Telescope Reviews

Page 16 By Ed Ting Updated 5/21/02

Click on a Telescope Below: 1) Astro-Physics 10" Maksutov 2) Stellarvue 80 mm f/9 Refractor
1) Astro-Physics 10" Maksutov 4/13/01 (10" f/ 14.6 Maksutov-Cassegrain, OTA, case only, $9800) Life, it is said, is what happens to you while you're busy making other plans. Tell that to AP owner Roland Christen, who started this Maksutov project years ago. I first saw Christen's prototypes of the 8" and 10" Mak-Cass scopes at Astrofest in 1999. The views through the prototypes were very encouraging, to say the least. At that time, AP tentatively took orders for a few units, with expected delivery sometime in early to mid 2000.
The Big Mak in Action (Mount: AP900)
Christen's goal may have been to simply polish off a few of these while working on his other projects, but it wasn't so simple. Astrofest 2000 came and went, with little sign of the Maks. There were reported problems with coatings, and the figure of the mirrors was said to be less than what AP wanted for such an expensive product. The original goal was to produce 20-24 units, but by the end of 2000 scarcely half that number had actually shipped. This point illustrates the differences in philosophy between a small, quality-oriented company like Astro-Physics, and a larger one which might have more bottom-line pressures. Rather than ship out a merely excellent product, AP elected to wait until they were absolutely sure the scopes were to Christen's satisfaction. This philosophy results in the now-famous, years-long waiting lists for their telescopes. But there is a silver lining to all of this - you can go to bed at night knowing that when your AP scope does eventually arrive (the owner of this one waited 2 1/2 years), it will be perfect. I have never talked to an unhappy Astro-Physics customer. In my all-too-brief conversations with Christen on these Maksutovs, I could sense some hesitancy, and an element of frustration on his part. This turned out to be a much larger and ambitious project than anyone had forseen. What started out as just another AP telescope design turned into an all out assault on the optical state-of-the-art. I asked Roland about the design of these Maksutov-Cassegrains, and he suggested they were perhaps most similar to a Gregorian-Maksutov. "But..." he said, after a few moments of thought, "...not really." He suggested a new term, "Valery-Mak" after the owner of Aries Instruments, where the mirrors were sourced. But with all due respect to Valery, it seems that AP had to do enough refiguring and re- design of their own that we might now have a completely new telescope configuration.
The 10" prototype seen at Astrofest, 1999
So this Rol-Mak, Christ-Mak, whatever you want to call it, is now in very limited production, and a few of them have found their way into amateur's hands. I was most fortunate to have the use of one for a couple of months. The scope's primary is fused quartz and the corrector is BK-7. The mirror is tapered at its edges for faster cool-down. The secondary is an aluminized spot on the back of the corrector plate and is a tiny 2.3 inches (23% central obstruction.) There's an alternate secondary baffle supplied which actually increases the obstruction percentage, which is said to be of help during unsteady seeing conditions. While I had some unsteady skies, I couldn't bring myself handicap the scope in this manner and the alternate baffle stayed in its box. The machining of the metal parts is first-rate, as you would expect. The dew shield fits so tightly that I never even needed to use the set screw. The mirror cell is said to be turned and milled down from a 30 lb slab of metal. The end result is a cell weighing a mere 2 lbs (the other 28 lbs is recycled.)
The scope in its case
The scope arrives in a large trunk. It's surprisingly light (33 lbs) and compact, given its aperture and long 146 inch focal length. Two large straps help you muscle the OTA out of the case. You can mount this yourself, but it's best to have help. The Mak is designed to be used with an AP900 or AP1200 mount - there are aluminum blocks attached to the scope with small allen-head screws that mate up to the AP900/AP1200 flat plate. I used mostly the AP900 mount, but for high power observing I dragged out an AP1200 on a couple of nights with the help of friends. Mounting the OTA is a bit of a hassle in the dark. Those four allen heads never seem to want to find their corresponding holes on the plate, and it's all too easy to back the screws out entirely. When you hear that little "clink" of the screw hitting your driveway, you sigh and start over. We did eventually modify the scope to be used on Losmandy's Universal Dovetail Plate, which has a few quirks of its own but is much easier in the long run. I recommend this arrangement.
The flash went off in this photo. Note the complete absence of reflections off the meniscus lens.
Once mounted, you can breathe easier. What at first looks like a plain, fat, white tube is actually a sophisticated instrument packed with innovation. The coatings on the meniscus lens are simply wonderful. It looks practically invisible when you shine a flashlight into it in the dark; the secondary assembly looks as if it's floating in the air, and you feel as if you could just reach in and touch the main mirror. There are no collimation adjustments at all, which is just fine by me, especially since this one seems very well aligned out of the box. The focuser is a neat, and extremely smooth, belt-drive unit that moves the main mirror so precisely there's little or no image shift, even at 600X. A large shield fits snugly onto the front of the OTA, acting as an additional light baffle and a dew shield. There are multiple spots laid out for you to mount finders, and you will need them. Figure on at least two, and preferably three, so that one is always within easy reach. One big bugaboo of Maksutovs is their long cool-down time. There are two large chunks of glass inherent in this design, and a large column of trapped air in between them. To combat this, the entire back of the telescope is removable. You loosen three screws, give the back a twist, and off it comes. What remains looks like a skeleton. What's even more neat, there are two small pancake-style fans that help hasten cooling. There's a little jack on the back of the scope that takes AP's standard 12V connector. People seeing you remove the back of the scope for the first time sometimes get alarmed. It doesn't look right. But AP actually encourages you to do this, and you could actually observe with the back off, if you wanted to.
Cool, huh? The Mak with its back removed. Focuser is at lower right.
I am just enough of a geek that I like taking the back off and watching the belt drive on the focuser doing its thing. The focuser, by the way, is a multi- turn type, and you find yourself spinning it a lot to reach focus with differing styles of eyepieces. Some of us liked this, some of us didn't. On the first night with this scope, the temperature hovered around 0 degrees F, which is quite cold even for these parts. The scope seemed to have difficulty reaching equilibrium. Furthermore, when the OTA finally cooled down, so had we, and no one was in the mood for extensive testing. Being the enthusiastic dolt that I am, I tried to run some quick tests. Did I mention it was cold? It was so cold enough that inside of my nose had frozen; it hurt to breathe. And breathe I did, right through my scarf and onto the eyepiece, which promptly fogged up. I tried to look through the eyepiece anyway, only to touch the side of my nose to the cold, frost-covered 22 mm Nagler. The skin bonded instantly. Yeow!!! We decided to call it a night. Several weeks later, temperatures had risen to more reasonable levels, and we tried again. I set up a multi-evening event at my place, where local amateur astronomers were free to drop by, have a look, and offer some comments. The Mak was set up on the AP900, and I wasted no time in throwing everything I had at it - the AP155, the Takahashi FCT150, and the 10" and 11" EL Starmasters. The telescope has an excellent star test, with only slight undercorrection at high power. Collimation is excellent also, and the contrast is absolutely superb. Planetary detail is stunning given good conditions. In steady seeing, it beat everything else in the driveway on Jupiter and Saturn. It's a good sign when I can't wait to get the formal review stuff out of the way. Using this criteria, the Mak is a great telescope. I completely lost interest in reviewing it after the first half hour or so. I searched my memory for objects in the late winter sky until my mind went dry. Then I grabbed my Sky Atlas 2000 and started looking for obscure stuff. I ran some comparisons with the other telescopes. The Starmaster 10" EL matched the Mak on deep sky, but the Dob won't track at high powers like the Mak will, and the Mak is slightly better on planets. The AP155 and FCT150 were steadier more of the time on the planets due to their smaller apertures, but in times of good seeing the Mak put 'em away on low level detail. On deep sky the Mak beat the refractors all the time. The telescope has superb contrast. Even the dimmest low contrast galaxies in and around the bowl of the Big Dipper stood out from the black of the sky.
Looking into the visual back with the cover removed. Power switch and plug for fans are at 10 o'clock. Perforated holes mark locations of the cooling fans.
One side effect of a telescope with a 3708 mm focal length is that you are kind of boxed in to medium-high to high powers. So you can forget about looking at the Pleiades and other large extended objects. It felt strange using using 35 mm and 27 mm Panoptics as planetary eyepieces. The big Mak is perfect, however, for globulars, double stars, most open clusters, and especially planets. This high power/narrow FOV issue isn't much of an issue with me, but for balance I should state that a couple of observers felt closed-in, even claustrophobic, due to the scope's narrow FOV. As a result, they never really felt comfortable with it, and one person didn't like the scope at all because of this. However, the buyer of one of these will almost certainly have other telescopes that can do the low power/wide FOV thing. I set up the Mak next to the AP155 and the two were a perfect compliment to one another. In fact, as the weeks went on, I found myself actually liking the scope's narrow field of view. I used it to help hone my finding skills and never even bothered to initialize the Goto systems on either the AP900 or the AP1200. The Mak will reach focus with the AP/Baader binoviewer. You'll be twisting the focus knob a lot to move the mirror into place, but it's worth it. Using a pair of 32 mm Plossls, it's a real shocker on planets. One night I was in the garage looking over some charts and I heard a shout from outside. I thought someone might have gotten hurt in the dark. It turns out a club member had found his way to the Mak and was looking at a shadow transit on Jupiter (Click here to hear MP3 audio of someone looking through the binoviewer.) I used the same combination on Saturn and almost fell off my observing chair. Clavius on the moon stood out in sharp relief, with little pieces of the moun- tiantops seemingly hanging out in space in 3D. The Black Eye (M64) seemed to hang out there in space in front of a backdrop of pinpoint-sharp stars. The black eye itself looks like a comma-shaped area erased from the galaxy. Hunt- ing for obscure planetaries is easy with this scope - you just look around until you find the object in the field that isn't sharp. It is rare that I see a telescope sharp enough to do this even at relatively modest (100X-110X) powers.
A common sight in my driveway during March and April of 2001: The scope greeting the morning after a long nights' use.
Night after night, I found myself hoping it would be clear when I got home so that I could use this telescope. I looked for any excuse for us to be under the stars together. Although I used it on and off for two months, I still felt it would perform better given steadier conditions -- a scary thought considering how well it was already doing. Is this the "best" telescope in its aperture range? I have no idea, since the term means so many different things to different people. Suffice it to say, this is the telescope I would buy if I could. Highest recommendation. A telescope has not made me this happy in a long time. AP 10" Mak Hots:
  • Killer optics
  • Ultra-precise mechanics
  • Innovative cooling system AP 10" Mak Nots:
  • Expensive, needs good mount
  • High power, narrow field of view
  • If you don't already know you're getting one, you're not getting one The Verdict:
  • Stop presses: AP debuts killer mirror-based telescope! 2) Stellarvue 80 mm f/9 6/1/01, 7/21/01, 5/21/02 (80 mm f/9 achromat, equatorial mount, 25/15 mm Plossls, 1X finder) ($369 OTA, $539 w/ mount, new units are f/9.4) Another good value from Stellarvue. Vic Maris uses lenses of his own proprietary design, hand-selects the best samples, and spends time matching the lenses collimating the tubes. The end result is that Stellarvues cost a little more, but you are virtually guraranteed a good sample. Judging from the mail I get, Stellarvue's products and its customer service seem to be above average.
    The 80 mm f/9 Stellarvue
    In a move which is probably not fair to either Stellarvue or Vic Maris, I immediately measured to exit pupil of the scope and can report that this f/9 sample is operating at its full aperture (Click Here if you don't understand this reference.) The optics are very good, only slightly undercorrected, with about the level of false color you'd expect from an 80 mm f/9 achromat. There's a very light ring of purple around Saturn and a slightly brighter one around Jupiter. I've seen this scope many times over the past few months and have always been pleased with the views. I borrowed this sample from its owner for about two weeks. During that time, it was a fine compliment to other scopes that I had on hand. On one evening, I was curious if I could see all the M objects in the Virgo Cluster from my driveway. Before I knew it, three hours had gone by and I had logged dozens of objects. When you lose track of time, that's generally a sign of a good scope. By the way, all of the M Virgo galaxies were visible, although the dimmer ones like M91 were a little tough (I needed averted vision.) While a larger telescope like a 6" or 8" reflector will allow you to identify and study these smaller, dimmer deep sky objects, on a smaller scope like this one the most you can hope for is identification. Still, this isn't bad, and with persistance and skill you could get through a Messier Marathon with a small scope like this Stellarvue. The mount is your standard-issue unit from the Far East that's commonly known as the Orion Sky View Deluxe but is known by several other names as well. It's a decent mount for casual observing, but not really suitable long-term astro- photography. The eyepieces are generic Far East Plossls. While serviceable, you might want to think about upgrading them when you get the cash. I liked the large Red Dot finder, a kind of large-window version of TeleVue's Quik Point. Also, the focuser is a 2" unit, a nice luxury at this price level. Newer versions are f/9.4. Recommended for small achromat buyers willing to pay a little more for some extra attention. Update, 7/01: Stellarvue reports that new versions of this f/9 refractor use proprietary lenses of Maris' own design, which are said to be better than the conventional BK-7 glass used by similarly-priced small refractors. These newer versions use optics sourced from many suppliers. End Telescope Reviews, Page 16
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