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- COUNTING SUNSPOTS WITH A $10 OPTICAL TUBE ASSEMBLY
- Hubble Optics 14 inch Dobsonian - Part 2: The SiTech GoTo system
- iStar Optical’s Phantom FCL 140-6.5 review
- Who’s Afraid of a Phantom: Istar Phantom 140mm F/6.5, that is?
- SHARPSTAR 94EDPH APOCHROMATIC REFRACTOR
- My Losmandy G11T review
- FIELD TEST: THE NOH CT-20 ALT-AZ MOUNT
- SkyTee-2 Alt/Az Mount Review
- SharpStar Askar ACL200 200-mm f/4 astrographic telephoto lens
- A review of the Unistellar EVscope
- Astrotrac 360 tracking platform – first impression
- FIELD TEST: CARL ZEISS APOCHROMATIC & SHARPEST (CZAS) BINOVIEWER
- Omegon 32mm 70º SWA eyepiece review
- Review of iPolar hardware and software for polar alignment
CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.
Cn Report: Meade 12" LightBridge Deluxe
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Meade 12” LightBridge
A mass produced truss Dobsonian telescope
Truss dobs are cool.
Ok, I’m a scope freak. I said it. All of you out there who already knew that, raise your hand. Hmmm. All right, you can put em down now. Looks like I didn’t surprise anybody.
I love telescopes. That said, truss dobs have to be one of my favorite designs. A Newtonian / Dobsonian gives you (by far) the most bang for your buck in this hobby. If you want a big scope, you want a dob. (and lets be honest – if you REALLY want to go deep, who doesn’t want as much of a scope as they can get?) With the influx of Asian dobs over the last few years, quality has risen while costs have fallen. Oh, sure, the imports aren’t without their flaws, but hey – they’re worlds above what was available just a few years ago. My first serious telescope came from Orion, and if you’ve read any of my other dob reviews, you’re probably familiar with it, so I’ll spare you the gruesome details and just say what’s available now is vastly superior.
The typical Asian dob is a heck of a deal, especially when you are looking at a 10” or 12” telescope. Where else can you get twelve inches of aperture for under a grand? What’s more, 12” of aperture that’s NOT a project scope? At least for the most part. Now that’s a no brainer.
There’s only one thing lacking. Portability.
Those 12” tubes are rather large, and transportation can be an issue – particularly if you have a small car, getting the scope to a dark site can be problematic.
Enter the truss design. It’s been the staple of the high end dob world for decades. Obsession telescopes practically ushered in the new era 20 some years ago. The truss Dobsonian allows you to have your cake and eat it too. You can pack a large telescope into a very small volume, making transport far easier. There are some trade offs – a solid tube dob tends to hold collimation (optical alignment) a bit better, and it’s also less prone to thermal issues from nearby observers. Since the tube is solid, odds are the mirror is better protected from things that go bump (or drop) in the night, and the solid tube also helps to shield the primary from dew and frost a bit better.
But trusses are beautiful. Yeah, I’m a scope geek.
Until now, if you wanted a truss telescope, your options were fairly limited. You could go high end and pay top dollar, or you could build one yourself.
Enter the worlds first mass produced truss scope.
I’ve really got to hand it to Meade on this one – let me say that up front. The market has been crying out for this for years. They saw a niche, and filled it, and for that I applaud them.
Now let’s see how well they did.
The LightBridge is made by GSO for Meade and currently comes in three different sizes and two different flavors. You have a choice between an 8”, 10” or 12”, and you can get the deluxe or regular flavor. The deluxe offers an improved finder, a better included eyepiece and a tension adjustable roller bearing for the AZ axis.
I received a 12” LightBridge Deluxe for review. Although sent by Astronomics, it was drop shipped direct from Meade to my home in Michigan’s Thumb.
The LightBridge arrived in two large boxes – the base (disassembled) in one, while the truss poles, mirror box, mirror, UTA and additional accessories (finder, 2” Meade 26mm QX eyepiece) in the other.
It was in shipping that the first glitch showed up.
The LightBridge comes with an extremely light weight mirror cover. In more expensive truss scopes, there is a mirror cover that rides on the top of the mirror box and shields the mirror from dust and potential damage. The Lightbridge uses a very inexpensive piece of plastic that rests directly on the mirror and its retaining bolts. The problem arose in that this cover was not properly secured for shipping, and the mirror box is shipped sideways in the container. Predictably, the mirror cover came loose, bounced around in transit, and managed to damage the coatings in several locations. In one respect, I was lucky – other users had reported far worse damage. In this case, the issue was confined to a couple of locations around the edge of the mirror.
Damage like this is ironic, in that it would have been so easily prevented. All it would have taken would have been a couple pieces of tape or Velcro on the mirror and cover to ensure that it didn’t slip in shipping.
They did adjust to this issue rather quickly, and current LightBridges are shipping with the mirror cover affixed for shipment through the use of small portions of Velcro.
Assembly was straightforward. The base is the typical Asian Dobsonian base – glueboard with a laminate over the top. I’ve probably assembled a half a dozen of these over the last couple of years. I put it together one night while an episode of law and order played in the background. It was assembled before Jack McCoy had been dealt the “twist” in the case – in other words, just under 35 minutes. Assembly requires using the supplied allen wrench. After the base is assembled, no further tools are required. Kudo’s to Meade for providing a no tools assembly for the field! Unfortunately, collimation isn’t quite as easy.
The scope itself took even less time. All that was required was to plop the mirror box into the rocker, then affix the 6 trusses (connected to form three sets), and attach the Upper Truss Assembly (UTA). Attach the finder, and we’re in business.
Stepping back to look at it, one thing strikes you immediately. It’s a pretty telescope.
The aluminum bearings ride on felt and the truss poles are a nice sliver that contrasts well with the overall white of the telescope.
The AZ tension is adjustable – thank goodness. I’ve used the roller bearing design before, and to be honest I’ve not really been fond of it. I could never seem to get the correct tension. Either it spun around so fast I got dizzy, or it was so tight, you could feel the individual rollers grab and roll. The tension adjustment allows you to directly dial in the tension you like. And a good thing too. In the ideal dob, motions are identical on both axis. On the lazy susans, I’ve found that the base spins like a top. This allows you to counter that.
The Alt-tension isn’t adjustable – but it had just about the right amount of stiction. While I had balance problems with some of my heavier eyepieces and accessories, most caused no issue. (For those who have a balance problem, DBA offers a magnetic counterweight kit for these types of scopes that works like a charm.)
Frankly, I was a little underwhelmed by the overall stability of the base. The rap test showed vibrations at moderate powers to settle down in around 5-8 seconds. Initial vibration is obvious even when not looking through the scope – meaning you can give it a light rap and watch it shimmy and shake without even looking through the eyepiece. In retrospect, I think there are several issues at play here.
The feet of the base are a hard rubber like material, that I suspect is contributing to the lack of stability. I’d replace those with some small wooden blocks. If that didn’t solve the issue, I’d look at adding a side board or two to stiffen the sides a bit. I noted a similar issue with the 12” GSO I saw last year. While this amount of support is adequate for an 8” or even a 10”, it leaves something to be desired with larger telescopes. Still, I found the scope fairly useable, although this was part of the reason that I found high powers a bit challenging.
Much has been said about the motions of this scope. Most folks seemed to think they are quite nice, but I’d have to qualify that a bit. While the motions may be very nice for a mass produced scope, I found them simply not in the same league as many of the premiums – in particular, StarSplitter, Obsession, Teeter, and StarBuckets. In fact, initially, they were extraordinarily stiff, and the first time I removed the scope from the rocker box, I found out why.
As you can see, the tolerances were just a little too tight. The lip of the alt bearing cut into the rocker box, making the initial motions quite stiff – at least until it cut the channel you see here. Once it had “broken in” (and after I cleaned the bearing to ensure a smooth surface) I found the motions acceptable for tracking up to 200x or so. Beyond that, the stiffness of the bearing coupled with the undersized rocker box and general lack of stability made observing a somewhat less than fun experience, although the stiffness did ensure that I had few problems with balance. The only eyepieces that really threw things seriously out of whack were my 40mm TeleVue Widefield (an oldie but a goodie) and the 28mm UWAN (a real monster).
Frankly, I wish that GSO and Synta would abandon their use of undersized bearings and non-traditional materials, and simply go with what’s been tried and true for 20+ years. A good rule of thumb to follow for someone looking at bearings would be to keep the diameter of the bearing to 1 or 1.5 times the aperture. While the felt bearings work (better than I expected to be frank), I have some minor concerns about their long term durability (felt compresses), and the lack of adjustment (although rumor has it that an Alt tension device is in the works).
The truss is a rather unconventional 6 pole design. It worked well, and I found there to be minimal issues with flexure. I did note that collimation did shift slightly from horizon to zenith (but I suspect this more due to the cell than issues with truss rigidity). However, the six pole design makes life somewhat difficult when trying to fashion a shroud. I should note that although Meade didn’t ship a shroud with mine, the LightBridges they were showing at NEAF all did have shrouds. A sign of things to come? I don’t know. In any case, a shroud is a must have for many observers. Not only do they block stray light, and minimize the chances of anything getting dropped on the mirror, they also tend to act as dew shields - perhaps their most important function here in the Midwest. Unfortunately, the six pole design means that unless some special measures are taken, the shroud will most likely sag into the light path and effectively reduce your aperture. If the shroud is designed correctly (most likely with stiffening hoops around the middle) this becomes a non-issue. While the Meade shrouds on display had no stiffeners, AstroZap manufactures one that does, and I highly recommend either purchasing or fashioning one of your own.
I’d also recommend looking into acquiring a light shield for the end of the upper truss assembly opposite the focuser. I found the focuser to be placed a little far forward and noticed some stray light in the eyepiece a couple of times that looked to have come off the front. AstroZap sells one of those as well.
Although a single speed, the stock crayford focuser is quite nice. Focusers have come a long way in the past few years, I can remember when a focuser like this was considered an upgrade for many telescopes. I did find focus travel to be somewhat limited – while with most eyepieces I had no focus issues, there were a couple of different eyepieces that I needed an extension tube. While the QX worked ok for me, I have heard that others have had to pull it out of the drawtube a bit to bring it to focus.
If you’re looking to upgrade to a dual speed, DBA Astronomy Products offers an aftermarket drop in replacement. Basically, it’s the same focuser, but has a 10 to 1 reduction knob. While it’s not a FeatherTouch, I found it to do the job very well. Both focusers are rotateable, a feature you may want to take advantage of. If you look at the photo, you’ll see that I’ve installed the focuser “upside down”. This allows me to keep my thumb on the fine focus while guiding the telescope – kind of a neat trick that I’m not really sure where I picked up.
The mirror cell is apparently the standard GSO cell, and there are some issues with it. First off, while Meade made sure that we could assemble the dob in the field without tools, for some odd reason the scope requires BOTH a flathead (see photo below) and a Phillips (see photo above) screw driver to collimate it. The primary collimation screws are recessed to far too comfortably grab them with your fingers, so you typically have to resort to using the flathead screw driver. This dob should really have longer collimation bolts with thumb knobs for both the primary and secondary. I know that ScopeStuff was looking to sell a replacement kit at one time, but as of this writing I haven’t seen it appear on their web site.
And speaking of collimation - one of our forum members reminded me of something I forgot to mention in an earlier incarnation of this article. While the collimation bolts for the primary don't extend far enough to get a grip on with your fingers, they do extend beyond the lip of the cell - just enough so when you set the ota on it's base (like you would when moving the scope), the full weight of the scope rests on those collimation bolts. As you might think, this can adversely effect collimation. To avoid this, you may want to lay the scope on it's side when it's not on the base, collimate when setup for observing, or investigate some alternate solutions.
But those weren't the only problems with the cell.
I’ve owned truss dobs for many years now, and collimation is typically a 5 minute process when everything works well. The Meade took me about an hour to get acceptable collimation the first time, and while it got easier with practice, I never did get down to the 5 minute mark. A close examination of the workings revealed why. Ultimately I discovered that the springs Meade uses simply weren’t strong enough to correctly support the weight of the 12” mirror. Since it wasn’t properly supported, it didn’t move as freely in the cell as it should have, collimation was a real pain, and exacting collimation was nearly impossible. Frankly, I’m not sure that I ever got to see the best images this mirror was capable of producing.
New bolts and springs would be an improvement.
As you can see, they do include a fan - a good thing. Note the data for cool down time of a 12" mirror over an 8 degree temperature delta in the graph below. As you can see, with a fan, the cooldown time was about 20 minutes and without any active cooling around 60. In northern climes where the temperature can fall nearly all night long at times, some form of active cooling is absolutly critical.
The included RDF is basically the same as offered under several different brands (WO, Burgess, etc…) and for the most part it makes a pretty nice finder. It’s been around for a number of years – it was initially designed to be a gun sight, and one hold over from those days is that I find it to be a little too bright for my comfort from a dark site – as all the rest. It has several levels of brightness adjustment, and 4 different sights to choose from. The neatest thing about it was this was the first time I’ve seen it offered on a stalk that fits into the standard syntax finder base. The finder attaches to a weaver style base at the top of the stalk. Although it seems like a small thing, the stalk itself is a pretty cool item, and one that I wish meade would make available separately. I’d suspect that there are folks who would be only to glad to pony up $10 or so for the ability to swap out an optical finder for a reflex unit at the drop of a hat.
Meade also includes one of their 26mm QX eyepieces with the deluxe version. While nice, performance isn’t stellar, and eclipsed by their series 5000 line up. I suspect this keeps costs low while offering an upgrade path to the user.
In the Field
A 12” f5 is a good choice for a deep sky scope. 12” is big enough for some serious light gathering power, while the f5 focal ratio is slow enough that most users won’t be overly bothered by coma. Additionally, it’s just about the perfect height for most observers to use while seated.
As per portability, this is where the truss design comes into it’s own and the no tools assembly is very nice. I'd also note that the hardware is captive, so you won't loose those black handles in the night. Note the upper truss assembly in guided together by the small lip on the cage, (as shown above) and for the lower assembly, the truss poles fit into posts which tighten and hold it in position. Altogether this I consider this a pretty innovative design.
Now if we could only get those primary and secondary collimation screws changed out for thumb bolts, and stiffer springs installed, I'd be a very happy man.
Back on portability tho, while I’m not convinced that most folks really have a need for a truss 8 or 10 inch telescope, but there are some definite advantages to a 12” truss. While the mirror box (it seems strange to be calling a round portion a box) is a tad on the long side, it’s far shorter than trying to shoehorn a full size 12” OTA into your trunk. The poles are probably the longest items, but those aren’t long enough to cause one to worry about space issues either.
Under moderately good skies a 12” is capable of showing you multitudes of deep sky objects, and detail in tons. Globulars bust apart, Planetaries reveal their central stars and details in their structures. Galaxies reveal their spiral arms, and reflection nebula go from faint fuzzies in to splendid objects – just like the pictures on the box – oh, wait a minute - wrong product…. Seriously though, make no mistake this is some serious aperture, and will keep the owner happy for many many clear nights.
The 26mm QX is a decent eyepiece, and I suspect most beginning to intermediate observers will be quite pleased with it – at least until they discover the world of Naglers, Panoptics, Pentax, and the like. I found the view to be acceptable for approximately 80% of the field of view – beyond that I had some minor issues with astigmatism.
GSO has been turning out some very nice optics lately, and even though exacting collimation was something of a daunting task, I could tell that this mirror was a pretty decent example. I saw no gross errors of figure, and it took magnification well, right up to what I considered the limits of the system as a whole – around 200 to 250x.
Of the several I’ve seen, the most common issues have usually been related to minor amounts of under correction and a rough optical figure – not things which are going to be major problems in a scope like this. For most applications this scope will perform very nicely (as long as you can get collimation sorted out). However, if you’re thinking about this as a planetary scope I’d recommend you consider upgrading the cell and taking a long hard look at a platform. Most people won’t be concerned about that tho – I figure you buy a big dob to look at DSO’s, not planets. (Yeah – Vic, I know, I know, but hey….)
Summary and Final Thoughts
I reviewed the 12” deluxe version, but I suspect that I could have been very happy with the regular edition – I’d simply have replaced the lazy susan bearing with Teflon, and kept the same dot sight. I already have a plethora of decent eyepieces, but not everybody is in the same boat.
Twelve inches is about the smallest size I can typically see as practical in a truss telescope (yeah, I know, I had one smaller and as nice as it was I wound up selling it). Basically, below 12 inches, most people just aren’t going to need the extreme portability, and if they are, they are probably better served building a suitcase dob, or purchasing one of the premium setups out there. While there are several reasons I’d recommend going with a solid tube in the lower sizes, in this case I think the one that stands out the most is that you don’t have to worry as much about collimation.
So am I panning this scope or what?
It may seem that way, but I’m really not. Yeah, there are some warts, and a few real head slappers (come on Meade – no tools assembly, but then Slotted AND Phillips for collimation??), but the bottom line is that it’s the FIRST mass produced truss dob. Period. No one has ever done this before, and you have to hand it to them for innovating. What’s more, rumor has it that there’s a 16” version in the pipeline (PLEASE beef up the base) and I predict that if Meade (or GSO) can bring that one in at a similar price point it will sell like hotcakes. Heck, for that matter, I expect these to sell quite well as they are. This is a lot of telescope for the money.
Meade is to be commended for bringing a truss dobsonian to the mass market. Although the LightBridge is not without it’s warts, most of those are fairly easily remedied by anyone willing to scour the aftermarket or indulge some minor ATM leanings and frankly, nearly any dob is going to need something – counterweight kit, fan install, etc… While it’s not a competitor to the premium scopes, and at 1/3 the cost of a premium truss nor is it really intended to be such, it’s got a lot of things to recommend it – not the least of which is it’s low cost, large aperture, high portability and its plain and simple cool factor.
Meade, you've done good. Now take it to the next level.
- Philler and Zachrey like this