Archive for the ‘Cheap Scope Reviews’ Category

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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.

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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 12.mm 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.

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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:

HOTS:

  • 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.

NOTS:

  • 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.

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Cheap Scope Review: the Celestron FirstScope

October 11, 2011

Update: This post seems to get a lot of traffic, especially around the holidays. If you’re looking for good gifts for amateur astronomers, including telescopes and binoculars that won’t break the bank, you may also be interested in my astronomical wish list for beginning stargazers.

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My fascination with small, cheap scopes is probably obvious by now. Don’t get me wrong, I love my 10″ reflector, and if someone said I could only have one scope for the rest of my life, that would be it. But there is still something about wee little scopes that tugs at my heartstrings. I want to try out every one I come across, and see what it can show me. Partly this is an internal, personal fascination with small telescopes, probably akin to the fascination that some people have for very small trains or very small dogs. But it also has a social component. I do a fair amount of sidewalk astronomy, showing the moon and various other things to passersby, and I like to be able to recommend inexpensive telescopes to people. So I’ve been on a quest not only to find the perfect small scope for myself (a quest that is complete…for now), but also the perfect small scope to recommend to other people.

You might think those would be the same thing, but they’re not. If there is a posh end of the little tiny scope market, the SV50 is it. It’s a nice instrument–very sharp optics, within in the limitations of a 50mm f/4 optical train, a smooth focuser, and a rugged build. All this comes at a price. It was a price I was happy to pay, to get a scope that fit my peculiar requirements (being able to be stuffed into the bottom third of my backpack for long airplane flights to dark skies in other hemispheres), but for most people the SV50 is build quality overkill and optical underkill. For the same $150, you can get a 3 or even 4 inch scope on a solid mount, and those larger scopes are still nice enough to be all the scope that some people will ever need.

A few years ago the conventional wisdom–which can still be found in quite a few places out in the wilds of teh intarwebz–was that first-time scope buyers should avoid anything under $300. Then the recommended cutoff fell to $200. Then some manufacturers started building very well received scopes for $150, like the Orion StarBlast 4.5 (which is now up to $200, although you can get the tube alone for $150).

It’s not that there weren’t scopes available for less. Depending on your tolerance for plastic and frustration, the low-end department store scopes grade into toys that go all the way down to about a buck. But these were not in any sense “good” telescopes, and between bad optics and shaky mounts, standard department store telescopes have probably driven thousands of potential stargazers away from one of the most rewarding hobbies. For a long time, the minimum buy-in for a new telescope that actually worked as advertised was between $100 and $150.

That changed, bigtime, during 2009, the International Year of Astronomy. First there was the GalileoScope, which originally sold for $15 but nevertheless managed to attract plenty of good reviews and a strong following online. Galileoscopes are still available, although now that IYA2009 is over, the economy of scale isn’t working as well and the price has gone up to $50.

In the same year, Celestron released the FirstScope, a 3-inch reflecting telescope on a one-armed tabletop mount. The FirstScope was an official product of IYA2009 and was heavily promoted and ended up in a lot of places, including electronics stores and even department stores. It originally sold for $50, but the price has periodically been lower. As of this writing they are $45 with free shipping, but I have seen them as low as $36 online and people report finding them in Fry’s and other electronics stores for as little as $25. The box includes the assembled scope, two eyepieces, and a single sheet of instructions. As far as I know, it’s the most inexpensive, reasonably capable, complete telescope ever brought to the market. So naturally I was curious about it, and the combination of a temporary sale and an Amazon gift card put one in my hands for a while last year.

Let’s start with first impressions. This is a sharp-looking scope, right out of the box. It includes dust covers for the end of the tube and the focuser, and the two eyepieces come with plastic caps, and in general it has the same fit and finish of other mass-produced scopes. The tube is printed in spiraling script with the names of famous astronomers from the past, which I think is not only commemorative but also educational, in that people are supposed to read the tube, see names they don’t recognize, and go learn about them. The tension on the altitude axis is easily adjustable with a big knob that turns against a Teflon bearing surface. The mount turns easily on its base, and the base has three big rubber feet widely spaced for stability. No finder is included, but there are a couple of pre-drilled holes with screws for mounting one.

As usual with “tabletop” scopes, observing with the FirstScope may require some ingenuity if you don’t have an actual table handy. It’s small enough and the useful magnifications are low enough–more on this in a second–that you could just hold it by hand or cradle it in your lap. I used to prop mine on the trunk of the car, back when I still had a car with a trunk. The base is a big plus here–the three rubber feet give solid footing with no rocking, even on uneven surfaces, and the mount is small enough and strong enough that vibration isn’t a factor. The altitude and azimuth motions are also very smooth, so once you get something in the eyepiece, it’s generally pretty easy to keep track of it.

So far, so good; most cheap scopes are so wobbly and shaky that finding targets and then tracking them is an exercise in almost terminal frustration. Mechanically, the FirstScope is as smooth, steady, and convenient as any scope I’ve ever used, and that’s an unbelievable achievement in a bargain-basement scope.

Back to the ease of tracking things at the eyepiece: there’s the rub. How do you get the scope pointed at things, so that you can see them in the eyepiece? With most scopes, you point the tube in the rough direction of your target, look in the finder scope, center the target, and then go to the eyepiece. Without a finder, you’re down a step: all you can do is point the scope in roughly the right direction and hope for the best when you look in the eyepiece. With the moon this is almost foolproof; with anything else it can be surprisingly tricky. Admittedly, with the low power eyepiece the scope has a huge field of view, which makes acquiring objects somewhat easier, but I still found that observing anything other than the moon usually involved at least a little faffing about.

Once on target, how are the views? Here’s where you have to steel yourself to some unavoidable facts of optics and economics. First the optics: it’s dead easy to make a mirror whose surface is a segment of a sphere, all you have to do is rub two flat round pieces of glass together with abrasive in between and that’s the shape that emerges naturally. The problem is that a spherical surface doesn’t bring all of the parallel rays of light that fall on it to the same focal point. The shape that does is a parabola, which is not that hard to generate but still takes some extra figuring from the basic spherical shape.

Now the economics come in: for Celestron to produce FirstScopes at their target price point and still stay in business, they could not afford to parabolize the primary mirrors. That wouldn’t be a big deal if the focal ratio were longer. When the cone of light from the primary mirror to the focal plane is long and skinny, the rays converge well enough that past a certain point spherical mirrors perform just as well as parabolic mirrors. The Orion XT4.5 has a spherical mirror and most reviewers have been very complimentary about how sharp the views are. But the XT4.5 operates at f/8, meaning the light cone is eight times as long as wide (or to put it in more technical terms, the focal length is eight times the diameter of primary mirror). The FirstScope operates at f/4, which means a pretty steep light cone. Even parabolic f/4 systems are hard on eyepieces: it’s difficult to gather up that steeply angled light and turn it into a pleasing image. Without some kind of complex and expensive corrective lens, objects in the center of the field will be sharp but those toward the edge of the field take on interesting, compressed shapes, sort of like a photo taken with a fish-eye lens. With an f/4 spherical mirror, the visible aberrations are worse, and even objects in the center of the field may not be truly sharp.

This is in fact exactly what I found. I could see plenty of craters on the moon, but the views were fuzzy rather than razor-sharp. Jupiter would go from being an elongate smear on one side of focus to an elongate smear on the other side, but in between it never really settled down into a nice circle. The best I could get was a modestly flaring egg shape, although the moons on either side were easy to see. Stars went from being vertically elongated dashes to horizontally elongated ones without ever becoming nice round little points of light. And that was in the center of the field. Toward the edge, the stars became commas, parentheses, and seagulls.

Not only were the eyepiece views pretty underwhelming in terms of quality, they were also small. Economics again: a decent, well-corrected eyepiece with a comfortable apparent field, like a generic Plossl, costs about as much as the entire FirstScope package. The included eyepieces are a 20mm Huygenian yielding 15x and a 4mm Ramsden giving 75x. The Huygenian has a tiny field of view, like looking through a soda straw, but the views are at the sharp end of what this scope is capable of. The 4mm Ramsden has a wider apparent field, not as good as a Plossl but not entirely claustrophobic, but unfortunately 75x is really pushing what this scope can do. Orion packages their almost identical FunScope with 20mm and 10mm eyepieces giving 15x and 30x, and I think those are much more reasonable magnifications for this type of scope. Happily, the focuser accepts standard 1.25″ eyepieces so if you can use other eyepieces, and frankly almost any other eyepieces are going to be better than what comes in the box.

Regardless of what eyepiece you use, focus gets critical at fast focal ratios, because the steep angle of the incoming light means that the focal plane is extremely shallow. With a long light cone, the eyepiece travels through the comparatively long region where the light rays are almost imperceptibly out of line on either side of perfect focus, which means that you can adjust focus very precisely with reasonably big turns to the focuser wheels. With a steep light cone, even minute turns of the focuser can throw you from out of focus on one side to out of focus on the other. Sometimes the distance between visibly out of focus in both directions is less than the spacing between the teeth on a rack-and-pinion focuser, so the perceptible ratcheting of the focuser can throw you past focus. I also found this to be the case; the focuser had an almost imperceptible amount of slack which was greater in one direction than the other, so I had to deliberately overshoot the focus in the “bad” direction and then try to sneak up on it from the “good” one. If I went even a hair too far, I couldn’t simply reverse into focus, but had to go way past in the wrong direction so I could start sneaking up again.

Needless to say, this kind of monkeying around gets old pretty fast. It might have been worth it for reasonably sharp views, but not for a fuzzy moon or egg-shaped planets. I used my FirstScope off and on, halfheartedly, for a few months, and then passed it on to someone who was happy to get it.

PROS

  • Extremely light and portable
  • Solid mount with good motions
  • Good fit-n-finish, comparable to what you’d get on much more expensive telescopes
  • Visually attractive, commemoration of prominent historical astronomers is a nice touch
  • Usable right out of the box
  • Dirt cheap

CONS

  • Almost zero instructions (in the box; more are available online, but for what telescope is that not true?)
  • No included finder
  • Included eyepieces are usable, but barely
  • No provision for primary mirror collimation
  • Very limited magnification potential
  • Underwhelming image quality

It may seem mean to bring up these cons on a complete telescope that costs about as much as a cheap eyepiece. After all, fixing any one of them–adding a finder, or better eyepieces, or an adjustable mirror cell, or parabolizing the mirror–would drive up the cost, and then this scope wouldn’t be filling the same niche anymore. In fact, the telescope ecosystem includes a whole array of small reflectors that improve on the FirstScope in some way, so you can see what the upgrades cost. For $60, the Orion FunScope is virtually a clone of the FirstScope, but it adds a red dot finder, better eyepieces, and a socket in the base of the mount so the whole thing can be put up on a tripod. For $100, the SkyScanner 100 adds (in addition to the RDF, better eyepieces, and base socket) a parabolic mirror with twice the light-gathering area (but still no collimation), or the SpaceProbe 3 Alt-az adds (with RDF and better eyepieces) a full-size tripod, a collimatable primary mirror cell, and a longer focal length for more magnification and sharper images. And things go on up from there.

Still, somebody has to be at the bottom of the price ladder. Considering that it costs almost nothing, the FirstScope is actually a remarkable success. It is certainly not useless. It will show a lot of stuff, and I think it is much more likely to pull first-time telescope users farther into astronomy instead of driving them away like most department-store scopes–although the pull may soon be to a bigger or better scope.

Should you get one? Although I’m sympathetic to the design philosophy of the FirstScope, I’m going to recommend against. Here’s the deal: the Orion FunScope currently costs a full third more, but that full third is still only $15. Most people who can afford $45 for a telescope can afford $60, and the addition of the red dot finder alone (which sells for about $36 as a stand-alone item!) is worth the extra layout, in terms of the convenience it will bring to using the scope.

But honestly, I wouldn’t stop there. The FirstScope and FunScope are fine for getting your feet wet, or for having a well built (if optically wanting) small scope to play with, but I have serious doubts about how long they will hold most people’s attention. In my opinion, the next rung up ($100) is where the “keepers” start. What I mean by that is that the SkyScanner 100 and SpaceProbe 3 have good enough optics to be useful for a lifetime, and recently received very favorable reviews in Sky & Telescope. Even if you already have or someday move on to bigger scopes, they’d be worth keeping around as quick-look, grab-n-go, and travel scopes. Bottom line, if I got marooned on a desert island with a FirstScope, I’d grudgingly make the best of it, but if I got marooned with a SpaceProbe 3 I could probably keep myself happily occupied for the duration.

So what’s the final word? I think most people, even casual observers or kids, will be better served with a slightly more capable–but inevitably somewhat more expensive–scope. Nevertheless, I am glad that the FirstScope exists. It serves an extremely useful purpose: providing a rock-bottom entry-level scope that actually works.