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LX90 vs. LX200

gurney

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gurney

gurney

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Can someone tell me what the difference is between a Meade LX90 and a Meade LX200?

And is there much difference between the older classic versions and the newer ACF versions?

For instance if you put a 10" LX90 and a 10" LX200 next to each other, what could the LX200 version do that the LX90 couldn't? And similiarly if you put a 10" LX90 and a 10" LX90 ACF next to each other, what would the difference be?

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Paxo

Paxo

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Gurney,

The difference between the 'old' and the ACF versions are the optics, whether your talking about the LX90 or the LX200. The evolution of the optics on the LX200 went from the LX200 GPS to the LX200R. The R signified 'Advanced Ritchey-Chrétien', a lengthy court battle later they have settled on the LX200 ACF which I think stands for Advanced coma free. To sum up in simple terms these new optics use hyperbolic primary and secondary mirrors to yield a very flat image for eyepice viewing or imaging.

As for the difference between the LX90 and LX200, I have the 12" LX200R, and it's a beast of a machine with extremely heavy duty forks. I have no experience of the LX90 but I believe the basic difference is in the substantial nature of the fork mount. The LX200 also comes with a zero shift micro focuser as well, don't know about the LX90.

THe LX200 is a good telescope but IMHO could have been manufactured better. I have found the need to upgrade the focuser and clutch mechanism, but optically stunning.

I hope this helps.

Steve..

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Tinkerbell

Tinkerbell

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LX200 Better gearing and better forks.

LX90 Much easier to move around.

Classic Easy to use and dependable.

ACF Sales gimmick.

LX90 10" Great for visual.

LX200 10" Great for visual and imaging with the correct wedge.

The LX200 range use much sturdier forks than the LX90, so You gain on stability but loose out on portability.

LX200 uses Autostar 11 which has a much bigger catalogue than the LX90 but if You connect to a computer it becomes accedemic.

Hope this helps a little bit. :thumbright:

Steve beat Me to it :)

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MartinB

MartinB

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I think the ACF is more that a sales gimmick. The field flatness across my QHY8, as measured using CCD inspector, is very impressive, much better than with a standard SCT.

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gurney

gurney

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Lol! Love the smilies you've put there Martyn! brilliant! :)

Yeah, I was reading about the kerfuffle, but I've not actually seen the technical discrepencies between Meade's ACF design and a true Ritchey-Chretien design. Has anyone got any links which show the differences?

And lastly, can I just ask about the LX200 with a 10" OTA ...

Are there any issues with piggybacking another smaller scope like an ED80 on it and a collection of imaging gear? Or is the mount sturdy enough to cope?

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Paxo

Paxo

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There should be no problem piggy backing, however, Meade did 'under engineer' their clutch system on the dec drive and it has a tendancy to slip with heavier loads. The problem is as you load up and have to tighten the lock on the clutch, Meade have put a very small sized bolt and thread to lock and people have found over time that they can damage the threads. There aretwo solutions retap with a coarser larger bolt or upgrade the clutch (clutch supplied has two lubricated surfaces which push together) to a dry system (relatively cheap and easy upgrade to do). This is of course only relevant if you are getting the full scope and not just the OTA andmounting on something like an EQ6 Pro.

I have to admit, I didn't have any problems with my 12" scope, I decided to upgrade the clutch before any problems arose. I'm sure there are others on the forum here who have had no problems as well. One thing worth investing in is a counterbalance weight system, this lestens the load on the drives etc and makes life much easier, especially if you are considering piggybacking another scope and imaging.

Steve..

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ringz

ringz

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I found a picture using piclens so I'm not too sure who took the picture, I just know it's from Flickr. Note the huge counter balance arrangement.

6948_normal.jpeg

(click to enlarge)

--

Martyn

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MartinB

MartinB

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The above photo shows that the system will cope with the extra weight of the guidescope provided you have an adequate counter balance system.

Proper Richey Chretiens don't have a corrector plate, the primary is hyperbolic and very accurately figured to deliver a flat field and deliver a relatively fast system - e.g. F8. That primary mirror is very expensive to make.

An ordinary SCT lets the corrector plate do most of the work (Hence the name), the mirror is a simple spherical mirror - much cheaper. This system deliver good optical results but doesn't have the flat field of the RC, there is a loss of transmission because of the corrector plate and potential for a small amount of chormatic aberration.

The Meade ACF still has a corrector plate. It uses the figuring of the secondary mirror to deliver the flat field. This is a much cheaper thing to do.

The thing is the Meade design is excellent and IMHO delivers a significant improvement in field flatness compared to standard SCT. This is only an issue for imaging with larger format CCDs or DSLRs. I bought a 10" LX200 OTA for just this reason otherwise it would have been a C11.

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winfij

winfij

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I bought a 10" LX200 OTA for just this reason otherwise it would have been a C11.

Indeed - I actually had a C11 and upgraded to a LX200R 10" when I got my 35mm ccd camera.

I did use the new camera (Art11002) on the C11 for a few weeks while waiting for the new bits to mount the new OTA to arrive - the results weren't pretty.

The C11 just doesn't have the flat field or illuminated circle for the big ccd. The coma was very severe as well.

I'd imagine the standard Meade LX200 OTA would be the same.

For the cost, the LX200R is superb - I think they got bashed around by the press a bit much over the whole thing, personally.

John

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gurney

gurney

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And the flat field is what the new versions have courtesy of their 'Ritchey-Cretien LIKE' optics :lol: .. yes?

I think I'll be content for now to have a scope to get used to, then save up my pennies for a 14" lx400!!! :) In my dreams

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