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Celestron 8" Ultima 2000 vs. Meade 8" LX200 Classic

Pointing accuracy : M8

Definitely superior to C8. Personally I find the fact there is no need to level both instruments to track objects in AZ mode very convenient. In fact I don't need a too high level of accuracy on tracking or pointing thus to level these instruments as I mainly observe the sky visually without need of CCD or very accurate system for long exposures. 

Of course this procedure will be much longer to setup but much more accurate too if you need the highest pointing precision in AZ mode (you have to enter the date/time, location, level the system, etc) or when using the equatorial wedge and polar aligned with accuracy the scope (not available so not tested). According the performance of the electronics this enhanced precision although welcome, is of no use to fit my needs.

Even if both scopes track objects quasi dead center for hours, the M8 software is more accurate. When selecting an object with the M8, it is quasi each time into 1-5 minutes from the field center in the 25mm EP (true field of 37') where the C8 places the object at around 3-8' from center.

The tracking error is minor (15-20 sec) and better than the C8 which pointing accuracy, even using the high accuracy of relative GoTo seems programmed without great attention; in fact it is no better than the standard mode of two-stars alignment, what I deeply regret for such an electronics. So if I forgot something tell me how to proceed.

The M8 centers also an object faster than the C8 but both have found their target within 45 seconds which is fast enough for me.

The M8 is also able to retarget the object to find with a high accuracy by centering a bright star near and pressing Goto again. Better, on the M8 the tracking error is stored in memory (Smart drive uses Permanent PEC) decreasing theoretically the tracking error up to 5" (I didn't test) where the C8 system is manual and without memory from a session to the next (PEC), which can bored some astrophotographers.

Minor problem, the speed switch procedure is quite long and too complex on the M8.

At last, near the zenith both scopes in AZ mode continue to find and track easily their target. I did some test with the stars of Andromedae and M31 successfully as I knew this was a procedure reputated difficult to handle due to the calculation of equations having solution near infinite.

Database : C8

Despite the performances of the M8 software, its Tour mode is to be use with care. The M8 Tour mode has excellent features as a filter on magnitude, quality rating, etc but touring the sky make you crazy as the scope slews from one horizon to another at high speed, waking up your friends and loosing its time crossing constellations to find two objects near in Cygnus for example. A mode illogical programmed I really don't appreciate on the M8.

On the contrary I have found the C8 database of astronomical objects more useful as it comes with foreign catalogs (Abell, ESO). It has more exotic, unknown, but visible objects than the M8 which gathered more numerous (SGVS, SAO, IC, UGC, ...) but also dim, too small or inaccessible objects even through my intensifier !

The C8 database gives also more information and references on objects than the M8, small details which allow you to learn while observing, very useful.

Also interesting, the C8 offers the possibility to store additional objects (25) by entering their coordinates and to add 15 favorites objects in its SkyTour function.

Price : M8

For a similar configuration, including their 12/18V adapter, the case for the M8 and their tripod, in Europe (living in Luxembourg it was easy for me to get prices from UK, France, Belgium and Germany), Celestron 8" Ultima 2000 (and only this top-sales model) is up to 30% (!) more expensive than the Meade 8" LX200 (4100-5100 vs. 4100 ), specially in France and UK.

In the field : C8

Using the scopes during 5 nights among them 2 with quite a lot of turbulence provided insufficient data to complete my tests. Anyway, some directions can be drawed.

The Celestron comes slowly but first for its ease to handle but I can say (but without more technical investigation) both mechanics seem on par.

Looking at low contrasts objects as the C-ring of Saturn, this one was visible on both scopes even on the planet disk with some training. A white band was clearly visible on the limb and near the pole as at least four bands on Jupiter. The Red spot was very light, just discernable but I didn't use (blue) filter. 

On the Moon, Plato's small cratelets (< 3 km) were easily resolved as Triesnecker areas, chaotic reliefs in Apennines and some domes. 

Bright close binary system as a755 near Eta And (0.7") was resolved on both scopes.

Bright galaxies (M31, M81, M51) were easily visible in both scopes even if no necessary recognizable as such, sometimes more fuzzy blops similar to elongated bright nebulae vanishing to the edges.

On the Sun and using a Mylar sheet, the sunspots penumbra was very detailed as the facular area on both scopes and provided a great satisfaction. Of course the conditions were exceptional as the major group was a naked eye object over 100000 km wide.

My opinion

At that price level I 'm restricted to mass produced scopes. Due to the large central obstruction (34% by diameter for C8, 37% for the M8) the optical figure is probably limited to a 1/4-wave P-V which is theoretically enough for such scopes for both visual and photography needs.

In fact, the C8 and the M8 are not really "Ferrari's" in their category. The overall contrast is perfectible compared with the image showed in a refractor of the same aperture. However the Airy disks and the first ring of bright stars are easily discernable. 

A higher quality (over 1/10-wave P-V) cannot be offered to the public without large investment from the major companies since they have to use skilled master opticians. Knowing the commercialization will be limited to the amateur astronomers community, you will pay 3 to 5 times as much as your desired price to use a high quality catadioptric, SCT or MCT.

So the best bet is to put up with the limitations of these commercial designs (field-curvature, large obstruction, etc) and trying to get the best sharpness optic you can find. With luck you can buy a SCT with a 1/8 wave P-V and showing a diffraction pattern with 3-5 rings, both inside and outside focus, with a bright and wide first ring. One of thousands mass produced SCT will have this outstanding quality.

Diffraction patterns of a star. From the perfect image in a SCT to a 33% of obstruction with a spider secondary mirror. Images by the author created with Aberrator.

 Considering the portability, the fact I do few or no photography in high resolution, no CCD needs, the Celestron 8" Ultima 2000 is the best to fit my needs. More, it is lighter and more compact. But test the hand controller for convenience if you don't like small buttons or some complex procedures to reach a submenu or an object.

About price note that even for Christmas there was no discount on this top-sales instrument...

For those who need a high accuracy on tracking DSO's doing astrophotography, intuitive menus to input objects to locate, storage capabilities of PEC, a heavier mount, then the Meade 8" LX200 Classic is for you.

Leave the Celestron 8" Ultima 2000 first to the casual observer who needs a computer-assisted SCT not too loudly and who doesn't worry about some details of target acquisition and accuracy when tracking objects.

This report was read by Alan Dyer who wrote a similar report for "Sky & Telescope". He shares (hopefully) my appreciation.

For more information

Celestron

Meade

Uncle Rod's Used SCT Buyer's Guide (PDF, 7.5 MB)

Celestron 8 Ultima 2000 manual (PDF, 2.3 MB)

Meade 8 LX200 Classic manual (PDF, 1.2 MB).

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