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Old 17-04-2006, 08:03 PM
casstony
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Meade LX200R review

Sounds like the LX200R optics might really shake up the SCT world according to this review from the LX200GPS yahoo group:

P. Clay Sherrod wrote:

> I have just completed some testing between both the LX200 SCT and the
> LX200-R and have found several interesting points; although I am not
> going to elaborate in depth on any of these at this time for various
> reasons, I think that you will find the following of interest:
>
> 1) of course, mechanically there are NO changes in the mountings at
> present; there may be in the future.
> 2) field of view: larger by about 15% in the LX200-R over the SCT
> version, even though both operate at f/10
>
> 3) field of view CCD: using the view supplied by the SBIG STV, the CCD
> frame via an f/3.3 reducer (OPTEC) reveals the following:
> Effective focal ratio of SCT - f/3.0;
> Field of view (16" SCT) - 11.7 x 7.5 arc minutes
> Effective focal ratio of LX200-R - f/2.9
> Field of view (16" R) - 13.75 x 8.6 arc minutes
>
> 4) field of view CCD: using the view supplied by the SBIG STV, the CCD
> frame via an f/3.3 reducer (Meade) reveals the following:
> Effective focal ratio of SCT - f/3.0;
> Field of view (16" SCT) - 11.2 x 7.3 arc minutes
> Effective focal ratio of LX200-R - f/2.8
> Field of view (16" R) - 12.8 x 8.1 arc minutes
>
> 5) CCD visual diagnoses of corner field vignetting, estimated in terms
> of light loss: (16" with f/3.3 reducer utilizing photometry of known
> stars in outer 1/4 of field perimeter)
> STC - 37%
> R - 12%
>
> 6) Interesting and related fact to 5) above: in one asteroid field
> test with a defined star field, the SCT offered 8 stars for suitable
> lock-on comparison for both astrometry and photometry via Guide8
> Charon reduction program; the R image of the identical field, somewhat
> larger in coverage in equal conditions, yielded 21 comparison stars
> that Charon automatically and correctly locked onto...this is
> significant for those doing comet and asteroid studies and variable
> star fields. This is a result of both the increased field of view, as
> well as the well-corrected outer perimeter which provides pinpoint
> stars that are not suitable via the SCT optics.
>
> 7) Limiting magnitude, 30-sec. single exposure, dark framed, no moon,
> field of view 12 deg. east of Meridian and celestial equator, CCD
> (STV) using f/3.3 OPTEC reducer: SCT = 17.8; R = 18.4; confirmed
> increase on a variety of similar target shots.
>
> 8) Comment on OTA configuration: although Meade is now providing as
> standard the smooth roller bearings in focusing, the three LX200-R
> scopes that I have seen have considerable focuser backlash (not mirror
> shift, although the shift in the 16 is significant); this backlash
> results from the focuser not being properly torqued to the appropriate
> level, thereby exhibiting wobble and a significant "open space" with
> poor tolerance between the friction surfaces; without this contact,
> the focuser "free-wheels" resulting in loss of focus due to mirror
> weight or gravity.
>
> 9) Comment on collimation: there is a bit more difficulty
> maintaining collimation in the R series than with the SCT, at least in
> the early models; not sure why this is the case, but I have found that
> they are prone to lose collimation (not due to primary shift) as one
> moves the telescope from one point of the sky to one at an opposite
> horizon, suggesting perhaps shifting of the secondary mirror
> collimation system as the scope moves.
>
> 10) Overall.....the star images both visual and photographic are far
> superior in the new R series than with any SCT I have used; the field
> of view is larger, somewhat better define due to nearly uniform
> illumination across the field. In collimation star images exhibit
> textbook Fresnel patterns and in precise focus a very distinct Airy
> disk is seen with two very fine diffraction rings. Note that the most
> obvious impression when comparing star fields is the lack of light
> scatter from bright stars/objects with the R-series over the SCT;
> those of you who are used to seeing "fuzz balls" for bright stars are
> in for a treat.
>
> Fine scope....a big winner over the SCT optics in my opinion. I
> greatly prefer this model over the RCX telescope. It provides the
> best of both worlds: dependability of a non-totally robotic system as
> the RCX is locked into, the beautiful modified RC optics and the
> closed tube design of the LX200 series....hands down beats every scope
> in its class.
>
> You likely will be seeing more on this soon.
>
> Dr. Clay
> --------------------
> Arkansas Sky Observatories
> Harvard MPC H41 (Petit Jean Mountain)
> Harvard MPC H45 (Petit Jean Mountain South)
> Harvard MPC H43 (Conway)
> Harvard MPC H44 (Cascade Mountain)
> http://www.arksky.org/

It's interesting watching these companies duel. I wonder what Celestron will pull out of the hat?
-Tony
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  #2  
Old 17-04-2006, 08:32 PM
beren
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Interesting......wish meade could of brought them out a couple years back
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Old 18-04-2006, 09:00 AM
toc (Tim)
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Quote:
Originally Posted by beren
Interesting......wish meade could of brought them out a couple years back
Point 9 is a bit of a problem though, if its true.
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  #4  
Old 18-04-2006, 09:47 AM
casstony
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I expect Meade will sort out any teething problems; I get the impression that the reviewer has Meade's ear with regard to making improvements in their products. He sounds very experienced and has recently featured in Meade's magazine ads. If the reviewers assessment is accurate the LX200R might even be competition for the Maksutov designs? All very exciting to watch.
-Tony
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  #5  
Old 18-04-2006, 11:20 AM
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astroboy
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Sounds great .
Like to see what its like on DSLR type fields , I think those F3.3 converters only cover a ST7 .
Meade just need to make a good mount for it , and i don't mean that $15K monster , something I can afford .

Zane
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