4/24/2010 Something old,
something new. About seven weeks ago, I was enthusing about
Astro-Physics mounts, saying that I eventually wanted to put one
under my telescope, that the mount needed to be able to support my
current telescope as well as the larger telescope I expect A-P to
build for me
Over the last couple of years, I've become frustrated with the hit-and-miss performance of my older imaging rig. It was chock full of small, unreproducible anomalies. My mount was a Losmandy G11 (circa 1992), a solid, capable, but somewhat idiosyncratic piece of hardware. Among experienced astro-imagers the G11 has a reputation for "value."
"Value" means that while it costs a fraction of what mounts with similar capacity cost, you'll need to tweak, adjust, and otherwise rework some aspects of the mount to get its best performance. It will require time and care to put it right and careful setup to keep it right. Mine is equipped with the original stepper-motor controller which renders it incompatible with autoguiders using the now-ubiquitous ST-4 protocol. While it can still be autoguided, the feat requires a chain of adapters and computers and software that are themselves complex enough to introduce mysterious problems from one night to the next. Setting up and taking down takes time. And a substantial fraction of every night's results has to be discarded owing to slight guiding errors that too often render stars slightly oblong rather than round.
Laudably, the G11's maker, Scott Losmandy of Hollywood General Machining, supplies a retro-fit kit that would allow my vintage G11 to be upgraded to the latest specs: servo motors, go-to controller, and ST-4 compatibility. For about $1,800, a "Gemini Level 4" retrofit with heavy-duty motors could bring my 18-year old mount up to date. The Gemini system works reasonably well. It has its fans, and it has its detractors. I've thought about doing this for a couple of years. In the end, I almost always decided that the end result would be a less idiosyncratic imaging platform, a large improvement for my current telescope, but probably marginal for my next telescope. After the work and expense of upgrading, I was sure I would be left wanting more.
Look: Scott Losmandy builds motion-control rigs for the motion picture industry -- tracks, cranes, mounting hardware for cameras that are worth far more than my mortgage. He also builds medical bracketry. When you sit in the dentist's chair and note the single pole carrying trays, X-ray machines, drills, electric spittoons and lights, you may be looking at some of Scott's work. Scott uses the same CNC machining that turns out these mainline products to build telescope mounts and accessories for amateur astronomers. Noting that they are his sideline is not to say that they are slipshod or built with insufficient attention. Losmandy's dovetail rails and rail-mounted accessories are well respected and come as close to defining "industry-standard" as anything in the hobby. But it is to say that the reputation of Hollywood General Machining does not ride out the door with every telescope mount. One could argue that controlling telescopes to sub-arcsecond accuracy is an order of magnitude more demanding than aiming a Panaflex camera at Johnny Depp or Renee Zellweiger, to say nothing (please) about the demands of holding a spit basin for your dentist. There's precision and then there's precision.
Roland Christen's company, Astro-Physics, Inc., of Machesney Park, Illinois, makes telescopes and telescope mounts. Only. If in any gathering of amateur astronomers anywhere in the world you were to declare that A-P makes the best mounts and the best telescopes on the market, you would probably get an argument. Takahashi, Software Bisque, TEC, RCOS, and a handful of others have their devotees. No one, however, would think the claim was without merit or wrong-headed. It is plausible; it might even be true.
Something new. So there I was In March 2010, once and for all sourcing and pricing Scott Losmandy's Gemini upgrade for a G11 mount that was old enough to vote. I was dithering about whether to hold out for a vendor who could supply the higher-torque Maxon motors rather than the lower-power standard motors. Then I noticed that A-P had some mounts available for immediate sale. This was decidedly unusual. Usually you express interest in an Astro-Physics product, wait several months (sometimes years) for the chance to order it, and then wait some more until it is built, tested, and delivered. Increased production capacity and a strained economy combined to leave a few mounts from the current production run unspoken for. At least a few people who had expressed interest a couple of years ago found themselves out of the market when offered the chance to put their money down. When that happens, A-P announces via their website that new mounts are available without a notification list. Anyone can call dibs in exchange for an immediate deposit of 50%, the remainder due before delivery. Tagging onto the end of a production run can get you a mount in weeks instead of years. The only downside to A-P mounts (a downside shared by all high-end mounts) is that they cost like a sunovabitch. I told Amy how much. "Well," she said, "Why don't you just buy one?" After 12 years, I sometimes know when to stop talking. I rinsed the dishes, baked a chocolate espresso cake, and ordered a telescope mount. I didn't mention it again until a few days before UPS delivered it.
My new mount is a A-P Mach1GTO, a name which reflects Roland's taste for hot rods and American muscle cars (the GTO in the mount's name is short for "go to," a computerized aspect of the mount that allows it to automatically point the telescope toward -- "go to" -- any of several thousand objects in the sky or to any specified celestial coordinates).
The Mach1 is smaller than the 900GTO I always thought I wanted to put under any future telescope, but a cold comparison of the Mach1's and 900's specs and prices, a sober assessment of my realistic future needs, and the availability of the Mach1 now pursuaded me that the smaller mount might well be the mount for me. The 900 is appropriate for the telescope I would like to have someday, but it is more than I need for any telescope I actually expect to own. The 900 would be my first choice if I lived Out West under dark skies, where I could put it on a pier under an unobstructed firmament. But I have to count on traveling to The West from time to time and on dragging it around my backyard to dodge trees that neither I nor our HOA want cut. I found photos and testimony that it would carry anything I could expect to afford. Besides: if I could ever afford anything bigger than the Mach1 could carry, I could probably also afford a bigger mount. The Mach1 and the 900 use the same motors and the same electronics. The 900 is said to be "portable," but the Mach1 is casually portable. It's also a few thousand dollars less expensive.
Only two issuses arose while putting the new mount into service. First: I'm sure the adapter for the polar alignment telescope works perfectly well for recent Losmandy alignment 'scopes (Scott's popular and effective polar alignment telescope is another "industry standard" established by the G11), but mine was made in 1992. It was part of the very earliest shipment of Losmandy G11's, the ones commissioned and sold by Celestron, and it was just that smidgen too large to fit properly in A-P's adapter. I chucked the tube of the alignment telescope into a lathe and turned 0.045 inches off part of its aluminum barrel. Now it fits. Second: when I ordered the adapters to mate the mount to my Losmandy pier top, I misread the parts' descriptions on A-P's website and failed to understand that I needed two different adapters rather than just one. I confessed my mistake via email to A-P on Wednesday afternoon; the part went out 20 minutes later. It arrived Friday morning via UPS 2nd day air in time for me put the mount through its paces over the weekend. In addition to its telescopes and mounts, A-P is famous for customer service. Rightly so.
Something old. The telescope is one of Roland Christen's earliest: a 5-inch F6 triplet made in 1986. I bought it in 1993 from its original owner, Larry Price of Albuquerque, New Mexico, via an ad in The Starry Messenger. Larry had advertised it a few months before, when I was still waiting for ETSU to decide whether to hire another systems analyst and, if so, whether to hire me. Larry, I thought, did you have to advertise this now? One afternoon some months after I got the job, I walked home from the university, found the new issue of TSM in my mailbox, flipped to the "refractors" section, and saw that Larry was once again advertising my telescope. I walked straight to the telephone before even dropping my book bag. I asked Larry if the telescope was still available. It was. I said, "Then I think you should sell it to me."
From the sublime... Agena Astro Products makes available some good-quality products at bargain prices. Agena is a small company in Cerritos, California, which imports off-the-shelf hardware from Asia, resells it, and ships it (usually prepaid) instantaneously. From Agena, I bought a GSO 2-speed focusser for my guide telescope and a crosshair eyepiece. Forget ten years (and counting) waiting for an A-P refractor. Never mind seven weeks for a "no waiting" mount that someone else had already waited 2 years for. I waited less than 72 hours between clicking "Buy it now" and opening the boxes from Agena.
This is the alpha and omega of astronomical cachet. The focusser, the eyepiece, the mount, and the telescope are all lovely. I like state of the art, but more than that I like things that work.
The focusser replaces the stock focusser on my Orion 80mm short-tube refractor. The ST80 rides on top of the A-P refractor as a guide telescope. A digital camera watches the stars through the 80mm refractor. If they wander even a fraction of a pixel, autoguiding software signals the mount to move so that the stars go back where they belong. The new focusser fits the same tube, uses the same holes, uses the same screws as the rough and not-so-ready stock focusser. It took five minutes to install. It provides a more precise and solid platform for the guide chip. That's no small matter: if the stars wander on the guide chip owing to a loose or flakey mechanical connection, the guider's commands introduce tracking errors rather than correct them.
You pay dearly for razor-sharp optics and a precision mount, but you put all their benefits at risk if the autoguider does not ride securely behind the guide telescope. The GSO focusser insures that it does. The GSO focusser has an engaved scale. You can preset points of reasonable focus for guiding and for visual observation. That means that the guide telescope can serve as a finder to locate stars in daylight and in twilight so the Mach1 can be polar aligned before full darkness falls. After the mount is aligned, the same scales help to return the guide camera to proper focus. Each step saves time. You do not want to spend time and money to put yourself under clear, dark skies only to squander otherwise useful hours preparing to make a photo. Better to be ready to go when the sky is dark. A $100 GSO focusser and a crosshair eyepiece help make the most of an imaging system worth 100x as much. That makes them steals.
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