Archive for the ‘SkyWatcher 90mm Mak’ Category


The lunar ‘Cheshire Cat’ revisited, and problems of contrast

November 3, 2014

2014-11-02 London moonwatching

Just a quick post before I head off to work. London has the telescope bug and he has a birthday coming up, so we were looking at various scopes on Amazon and other places. He wasn’t clear on the distinction between the three main telescope designs, so we hauled out the DK Universe book and looked at the ray diagrams the three kinds (refracting, reflecting, and catadioptric). He was familiar with refractors, like his 60mm Meade, and reflectors, like his Astroscan, but was less familiar with catadioptric scopes, which is not super-surprising since I’ve used my Maks hardly at all in the last year and a half, other than last year’s All-Arizona Star Party. The sky was clear and the moon was high, so we popped outside and set up my 90mm SkyWatcher Mak for a quick look at the moon. Astonishingly, I had not had this scope out in more than two years, since July of 2012.

2014-11-02 waxing gibbous moon - snapseed

Here’s my best iPhone photo of the moon from last night. Up near the top of the terminator you can see two glowing dots like eyes peering over the limb of the moon. If you click through to the full-size version, you’ll see that the eyes have a wide mouth below them and that one nostril is showing. Yep, that’s the lunar “Cheshire Cat”, which I first identified back in November, 2010. It was nice to see it again.

While I was processing that photo I noticed something alarming: a circle of glare around the moon that was bright enough to make the eyepiece field stop visible. It’s more apparent in this over-brightened version:

2014-11-02 waxing gibbous moon - light scatter

I was shooting through the Celestron 8-24mm zoom, just like Saturday night. Since I had a comparable shot with the same eyepiece through the C80ED from that evening, I dug out the raw photo and tried brightening it up to see how much glare would appear.

2014-11-01 waxing gibbous moon - light scatter

The answer is “almost none”. I used the same tool in GIMP (‘Curves’), and I brightened the image way beyond what I did with last night’s shot through the Mak, and the space around the moon is still pretty black in the C80ED shot. Not grey, as in the Mak shot. And this was only with tweaking the brights up, and not moving the darks down, which would be cheating since it would mask the problem.

It’s tempting to read this as a refractor-vs-Mak thing, but it might not be so straightforward. In this case the refractor has very good optics and coatings, so it’s near the upper end of what refractors are capable of in terms of control of stray light. But the Mak does not have fully multi-coated optics–this SkyWatcher version only has ‘coated’ optics, which means possibly as little as one coat of MgF2 on only the outer surface of the corrector. I have heard from someone (Doug or Terry, maybe?) that this particular model of SkyWatcher 90mm Mak has poorer contrast than the comparable but fully multi-coated Celestron C90–irritatingly I cannot find that post or comment at the moment, but I’ll post it if it turns up. Also, the C80ED has a long-ish dew shield which helps control stray light entering the objective, whereas the Mak does not; you can buy or fashion such things for Maks, but I haven’t taken either of those steps. Finally, I’ve seen some threads on CN about glare from the baffle tube in Maks and SCTs, so that’s another possible culprit here.

An informative test would be to pit the C102 against the Apex 127 on the moon, with a homemade foam or cardboard dew shield on the Apex to eliminate that variable. If I get time this evening or next, I may just try that.


SkyWatcher 90mm Maks sold out?

March 19, 2012

Seems to be the case. Amazon has no more, and neither do Adorama and OPT.

So what to do if you’re in the market for a little Mak? Get a C90, stat! As Ed Ting said in his 3-way Mak comparo, “An embarrassingly good telescope package for almost no money. As of this writing they’re practically giving them away. If you’ve been thinking about getting one of these, I urge you to do so immediately before they run out, or before Celestron stops making them.”

On one hand, there is probably little danger that Celestron will stop making them; they’ve had a 90mm Mak in their product lineup for almost as long as I’ve been alive. Now that the SkyWatcher brand has been subsumed into Celestron (both are owned by Synta), it’s likely that the SkyWatcher-branded stuff is being allowed to die off to strengthen the Celestron brand.

On the other hand, C90s have been around for ages in multiple guises, but they haven’t always been this inexpensive. I wouldn’t get one just because they’re cheap–that way leads to a garage full of telescopes–but if you already want a little Mak and you’re bummed that the SkyWatchers are gone, the well-reviewed C90 should be a more than acceptable substitute.

I haven’t posted any new observations with my little Mak in a while because it’s been raining here. Next weekend I’m out of town, so I was hoping to get out to the desert for a Messier Marathon this weekend. Naturally it rained all weekend and today dawned sunny and clear. So it goes.


The King of Planets courts the Goddess of Love

March 13, 2012

For the next few nights, Jupiter and Venus are going to be as close together in the sky as they’ll get this year. I took this picture this evening from my driveway with my old Nikon Coolpix 45oo, about a 1 second exposure. Jupiter is on the left.

If you have optics, even small ones, you should be able to see the moons of Jupiter and see that Venus is a half-lit D-shape instead of a round ball of light.

I was out for a bit this afternoon and again this evening with the 90mm Sky Watcher Mak. I am learning to live with the finder, and the scope itself continues to impress. This is one of the sharpest bird photos I have ever taken:

The seeing was better tonight than it has been in a long time. I put the little scope on Jupiter and dropped in a 6mm eyepiece for 208x. Jupiter was razor-sharp and zebra-striped with cloud bands. In the steadiest moments, the South Equatorial Belt showed a ragged edge, and a small white storm notched its southern border. It was one of the most mesmerizing things I have ever seen with a small telescope.

As always, I am amazed that a little hunk of metal and glass the size of a 2-liter bottle can do so much. I have really missed having a little Mak around, and I don’t intend to be without one again.


Sidewalk astronomy with SkyWatcher Mak 90

March 9, 2012

I took the little SkyWatcher Mak downtown tonight to do some sidewalk astronomy. I haven’t blogged about sidewalk astronomy in a long time because I haven’t done any in a long time. And that’s been bumming me out. I was away from it for too long.

I got started doing sidewalk astronomy back in 2009, as part of the global 100 Hours of Astronomy event during the International Year of Astronomy. It’s a pretty straightforward gig: take a telescope to a public space and give passersby free looks at stuff in the sky. The moon and planets are good targets, because people are familiar with them (not everyone knows what the Pleiades are), they’re naked-eye visible so you can point them out to folks, they punch through city light pollution just fine, and they look great in small telescopes. I know some sidewalk astronomers take big telescopes, and more power to ’em, but I have found that my inclination to go do it is proportional to the size of telescope I have to lug downtown (about five blocks from my house).

For the first long while, my sidewalk scope was my original 90mm Mak, the Orion Apex. It was perfect for the job: compact, lightweight, able to be set up and torn down in about one minute on either end, sharp optics, easy for newbies to focus… Then one night at an astronomy club outreach I reach out in the dark and turned the wrong knob on the mount, and dropped the telescope. On the way down it hit a tripod leg and my foot, but neither absorbed enough energy to keep it from hitting the ground pretty hard. The impact spalled a bit of coating (at least, and possibly some glass underneath it) off the primary mirror. I sold it cheap to a fellow amateur who thought it was salvageable.

My next sidewalk scope was another 90mm Mak, an old orange-tube Celestron C90. I had always wanted one, ever since I saw my  first telescope catalog back at age 12. They are sweet little scopes, build like tanks, and since they focus with a rotating barrel like a camera lens there is not much that can go wrong with them; if the focuser ever gums up you just unscrew the front part of the tube, re-lube the threads, and screw it back together.

It turned out, though, that I liked the idea of the C90 better than the actual thing (this was a far different beast from the modern C90 that is on sale at Amazon and elsewhere). The rotating barrel sounded good in theory, but in practice it was a huge pain to focus the scope while keeping it pointed at an object, especially at moderate to high powers, and especially for people with no experience. I used the C90 for sidewalk astro once or twice and then sold it.

(Aside: one of these days I’ll blog about the joys of buying and selling used telescopes. The bottom line is, scopes hold their value pretty well. If you are judicious and buy used you can usually sell them for what you paid for them, so once you’ve ponied up the initial investment you can essentially try out new [to you] gear for free.)

Then I went through a phase of doing sidewalk astro with bigger scopes: a 5″ f/7 reflector on a homemade mount, a 5″ f/5 reflector (Stubby Fats), and an 80mm f/11 refractor (Shorty Long). These are all fine scopes for showing people stuff in the sky, but not so hot for having to lug five blocks. I needed a dinky scope, something bigger than my 50mm refractor (which is too small for that kind of work) but smaller than my other scopes. Frankly, what I needed was a 90mm Mak, I’d just put myself in the position of not having one.

Until now. Suitably armed with the SkyWatcher Mak, I went forth into the warm spring night, and between 7:35 and 8:45 I showed 48 people the moons of Jupiter. The seeing was godawful, as bad as I have ever seen it. Jupiter was a visibly waving ball of fire, when normally I can see at least half a dozen cloud bands (as shown in the previous post). But the Galilean moons were all visible, strung out in a ragged line to the west of king of planets, and everyone who stopped to look seemed bowled over by the views, so who am I to complain?

I didn’t take the multi-mount that came with the scope, just the little Universal Astronomics DwarfStar alt-az mount that I used to use with the old 90mm Maks (shown in the picture at the top of this post). I left the finder and diagonal on the scope, put it nose down in the included backpack, put spare eyepieces in the side pockets, put all that on my back and carried the folded tripod and mount in one hand. It was great, just like old times.

John Dobson argues that the only measure of a telescope’s value that is worth a damn is the number of people who have looked through it. By that metric, I reckon this little Mak may end up becoming my most valuable scope. I’ll keep you posted!


SkyWatcher Mak 90–more pictures, and using the mount in manual mode

March 4, 2012

More pictures of the SkyWatcher 90mm Backpacker Mak-Cass. Yesterday I took the multi-mount off its tabletop base and put it on my Manfrotto tripod for some digiscoping. I was using it without the power on, as a manually-aimed alt-az mount.

Another of those down-the-tube shots showing the optics. The point of this photo is different, though. Check out the knurled knob on the left that tightens the dovetail. Usually these just have a fat set-screw that goes straight onto the scope’s dovetail bar, and tightening that screw puts a tiny dent or ‘bite’ into the dovetail bar. On this mount, though, the set-screw bypasses the scope’s dovetail bar, and turning the hand knob tightens a broad metal clamp (the silver bit just underneath the hand knob in the above photo) that grips the dovetail bar along its entire length. So the scope is held more securely, and there’s no bite mark on the dovetail bar. Very nifty–I wish more mounts had this.

The big news about using the mount manually is simply that it can be used that way. You don’t want to manually aim the scope once the power is on, or you risk damaging the gears inside the mount, but as long as the power is off you can just grab the tube and point.

A close-up of the back end showing, from left to right, the Astro-Tech dielectric diagonal and 32mm Plossl I was using for birding, the six-screw  mount for the little 8×20 optical finder, and the dovetail clamp and adjacent latitude/altitude scale on the mount.

Getting lined up on a distant bird using the optical finderscope. Imagine that the mount was sitting on its tabletop base and that you were trying to find something high in the sky–eventually there is just no room to get your head behind the eyepiece of the finder. That’s why I strongly prefer RACI–right angle, correct image–finders, which orient the finder eyepiece in the same direction as the telescope eyepiece, so you can look down and in from above.

Waiting for the fall of night.

My two best shots of Jupiter with the little Mak. I could see about half a dozen distinct cloud bands at the eyepiece, and for once the photos bear that out. As usual, however, I could still see more detail at the eyepiece than the camera captured. The views are not as good as through the Apex 127–compare to the Jupiter photo here–but they’re not that far behind.

The waxing gibbous moon, again with the little Mak. This is probably the sharpest moon photo I’ve ever gotten with a 90mm Mak. This SkyWatcher scope is at least as good, optically, as the Orion Apex 90 I used to have. I don’t know yet if it’s as good as the Celestron C90, which has gotten stupid-good reviews, but I don’t think it will disappoint anyone. Last night the sky was still enough that I could run it up to 200x and the view was still razor-sharp. That’s 57x per inch of aperture, compared to the rough rule of thumb of 50x/inch in a good scope, so this little scope is punching above its weight. I haven’t tried to max out the magnification to see where it breaks down, but I think it will probably be quite a bit higher.

The fact that the meniscus is merely coated instead of multi-coated has not impaired the scope’s performance as far as I can tell. Possibly the few percent difference in light transmission will be noticeable when one can switch back and forth between this scope and one with a multi-coated meniscus; it is certainly not noticeable when using the scope on its own.

I still haven’t had time to try out the tracking function on the mount, but this afternoon I did put batteries in and slewed it around and didn’t have any problems. I’ll report back when I’ve had it out tracking under the stars.


The SkyWatcher 90 Backpacker on the moon and some birds

March 2, 2012

Fate smiled on me yesterday and early this morning, and I was able to get some pictures with the SkyWatcher 90 mm Backpacker. If you’re impatient you can scroll to the bottom of the post for the photos.

I should stop here and say that I ultimately intend to test the whole kit–scope, mount, and accessories–as a system, because whether you use it as-is or mix-and-match components, it is sold as a system and is at least theoretically supposed to function as one. However, between teaching, taking a statistics class, and wrangling ostriches, I just haven’t had time to mess with the mount. My primary concern has been to assess the optical quality of the scope–and now I actually have some information.

I got in a brief observing session between responsibilities yesterday afternoon. I was plinking around the yard, looking at birds. For these observations I started out using the included 90-degree prism diagonal and 25mm Plossl eyepiece. I first looked at a couple of obvious birds silhouetted against the sky in treetops, and they looked fine. Then I went after one hidden in the leaves and branches of one of my neighbor’s trees, and in those dimmer conditions I noticed something unnerving: the eyepiece view was very soft and didn’t snap to focus, as if I was observing with a very short focal ratio scope like an Astroscan. Also, there was some ghosting of the image in the eyepiece, and the edge of the image was poorly defined. In short, it was very, very different from the crisp, sharp, detailed images that Maks are renowned for, and not in a good way. I was just having a “Hey, what the–!” moment when I remembered where I had seen these kinds of problems before: in scopes using cheap prism diagonals instead of mirrors.

Without moving the scope, I went to the garage and pulled the Astro-Tech dielectric diagonal off my Apex 127, and swapped that out for the prism diagonal. I held my breath as I put my eye back to the eyepiece–were the problems all in the diagonal, or had I gotten a lemon of a scope?

Sweet relief–even in the dim light amongst the leaves and branches, the view was razor-sharp and contrasty. It was like someone had run a very good image-sharpening algorithm on the eyepiece view. Suddenly details that were invisible before were popping out all over the place. Leaves that had been too fuzzy to invite close inspection were etched with delicate networks of veins. The whole view just looked more real.

I decided then that I would try to find out just how good or bad the prism diagonal is, and under what conditions.

After that quick peek I didn’t get another chance to use the scope until about 10:00 last night. The first quarter moon was still fairly high in the west, but the seeing was not good. The air just roiled over the moon, and every star I looked at scintillated with fast-moving rays of light. Not good conditions for testing a new telescope, because it’s hard to push the magnification up and tell if the results you’re getting are because of the scope, the seeing, or both. But I went ahead and put the scope through it’s paces anyway. The thing about seeing is that from time to time it does settle down a bit, at least momentarily, and in those instants the amount of additional detail that is visible is sometimes shocking. So the longer you look and the more patiently you observe, the more likely you are to catch those rare moments of steadier air and see something really remarkable.

For eyepieces I used a 32mm Sirius Plossl from Orion and the 12.5mm and 6.3mm SkyWatcher Plossls that came with the scope. I took all of the pictures in this post afocally with a Nikon Coolpix 4500 hand-held to the 32mm Plossl, and with the camera optically zoomed enough to eliminate any vignetting.

The moon looked surprisingly good with the Astro-Tech diagonal in place. It was fairly swimming in the turbulent air, as if being viewed under a thin stream of moving water. But if I focused on a particular crater or feature for the space of a minute or two I would catch a patch of calmer air and see perhaps double the detail in those brief glimpses. Small craters that were otherwise just spots would pop into focus with dark rims and bright floors. The 12.5mm eyepiece had tighter eye relief than I am used to in that focal length; I have long-ish eyelashes and they were occasionally brushing the eye lens, something I don’t remember ever happening with the 12mm SkyWatcher Plossl that I got with Shorty Long, my 80mm f/11 achromat. That 12mm looks identical to the Orion Sirius line, whereas the eyepieces that came with the Backpacker have smooth silver barrels and no rubber eyecups, so even though they are both branded SkyWatcher they might have somewhat different guts. Also, I’ll have to look more closely the next time I’m out, but the 12mm felt like it had a narrower apparent field of view than the 32mm, which shouldn’t be possible if they are both Plossls, which typically yield a 52-degree apparent field. Could be that the short eye relief was playing tricks on my perceptions. Anyway, with the 12.5mm EP in the scope was working at 100x and I was still seeing plenty of few detail in the still moments.

I put the 6.3mm EP in just for the heck of it. I wasn’t expecting much, both because of the punk seeing and because that magnification–200x–ought to be pushing on the edge of what this scope can do. A commonly used rule of thumb is that a good scope should be able to handle 50x per inch of aperture. At 3.5 inches, any of these 90mm Maks ought to be good up to at least 175x. But I have to point out that the 50x/inch “rule” is often broken and not only by premium scopes. David DeLano has had his 114mm reflector up to 400x (89x per inch), and the other night I took my Apex 127 to 514x (103x) to split a close double star that was not split at 257x. I’ll just note that those are both relatively long focal ratio scopes, about f/8 for David’s reflector and f/12 for the Apex, and maybe that has something to do with it; such gently-tapering light cones are certainly easier on eyepieces and so on. Anyway, at 200x with the 6.3mm EP I was still getting glimpses of considerable detail. I can’t say for certain because of the lousy seeing, but I think this scope can handle 200x. I hope I get a still night soon to test that.

Okay, so far so good with the Astro-Tech diagonal. I swapped it out for the stock prism diagonal and went back to the 32mm Plossl. YUCK! I almost could not focus my eye on the moon, because there was a moon-sized ghost image floating around in the field of view that looked like it was probably some kind of reflection of the primary mirror or maybe even the corrector. It was a big white donut with a dark hole in the middle, anyway. I’ll stress that this ghost image or whatever it was was not there with the Astro-Tech diagonal. I have never seen anything quite like it before, and given the controlled conditions of time, place, observer, scope, and eyepiece, I feel confident blaming the prism diagonal.

I tried the two other eyepieces. The ghost didn’t show up in either of them. The 12.5mm was merely okay, producing a slightly softer view in the prism diagonal than in the Astro-Tech. The 6.3mm was very noticeably softer; this time going from 100x to 200x looked and felt like empty magnification.

I also looked at Belelgeuse and Mars with all combinations of diagonals and eyepieces. Betelgeuse was sparkling in the Astro-Tech diagonal, but at least the scintillating rays of light were sharp. In the prism diagonal it was a fuzzy mess. Betelgeuse was down near the horizon, though, and Mars was very high, so I hoped to see at least some detail on good old Barsoom.

Mars really required the 12.5mm EP; at 39x it was a bright orange BB, too small to see detail on, and at 200x it was a big orange smudge. At 100x with the prism diagonal I could only suspect the polar cap, and that might have been because I knew it was there to be seen. I had started that run with the Astro-Tech, and in steadier moments the polar cap was a well-defined white patch with a hair-fine black border. In brief flashes I also saw dark markings on the face of the planet’s disk. So despite the lousy seeing, the little scope lived up to the Maksutov reputation as a fine planetary instrument.

I did see some off-axis glare from Betelgeuse and Mars, but only in the 32mm Plossl. I am going to do some more testing to see if that is a scope issue or, as I suspect, an eyepiece issue. Also, getting the scope on target using the 8×20 straight-through finder was not difficult but it was uncomfortable, and usually required me to move my chair, squat behind the scope, and go back and forth between sighting down the tube and squinting through the finder. It’s doable, it’s just not fun, and something like a 6×30 RACI should be a high-priority upgrade if you get one of these.

This morning before work I got some photos of neighborhood birds, using both the Astro-Tech dielectric diagonal and the prism diagonal that came with the scope. Be aware that that both my camera and my photographic method are primitive. The camera is a 4-megapixel job more than a decade old now, and while its rotating barrel design is convenient for digiscoping, it just can’t keep up with the better modern cameras. Also, hand-holding the camera to the eyepiece means that I’m usually the most mobile link in the system, so any fuzz or blurring in the photos is possibly caused by my minuscule shakes rather than by the optics. To try to eliminate that factor as best I could, I took several exposures of each target and picked the sharpest from each set for the comparison images. In all of the comparisons between diagonals, the photo through the prism is on the left, and the dielectric photo is on the right. Other than having been put into the same image for comparative purposes, the photos are completely unprocessed: no sharpening, no levels or curves, no rotation, and I didn’t even flip the photos through the star diagonal, which are reversed left-to-right. Click each image for the original, full-resolution version.

The moon last night. The view through the dielectric diagonal was markedly sharper and more contrasty, and these unprocessed photos, taken just minutes apart, bear that out. The full-resolution dielectric photo shows a very thin line of purple chromatic aberration around the limb of the moon, but I couldn’t see it at the eyepiece despite being on the lookout for it.

This fellow was sitting a tree that I have paced out at about 70 yards from my driveway. Again, the dielectric photo (right) has better contrast, and look at the difference in the color of the background sky. This is the same bird and I took the photos about 2 minutes apart.

This dove was quite a bit farther way. I haven’t paced it out, but this powerline must be well over 100 yards from my driveway. Notice the scale of the bird in the photos and the pronounced drop-off in detail compared to the little songbird above. Detail is probably a wash here, but the dielectric photo has better contrast and again the background sky is more blue.

One more point to make is that I hardly ever post raw images. Almost every photo can benefit from a little processing with Unsharp Mask and Curves (I use GIMP, which is free–see details on what I do to each photo in this post). Here are the best dielectric photos of the moon and the songbird, with the unprocessed photo on the left and the lightly processed version on the right (this time I did rotate the moon and flip it to its correct side).

So, what did I learn from all of this? The SkyWatcher 90 Backpacker is a decent little scope. I couldn’t see any optical problems, and I was impressed to see details on Mars at 100x with the included Plossl and the Astro-Tech diagonal. Views of birds are as good as those I used to get with my Orion Apex 90. But the supplied diagonal is not good, and really limits the views the telescope is capable of providing. If you get one, replacing the diagonal with even an inexpensive mirror diagonal should be a top priority. Let me put in a plug here for the Astro-Tech dielectric diagonal. It consistently throws up a great image–it’s the diagonal I used when taking the Apex 127 to 514x for that double star split–but at $69.95 for the 1.25″ version it is no more expensive than some ‘entry-level’ mirror diagonals.

The supplied prism diagonal does have one potential use: if you have an old binocular laying around, you can disassemble it and use one of the objective lenses to make a proper finderscope, and if you include the diagonal it could even be a RACI. Mounting a bigger homemade finder to the scope will take some ingenuity, but I figure anyone who likes to tinker enough to build a finder in the first place can be trusted to come up with a mount as well.

So I now feel confident enough to recommend the scope, at least, although the mount is still a question mark and the diagonal and finder are troublesome (as expected). I don’t know how the scope performs compared to the Celestron C90, which is also on sale, because I haven’t had the chance to test them side-by-side. But with a little luck I may get that chance soon.

Hopefully this weekend I’ll have time to get the mount up and running. Stay tuned.


SkyWatcher 90mm Mak unboxing

February 29, 2012

The Sky Watcher 90 mm Backpacker telescope that I ordered last week was delivered today. I wasn’t sure what all to expect in the box–the list of included items on Amazon is maddeningly unformatted and cuts off midstream. I thought I’d do a series of unboxing photos to document what’s in there for anyone who is considering buying this scope while it’s on sale.

Inside the usual plain-Jane shipping box is the actual product box with pretty pictures.

Inside that box are a backpack, the mount base, the warranty, and–yep–another box, all in their own plastic bags.

I was expecting to find the mount inside the backpack and the telescope inside the box, but I was wrong. The backpack contained the telescope tube–still swaddled in packing material in this shot–and the smaller boxes containing the accessories.

As with all the scopes I’ve bought new recently, the tube was wrapped in tissue paper to protect the finish, then cocooned in bubble wrap, then put in a plastic bag. Note the enclosed silica gel pack and “don’t blind yourself” warning tag.

Accessories, left to right: 90-degree prism diagonal (I was hoping for a mirror diagonal), 8×20 optical finder, and eyepieces. The eyepieces are 25mm, 12.5mm, and 6.3mm Plossls, all with silver barrels and stamped “Multi-coated”.

The back end of the scope, showing off the finish–which is insanely gorgeous–and the little descriptive plate with the scope’s specs. Note that the meniscus corrector plate up front is coated, not multi-coated or fully multi-coated (these are classes of anti-reflection coatings that improve light transfer through the scope; fully multi-coated is best).

Inside the smallest of the nested boxes: the mount, an L-bar adapter, the controller and cables. The L-bar was a nice surprise. Pictures of the assembled scope show the scope mating directly with the mount via its dovetail bar. The L-bar allows one to mount the scope upright instead of on its side, or to mount other devices with 1/4-20 mounting bolts, like cameras, binocular mounts, and other sport optics. Some thought went into the other accessories, too: there are a couple strips of sticky-backed Velcro so you can hang the hand controller on the side arm of the mount.

Everything set up, with an ink pen and the spare eyepieces (1.25″ barrel diameter) for scale. Note the leveling bubble on the mount. I was pleasantly surprised by the tabletop base. It looks plastic-y in pictures but it’s a nice big piece of aluminum with big rubber feet at the corners and a knurled hand-knob underneath for turning the 3/8″ bolt that goes into the bottom of the mount itself. That means the mount can go on any platform with a 3/8″ bolt, which includes most of the better photographic and surveyors’ tripods.

I had little time this afternoon and didn’t want to mess around with putting batteries in the mount and learning how to use it, so I put the scope on the Manfrotto CXPRO4 I use for museum photography and birding. This hall-of-mirrors shot is a typical view down the guts of a Mak. Incoming light passes through the meniscus corrector plate up front, bounces off the primary mirror at the back of the tube, then off the secondary mirror–not a separate piece of glass but an aluminized spot on the back of the corrector–then through a hole in the center of the primary mirror, then either straight into the eyepiece or, more commonly, off a mirror or through a prism that bends the light path by 45 to 90 degrees so you can look down to observe instead of crouching behind the tube to peer through it. The white dot farthest in is my ceiling light coming down through the translucent dust cover on the vertically-facing eyepiece. If you got lost among all of those reflections, no worries–see the ray-tracing diagram for a Gregory Maksutov here.

Outside, ready to go. Note the purplish color of the meniscus, caused by the magnesium flouride anti-reflection coatings. On refractors, the best fully multi-coated lenses look like dark-green holes, they just swallow incoming light like you wouldn’t believe. From what I’ve seen and read, catadioptric scopes like Maks tend to have correctors that are almost invisible if they have top-of-the-line coatings. This less well coated corrector shows some reflections, but in truth the difference is slight, just a few percent of the total incoming light. To see some photos of the correctors on other 90mm Maks, including a Questar, see Ed Ting’s 3-way comparo here.

I was all set up to take some pictures of the male hummingbird who sits in the top of our neighbor’s tree, but the little sod must be psychic. Every time I got the camera settings right and the camera to the eyepiece, he’d fly away. My time was limited and eventually I had to give up and go do other things. You can see some birding photos I got through my old Orion 90mm Mak, including what might be the same hummingbird, here.

I knew from the online UPS package tracker that the scope was coming today. For the past week, Weather Underground was predicting clear skies tonight. But sure enough, the New Scope Curse struck, and about sunset the sky went from a few scattered clouds to completely socked in. So the only views I got through the scope today were of a distant treetop to get the finder aligned, and a few seconds’ observation of that rotten hummingbird. Everything looked good and I didn’t see any obvious problems, but starlight will be the real test, as it is for any scope. Not tonight, unfortunately!

In lieu of a first-light report, here’s what I learned from the unboxing and my few minutes outside with the scope:


  • The scope is real purty. Fit and finish are very nice.
  • Mechanics seem good. Focusing is smooth with no detectable backlash, at least at the low magnifications I was using during the day. Stay tuned.
  • Given my extremely limited time out with the scope, the optics seem fine. At 50x with the 25mm Plossl, I was counting scales on a tiny pollen cone in the top of a tall pine tree half a block away. I had no problem focusing directly to a crisp image, without having to flop around on either side of focus until I got it right–again, under the forgiving, low-mag conditions I was using it in today. No false color detected, but I haven’t really put it to the test yet.
  • I haven’t used the supplied mount yet, but it gives a reassuring impression of solidity and has some nice touches I didn’t expect, like the built-in bubble level, included L-bar adapter, and Velcro strips for hanging the hand controller from the side arm.


  • I’m disappointed that the diagonal has a prism rather than a mirror. Mirrors tend to be much sharper, especially at the high magnifications Maks are capable of delivering. Now, most Mak spotting scopes come with 45-degree prism diagonals so this one isn’t behind the curve, it just seems weird that essentially all Mak-makers (Questar excepted, obviously) hobble their scopes as shipped with inferior diagonals.
  • I knew this coming in, but the supplied finder is tiny, and uncomfortable to use since I have to crouch behind it. Unfortunately I don’t have the 6×30 RACI anymore that I used to use with my little Maks. For review purposes I will use the supplied finder, but when it’s just me using the scope for pleasure I am either going to have to move the 9×50 over from one of my bigger scopes or buy another optical finderscope (or, just maybe, see if I can get along with dead-reckoning using a spare red-dot finder I have laying around). Also, the finder bracket is not one of the convenient two-bolts-and-a-spring models but an old-fashioned six-screw job, which means that getting the finder aligned takes about 5 times as long as I’m used to.
  • The choice of eyepieces is odd, because each one is a factor of two away from another one. One of the most common astronomical accessories is a 2x Barlow lens, which effectively halves the focal length of any eyepiece. Eyepieces are often sold in staggered pairs to take advantage of this. For example, my first scope came with 25mm and 10mm Plossls, which when Barlowed gave me four focal lengths to choose from: 25mm, 12.5mm, 10mm, and 5mm. If they were similarly staggered, the three eyepieces included with this scope could have yielded six magnifications when Barlowed. Instead, they give just four: 25mm, 12.5mm (both natively and with the 25mm Barlowed), 6.3mm (both natively and with the 12.5mm Barlowed), and 3.2mm. So the 12.5mm eyepiece is superfluous if you have a Barlow. On the other hand, this bundle is clearly aiming for everything-a-beginner-needs-in-one-box completeness, and if you don’t have a Barlow yet, having three eyepieces is very convenient. Most other Maks come with just one (although some C90 packages come with two); advantage SkyWatcher.
  • The optics are coated rather than multi-coated or fully multi-coated. I haven’t had a chance to see if this makes a detectable difference at the eyepiece. It only strikes me as odd because I have seen so many affordable Chinese-made scopes that are multi-coated that I had started to assume that was the new baseline.

I see that I went on at much greater length about the nots than the hots. Don’t read too much into that, it’s mostly whinging about accessories which are just as good as or better than those shipped with most other 90mm Maks. The only criticism that applies to the scope itself has to do with a level of lens coating that may not make much difference in actual practice. Remember that these are all first impressions; I have not yet had the scope out under the stars. Until I have done that and reported back, take this post for what it is: a list of parts.