redone, I shut down and did a new three-star using Capella, Hamal, and Caph. Result? M37 was still toward the field edge, but closer to the center. Same for M31, thank goodness. Indeed, everything I slewed to before the night’s ration of clouds impelled me to pull that accursed Big Switch was somewhere in the field, but usually not anywhere close to the field center.  I broke out the Yell and watched a couple of episodes of Unk’s current fave cable TV show, freaking Bourdain’s The Layover, and decided to do no more thinking about the mount till the next morning.

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This was all beginning to weigh on your pore old Unk. I woke up with the fraking Atlas on my mind. And was still thinking about it as I drank my morning java. The theory I developed was that my initial less-than-sterling pointing was caused by that (supposedly) punk polar alignment. Redoing it helped some, but only some, because rather than using Vega, Deneb, and Capella, which were probably the best stars for that particular date and time, I picked three others. That was my theory, anyhow.

The elephant in the front parlor? While the Atlas’ goto performance with the new firmware can be sterling, it is still pretty obviously more dependent on polar alignment and alignment star choice than my VX or my CG5 are. For the sort of observing I had in mind, it was purty obvious the mount would always be a little too fussy. The VX or the CG5 take a little while to align, but there’s no hassle doing a goto alignment; you just choose the stars the HC comes up with. Polar alignment is never a factor with their goto performance.

“Well, then, Unk,” you might say, “why don’t you just use the EQMOD driver to run the mount. It will allow you to use as many alignment stars as you want and provide dead-on goto.” It will in theory. I’ve had varying success with it over the years, though I know many Atlas and Sirius users swear by it. Last couple of times out (the latest version of) EQMOD would not sync on some stars—which was likely pilot error. I don’t always want to tote a computer into the boonies, though, and even when I do, I don’t want to do anything with it other than just send the scope on her gotos. These days, your Old Uncle finds a hand control simpler to use.

I thunk and I thunk and I thunk, and it soon became evident the solution was staring me in the face and had been for a long time. I needed a larger Celestron GEM. Which one was easy to figger-out. I sure did not need the weight, payload capacity, and expense of the CGE Pro. The CGEM DX was a possibility, but the main difference between it and the standard CGEM now is a huge 3-inch legged tripod that weighs in at 50 pounds. I knew dadgum well I didn’t want to—couldn’t—deal with that. Which left the obvious, the CGEM.

The Celestron CGEM is based on the Atlas/EQ6 and has a similar payload, 40 pounds. The tripod is nearly identical to the one on the Atlas. The big difference other than some mechanical improvements and cosmetic updates? The Atlas’ stepper motors and SynScan handset have been replaced by servo motorss and the Celestron NexStar HC. Which was just what I wanted.

I talked things over with Miss Dorothy, whose opinions in such matters I value highly. She concurred:  get the CGEM. I picked up the phone and called one of my fave dealers, Bob Black at Skies Unlimited.  After a little checking, Mr. Bob found he had one in stock. All I wanted was to get the mount in time for our next Chiefland run, but despite New Year’s Day intervening, it turned out the mount would be in my hands the following Monday, or so the UPS goobers promised. Like all y’all, I want my new astro-stuff NOW, but a few days waiting was actually a good thing. There were a couple of things I needed to buy and there was some work to do.

First off, I needed a dovetail bar, a Losmandy D-type dovetail bar, for the C11 OTA. There are numerous sources for these, including Losmandy and ADM, who produce top-flight, beautifully machined stuff. As has been mentioned a couple of times already, howsomeever, your Uncle is Scrooge McDuck’s brother from another mother, and I didn’t want to spend a hundred dineros or more if’n I didn’t have to.

That in mind, I figgered I’d take a stroll through B&H Photo’s gigantinormous website. They (and Adorama) are my goto photographic gear folks, since they are renowned for their reliability, speed, and good prices. But did you know they sell lots of astro-gear, too? They do, and they had a Celestron D Dovetail for the C11 sure as shooting. For less than 30 bucks. Downcheck? It’s that modern Celestron Orange color, which some of y’all don’t like. Me? The dovetail on my Edge 800 is an orange one and I think it is kinda purty. Off to B&H went my credit card number.

What else? The finder mount that came with the NexStar 11 was an original Celestron non-removable job. Much like what came with my 1995 Ultima 8. To place the scope in the JMI case, the finder had to come off, so JMI provided a bolt on bracket and a new base to make the Celestron rings removable and reinstallable. Worked, but was decidedly non-standard. I went to my small-stuff guys, Agena Astro Products, and got another Synta SCT finder base on the way. Decent price and no shipping charge. Unlike a certain famous west-coast outfit who was willing to sell me the part for .25 cents less than Agena, but then wanted to tack on ten bucks to ship the tiny thing to me.

It was now time for the work. For deforking the NexStar 11, removing the tube from that big fork mount. I am no stranger to deforking C8s, older C8s, but this would be a decidedly different proposition. Not only is the tube of an NS11 comparatively big and heavy, its fork is buttoned up with plastic covers. I did some browsing on the web and reviewed a couple of folks’ instructions for DOING THE DEED.

Early one morning, I went out to the shop, manhandled Bertha out of her case, and went to it. You can hear and see the details in the video linked below, but to sum up? I padded the work area well with rugs and towels in case something slipped, and worked slowly and meticulously. Nevertheless, as you’ll learn in the video, it actually took longer to get the fork back together perfectly once the OTA was off than it did to take it apart (I plan to sell the fork, the JMI case, the tripod, and my big wedge on the Astromart soon, so I needed to restore the fork to its original condition).

With Bertha sitting on my workbench, all that was left to do was plug the screw holes that resulted from removing the fork brackets from the tube. Luckily, I had a bag of Celestron “place holder” (short, that is) screws. Once that was done and I’d essayed a little cleaning of the OTA, I gotta say Miss B. looked young again. The funky old fork was beginning to make her look like a relic from a bygone age. Now she just looks spiffy with her pretty carbon fiber tube and all.

There was one final piece to fit in the puzzle:  a dadgum case. I certainly didn't intent to continue hauling around that huge JMI container now that the fork was history. Luckily, once the fork is out of the picture, there are lots more options. The one your Unk exercised was, naturally, the cheapest:  a big Sterilite (Rubbermaid clone) container from Wally-fraking-world with some foam from their craft department for padding. Just over twenty bucks as opposed to more than a hundred for a custom C11 OTA case.

Finally, muchachos, I removed the old finder shoe, bolted on the new one from Agena (which arrived in two dadgum days), installed Bertha’s original Japanese finder (nice) in a Synta style ring mount which would fit on the new base. And began waiting anxiously for the mount. So, what happened when the CGEM arrived? That, my friends, is a story for next time, since we are plumb out of time and space for this Sunday.




Next Time: A CGEM Comes to Chaos Manor South...

Comments:
Just a note about the CEM60. It now has multiple star align with the HBX choosing four alignment stars for you or you can choose your own from their list of alignment stars should you have obstructions like trees or buildings. After aligning on four stars you can continue to align on as many stars or objects as you want. The one, two, and three star alignments are retained. Cheers - Dwight
 
Glad to hear that. Last word I had was that the multi-star alignment wasn't working and was disabled.
 
Ahhhh I got the CPC 11 deforked this morning, thanks for the short Video as it was a great help...

NSN Pat Utah aka. Alien Observatory
 
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