Image of the day

Captured by
Silvia Oschatz

NGC 6992 "bone hand"

My Account

New to Astromart?

Register an account...

Need Help?

Meade LS 8 ACF Review

Posted by John Kramer   09/04/2010 01:29AM

Meade LS 8 ACF Review
Meade LS 8 ACF - First Impressions

As some of you may already be aware, I posted a 3-part review of my ETX-LS 6 ACF some time ago. I thoroughly enjoyed that scope, the optics, auto-alignment and GOTO capabilities were all in a convenient package that was a good balance of performance and portability. I honestly had grown fond of a 6 inch optic over the last year and a half. Since my apartment had an extremely limited view of the night sky, that size telescope was a great fit to my observing style; a mix of very limited quick peeks and visits to a nearby suburban observing site only when my schedule permitted. It was because of those reasons that my 6 inch ETX-LS ACF and Orion XT6i were used almost exclusively by me for the last year and a half. I preferred them over the larger 8 inch SCT I also own, primarily because of their portability, performance, and GOTO capabilities. In a nutshell, the optical gain of an 8 inch wasn't enough to outweigh the electronics of the other scopes. I had viewed more objects and had enjoyed my time under the stars more in the last year and a half with my smaller scopes than I had ever done in 15 years with my non-computerized 8 inch SCT.

Recently it became clear that my living arranges would finally be changing and offering me the opportunity to have a yard with a 360 degree unobstructed view of the night sky. With that revelation, portability became less of a concern and I found myself actually longing for the extra light grasp of my 8" SCT, but cringed with the thoughts again of spending more time searching for targets than actually viewing them. Then in April, Meade released the LS 8, and my problems were solved. So it was with a degree of sadness that I released my ETX-LS 6 ACF to make room for its big brother, the LS 8 ACF. I could have the best of both worlds I thought, the light grasp and additional resolving power of an 8 inch optic and the GOTO electronics I had grown so found of from the ETX-LS. But would the LS 8 ACF provide to me the same fun experience as I had with the smaller ETX-LS 6? Would the optics be as good? How about the GPS, did Meade solve those intermittent problems? Well the answers to those questions and more are below in my review of the Meade LS 8 ACF.

So what is a LS 8 ACF anyway?

The Meade LS 8 ACF is the newest, and no doubt will be the largest model with this current mount in the LS (LightSwitch) series. The ETX-LS series were originally released in 2009, and then in 2010 Meade re-introduced the updated series as simply the LS. I'm not sure the reasoning by Meade on this, but they probably wanted to emphasis the LightSwitch technology and have it "evolve" from the long line of ETX models. Originally released as a 6 inch Standard SCT model and then a 6 inch ACF model, the LS series now includes 8 inch versions of SCT and ACF. Mine has the optional ACF (Advance Coma Free) optics with UHTC coatings (Ultra High Transmission Coatings), and now after almost a year under the stars with an ACF equipped telescope, I can honestly say that I actually do see the visual appeal to this design, to me stars appear smaller and more pinpoint. I really love that, so much so that I can say without a doubt that I'll never own a standard SCT again. ACF was designed by Meade to enhance the scopes optical performance by reducing coma and thus improving the sharpness of the star images. I personally notice the difference. Because of the ACF optics, it is said to perform optically on par with more expensive Ritchey-Chretien or RC optical designs. On the occasions I compared the LS 8 to my older, Schmidt-Cassegrain Celestron Ultima 8, the stars certainly seemed more pinpoint to me in the LS 8, and less "bloated". The LS 8 ACF also has 78% more light grasp than a 6 inch scope. The increase of aperture is apparent vs. a 6 inch, but not a "wow" effect in my opinion.

The most important selling point of the LS however is the LightSwitch Technology. Once the scope is turned it, it permits the scope to automatically level itself and find north (Meade calls this Level/North Technology), then with the use of its internal EclipseCCD camera and on board GPS, alight itself to the night sky without any user intervention. The steps are simple, flip the switch. Once the scope is turned on, you're greeted by the "Astronomer Inside". The "Astronomer Inside" gives you a brief introduction to the LS 8, and informs you of each and every step of the way during the alignment process. First up is raising the OTA horizontal, and acquiring the GPS, so that the telescope has its location and time. From its acquisition of position and time, it can then find level, find north, and then it proceeds to do the two star alignment. It performs this alignment by pointing the telescope in the general vicinity of the first alignment star, and takes an exposure of the sky with the EclipseCCD camera I mentioned earlier. Using software and image processing, it can then determine how far off the alignment star is by comparing the image to where the telescope is actually pointing. It then makes the necessary physical corrections, and repeats imaging until the alignment star is completely centered. Once the first star is aligned, it repeats those steps on the second alignment star. Once it has acquired and processed the images of this second alignment star, the scope is ready for use. It is really something to watch, and a thrill when you walk up to the eyepiece to view your first object, without ever touching the telescope other than to turn it on and to tell it the first object you wish to view. All these steps are automatic, and I experienced approximately 10 minute alignment times with my LS 8, that's 10 minutes from powering on the telescope to peering through the eyepiece at my first target.

The LS has true multimedia capabilities built into the design of the telescope with the unique The "Astronomer Inside". In addition to announcing the steps the LS is taking during the alignment process, the most important feature the "Astronomer Inside" adds to the LS 8 experience is its audio descriptions of a variety of astronomical objects. From stats and facts to interesting features, its very informative. As I have used this feature for many months now, I can tell you I learn something each and every time I use it, and I've been into astronomy for almost 15 years. Some folks call it "cheesy", others deem it "fluff", but I find it educational, fun and wonderful for outreach!

Overall Physical Impression Fit and Finish - How did the scope arrive? I won't bore you with describing the shipping boxes, they are exactly as the ETX-LS 6. The telescope has adequate protection, and mine arrive without any blemishes and all its pieces intact. I will say the scope seemed much heavier than the advertised 2lbs difference from the 6 inch model, but then again I did have a back injury in early May and this may still be lingering for me. The container is certainly robust enough to double as an interim carrying case, but again it seems heavier to move around than the ETX-LS 6, so watch yourself and your back.

There were no noticeable dings, scratches or blemishes. Gone is the light blue, non-glossy textured finish of the ETX-LS, Meade has returned the LS series to their trademark navy blue, but has kept a non-glossy texture. I kind of like the old color better, but then again that shade of blue is my favorite color.

Mount - Well, what seemed big for the ETX-LS 6 is quite less substantial for the big LS 8, after all it is the same exact mount. The larger 8 inch OTA has much tighter tolerances, especially noticeable between the lens cap and the base itself (See Picture). Now that is simply a visual description, and by no means should lead you to believe the mount is not adequate for the scope, I'm just giving my honest first impression that the 6 inch seemed much more "comfortable" on this mount. I don't care for the placement of what appears to be the handle area, at the very top of the fork arm, but it's adequate for stabilizing the scope while lifting from the bottom of the base. It's light enough to consider manageable for sure, and it's great to have such a compact telescope for this size aperture. The weight of the scope is manageable, I can even lift it with the tripod attached and maneuver through the door rather comfortably.

Tripod - The scope to me seems top heavy with the tripod, but actual use in the field shows that the tripod, which is the same as the ETX-LS 6, is indeed very much up to the task of supporting the scope and base. It has 3 spring-loaded screws on the base of the tripod, with the center raised to assist in placing the mount on the tripod head, with just a slight twist, I hear a click, and I can now screw the spring-loaded bolts up so they grab into the telescope base, making mounting and setup a piece of cake in the field. There is a plastic wedge that you screw up to strengthen the tripod legs, and it has 3 pre-drilled holes to hold 1.25 inch eyepieces. So as with the ETX-LS 6, the tripod is ok, its ultra light and so very manageable, so I guess that's the tradeoff; lighter weight for less rigidity.

Electronics/Goto - Without a doubt, my very first recommendation is not to consider running the LS 8 off of batteries, get a PowerTank and/or A/C external power supply. Period. I'd get the biggest Powertank you can was well, my Celestron 7amp was adequate for the smaller ETX-LS 6 for up to 6 hours, so I would guess less for the LS 8.

GPS? Drum roll please. For the 8 separate sessions I have used the LS 8, GPS has worked 100% of the time. Alignment process has worked flawlessly. I would say the LS 8 alignment is quicker than the previous ETX-LS 6, one night I was observing in 8 minutes, most nights a respectable 10. I set the scope up, turn it on and go back to getting my star charts out or planning my observing target list and by the time I return the telescope is aligned and ready to go. Either way you look at it, it saves you time in my opinion. The motors seem quieter with the LS 8 and I do not notice any higher pitch when moving in azimuth at certain points with the LS 8 as I did with the ETX-LS 6. I would also like to add that I included testing of the GPS and full auto-alignments from my previous observing location where I had experienced the intermittent GPS with the ETX-LS 6. During one session alone, I tested the automatic alignment 6 separate times from 6 separate spots in my observing area. All 6 alignment tests showed that the LS 8 GPS worked without a hitch. "By George, I think they've got it" was running through my mind as I grinned ear to ear.

I have been getting more and more into double-star observing, and having such an extensive database in the LS 8's AutoStar III that includes star look-up by WDS, HR/HD or SAO references is fantastic. What isn't included in this extensive list, I can always enter the RA/DEC input, and using this has been very easy and accuracy has been dead-on as well. The AutoStar III 100,000+ objects in its database, and most targets I selected were found without any major issues or hiccups. I did experience some initial GOTO inaccuracies during my first two observing sessions, which I'll talk about below, but all future sessions have been much improved.

First light and field testing

A warm evening in June was my first outing with the LS 8. Leo was still visible, and Saturn prominent to the west. Turning the LS 8 on, and within 9 minutes, I was informed my telescope was ready to go. My first target was Saturn, however I had a sinking feeling when I first looked through the eyepiece at what should have been Saturn, but saw nothing. I manually slewed the telescope around, but oddly could see nothing, no image at all, no bright donut, nothing discernible at all in the eyepiece. I then decided to try and focus the image, but the focuser knob wouldn't budge. I was concerned. I thought that perhaps the issue optically was related to something catastrophically wrong with the innards of the scope. I tried to focus again, this time nervously putting more and more pressure on the focus and finally, it moved! "Whew!" The focus was just racked so far in or out of focus that it was at its limits and stuck. Many turns later, I began to see a dim donut image appear in the eyepiece until finally achieving focus, and there was Saturn finally in all its glory.

Now that I have a focused object, and the focuser seems smooth and normal, I thought the image was a bit soft. I turned to Epsilon Lyra, and didn't quite see as much dark space been the Double-Double as I expected. A move to Vega and a defocused star image proves the LS 8 was out of collimation. Another "whew" moment. Putting in a high-power eyepiece I took a few moments to get as collimated as I thought I could do. Pleased with the final results, I turned back to the Double-Double, and was thrilled to see 4 components, this time with well defined dark lanes between them. Turning back to Saturn also gave me the confidence that the optics were certainly good, because the image was nice and sharp.

For the remainder of the evening I tested GOTO accuracy, optics, and some of the multimedia presentations of select objects via the "Astronomer Inside". Everything worked without a hitch. I did experience some GOTO inaccuracy during that first observing session, the first few objects were just outside the field of view of the 26 mm eyepiece, but things improved as the evening progressed. Since that first session, all my future sessions have been much better, with objects within the field of view of the 26mm from the start, and I have found that a quick synchronize to the first deep-sky objects you observe improves the GOTO accuracy immensely, permitting object to be almost center in the field of view of my 14mm UWA. Putting objects in the field of view of a 14 mm eyepiece is darn good if you ask me.

In addition to GOTO, I even shutdown and reinitialized the telescope 3 times that first evening, just to verify GPS and alignment was consistent, and it worked each and every time. Scope was ready in under 10 minutes each time, and with a synchronization to the first deep-sky object, the LS 8 consistently put targets inside the FOV of a 14mm eyepiece.

Further testing the optics: LS 8 ACF optics vs. Celestron Ultima 8 PEC (U8) vs. Orion XT6i

This one comparison excited me. I have been told that my Ultima 8 had some decent optics, nothing ground shattering great, but a fair test of aperture to aperture to the LS 8 nonetheless. Now let me just say, I am by no means an optics expert. My observing skills in this area are intermediate at best, but I will try and convey my thoughts on the process for you below.

Star Test - I used Vega, since it's bright and high in the sky, ideally suited for this kind of test. Defocusing the image showed that the Celestron had equally spaced concentric rings, and appeared to me to have a good collimation. Racking the focus in and out, showed a slight difference in the image, getting slightly diffuse from one to the other. I also noticed that some of the rings at the 7 o'clock position seemed to disappear, so where I had a view of 4 rings, only 2 were visible at the 7 o'clock position. Never noticed that before, but then again, I never really did this heavy of scrutiny before either. I'm not sure what that could be attributed too, but both scopes seemed collimated and both scopes have been out in the elements for the same period of time, so thermal issues shouldn't be the case either.

The LS 8 had better defined concentric rings, they seemed to have a sharper edge to them than the Ultima 8. From what I can view online of what a great star test should look like, the LS 8 matches to them very closely. I also noticed in the LS 8 that there was a similar difference to me from in and out of focus, one had a bit softer and dimmer view than the other, yet the rings maintained their sharpness. I kept the using the 8.8 mm UWA yielding 239x for a simple star field test. This is where I first noticed the visual difference. The stars in the field of view of the LS 8 were sharper and more pinpoint than the SCT at the same magnification. Vega's airy disk pattern was very easy to make out in the LS 8, I really never noticed it so well defined before in my SCT. I was not able to see such a tight image in the SCT, and the airy disks with concentric rings were not as easily visible to me in the SCT either. The bottom line is I prefer the star images rendered at the eyepiece in the ACF then I do in the standard SCT, they simply appear more pinpoint to me. After all that's why ACF and EdgeHD were introduced in the first place, to improve star images by reducing coma inherent in the SCT design.

Saturn - Both the Celestron Ultima 8 SCT and the LS 8 showed a great image of the ringed planet. I could see just a tad more detail on the inner ring, it had a better "edge" to it. There was also better color to the banding on the planet itself in the LS 8 then the U8. Other than that, I couldn't see any other difference in sharpness.

Moon - The U8 had a great image, so did the LS 8. The mare had a slightly darker tinge to them in the U8 actually than in the LS 8. The terminator however seemed to have a bit more "pop" in the LS 8 than the U8. As I scanned the crater floors for the smallest of details and shadows between both scopes, I felt that the LS 8 had a bit of an edge in sharpness of features, but the U8 had some better contrast. Too close to really call a clear winner, at least to my scrutiny.

Oh, and one very neat feature of the Autostar III on the LS 8 as it pertains to the Moon. I never knew that you could select features on the Moon with the Autostar, in fact you have tons of targets, from mare to mountings to craters. It even had the S&T Lunar 100, very nice addition for budding "Lunartics" like myself.

Deep-Sky - I viewed a series of random deep-sky targets, and I think any differences between the LS 8 and U8 were minimal. As far as the star images themselves are concerned however, they just looked better in the LS 8. There were a few standouts. M57 seemed like I could make out the inner definition of the ring itself in the LS 8 easier than the U8. I swear it seemed like I could see more stars with direct vision in M22 and M15 with the LS 8 than with the U8. Comparing the LS 8 to the XT6i may seem unfair, but the optical excellence of the XT6i seems to hold its own. The big difference comes to the LS 8 vs. the XT6i on deep-sky, in particular to my eyes, globulars and open clusters. To some that may not surprise you, obviously the LS 8 has 78% more light grasp, but what I find interesting is that the difference wasn't as striking to me as when I compared the U8 to the XT6i. I guess I just felt the LS 8 image resembled what I have come to prefer in the XT6i, tighter stars. So for deep-sky, the LS 8 ACF is the clear winner vs. the XT6i because of the added aperture. It's not a "wow" effect, my experience has been that I only see that from an increase of 4" of aperture, but I was surprised on how much I noticed the visual difference from a 6 inch optic to the 8 inch with the LS 8.

Now for XT6i vs. the LS 8 ACF on planets, that gets a bit closer. In a nutshell however I think I can sum it up as follows, at least on Jupiter. The XT6i has a tad sharper image and contrast on Jupiter, but the LS 8 ACF has better resolution. Hmm, that falls right in to what should be expected from what I know on optics, the XT6i has a smaller CO, and the LS 8 has larger optics but also a larger CO, so the results are not surprising to me. For instance, the Red Spot Jr. on Jupiter was a bit easier to pick out in the XT6i than the LS 8 ACF, but detail in the NEB was easier to view in the LS 8 ACF than the XT6i. One night of exceptional steady air, I was viewing Jupiter with my 8.8 mm UWA eyepiece, for 239x. Some may say that's no big deal, but I can tell you that here in TN the seeing that permits me to study Jupiter at 239x for long periods of time without the need to swap back to a 14mm for the sharper view, are few and far between. Jupiter had more detail on it than I had ever viewed my whole life, and I was glued to the eyepiece. It was also the first time I was ever able to view actual surface (albedo) features on Ganymede. I knew I'd be very happy with the optics of the LS 8 ACF.

Some dislikes.

Two things annoyed me with the LS 8. One of them is the finder. Its borderline useless. Just like the ETX-LS 6, the red-dot finder has a tinted element that really hinders the ability to view anything but the brightest of objects (Jupiter, Venus, Vega). I really got frustrated trying to initially align the red-dot finder with the LS 8. Why they made it tinted is beyond my understanding, and I hope future versions get a different finder or at least one that isn't tinted for goodness sake. I would also like the have the red-dot led have a dimmer element, it's simply too bright even at the lowest setting.

The second item that annoyed me a bit was how much flexure and vibration existed when focusing. This was most evident with heavy eyepieces, like my 2" 24mm UWA. What I first thought was severe image shift, was simply the ability to "flex" the scope laterally when trying to focus. What seemed to help was using the focuser as close to the back plate as possible, and not trying to focus the knob at the very tip. The amount of vibration present when focusing was higher in the LS 8 than the ETX-LS 6, so much so I immediately noticed it. I don't expect the scope not to vibrate when focusing, but my honest impression here is I just felt it was too much. Just something I'll have to get use to I guess. After all, it's only for those moments I'm focusing, just need to train myself to be careful and work it slow. Note that there is no vibration when the scope is slewing or when it is happily keeping the objects dead center in the field of view. Tap times were about 4 seconds, and vibrations when your focusing leveled out at about 3 or less. I hope the addition of suppression pads will help. The other thing that may help is using smaller, 1.25" eyepieces. I also have a SCT 2" adapter and a Meade Series 5000 2" Dielectric diagonal, so this extends the distance out a bit from the visual back of the telescope even further than the standard 1.25" diagonal that screws directly to the visual back of the telescope and may indeed be contributing to some of the vibrations. I would think that designing the LS 8 OTA to permit balancing would improve dampening time, but not being an engineer, I can only make a logical guess that balancing the OTA would improve the stability and thus reduce vibrations. I have come to accept the need to gingerly focus the LS 8 to reduce whatever vibrations I can, and I have gotten better at it with time. It's still to the point of being irritating, but something that I can live with. To be fair, I see the same thing on my Celestron Ultima 8 when I use a 2" diagonal and a 9x50 RACI finder. Since I don't have counter weight bar, the OTA is out of balance, and even for a very heavy duty mount like the Ultima 8 has, it has an irritating amount of vibration when focusing as well.

Final Thoughts

Overall, after a couple of "whew" moments and a bit of irritation regarding vibration when focusing, my impression of the LS 8 is quite good. Looks like the GPS issues are resolved, and alignments have been a bit faster as well. I like the size and weight of the mount and scope combo for this 8 inch instrument a lot. GOTO accuracy has been good, excellent after synchronization. The optics are great, I thoroughly enjoy the tighter star images and I'm especially pleased to have a telescope that does so well on the planets as well. The extra aperture is indeed noticeable, especially on select deep-sky objects such as globulars and open clusters. I still get a big kick out of the "Astronomer Inside". The AutoStar III still surprises me with hidden features, most recently the extensive Moon features and a Multiple Star listing, although I would sill like to see this searchable under the Constellation than the generic Star menu. I have tested the LS 8 ACF ability to be computer controlled by a number of open-source programs, most notability Stellarium and Cartes Du Ciel, and both worked without a hitch. You may need to wait for software vendors to get caught up to the relatively new nature of the LS, oddly my purchased copy of AstroPlanner doesn't interface with the LS 8 even though the other open-source software has no problem. Paul Rodman of AstroPlanner has confirmed this to be a problem with his software, and I want to thank him and Dick Seymour for all their efforts in assisting me to diagnose the issue. I look forward to a future release of AstroPlanner that has the compatibility issue resolved for the LS series.

In my previous review of the ETX-LS 6 ACF, I wrote that "If someone were to ask me to describe, in one word, my experience thus far with the ETX-LS 6 ACF, the word would be fun". So, how would I describe my experience thus far with the bigger brother LS 8 ACF? Well, it would be two words, Big fun.