What is the Meade LX200R?

It works at f/10 and looks like a regular LX200 so is it more than a wide-field RC corrector plate? Intregued! See www.telescopehouse.co.uk/

Nytecam 51N 0.1W

"nytecam" wrote in message
...

It works at f/10 and looks like a regular LX200 so is it more than a
wide-field RC corrector plate? Intregued! See
www.telescopehouse.co.uk/

Nytecam 51N 0.1W


--
nytecam

Meade don't say an awfull lot about the RC design. A search dug this up
though. Thought it might be worth sharing?

http://www.astronomy.com/asy/default.aspx?c=ss&id=9

Ritchey-Chrétien
This telescope design was developed jointly by American optician George
Willis Ritchey (1864 - 1945) and French optical designer Henri Chrétien
(1879 - 1956) in the first decade of the 20th century. These two telescope
designers found that the lower the amplification factor of the secondary
mirror, the flatter the field. The Ritchey-Chrétien system has a secondary
mirror that magnifies 2.7x, whereas the Schmidt-Cassegrain design has a 5x
secondary. The Ritchey-Chrétien design is coma-free, whereas the
Schmidt-Cassegrain is not. Ritchey-Chrétien telescopes have hyperbolic
primaries and secondaries that correct for coma; production-type
Schmidt-Cassegrains use a spherical primary and secondary and do not correct
for coma. Finally, the Ritchey-Chrétien design has two optical surfaces. All
Schmidt-Cassegrains have four. Why are Schmidt-Cassegrain telescopes more
popular (by far) than Ritchey-Chrétiens? One word: price. A Ritchey-Chrétien
telescope is quite costly to produce and, therefore, expensive to buy.

Regards


Chris

nytecam wrote:

It works at f/10 and looks like a regular LX200 so is it more than a
wide-field RC corrector plate? Intregued! See
www.telescopehouse.co.uk/

Nytecam 51N 0.1W



There has been considerable discussion about these new scopes amongst
various groups to which I belong, I have attempted to distil the
collected wisdom from these discussions below.

Calling these (and the RCX line) Ritchey Chretien designs is a marketing
ploy by Meade; by definition a catadioptric scope cannot be an RC. In
fact the design is an optimised SCT and as such is to be welcomed since
it offers improved performance (compared to an SCT) at an affordable
price. A true RC design remains expensive to realise due to the
requirement to create 2 hyperboloid mirrors to a high accuracy.

All of the Meade LX200R and RCX scopes appear to employ a spherical
primary, an aplanatic secondary and a thick corrector plate. The optics
seem to be a modification of one of the optical designs investigated by
Sigler in the 1970s. To execute the new design the optician makes the
secondary a prolate ellipsoid by removing a couple of waves of glass
from a spherical secondary, and then slightly changes the figure of the
corrector plate from the standard SCT prescription. So while they are
not an RC optical configuration, they are an advance on SCT optics. The
resultant optical design has optical correction somewhat similar to a
true RC scope, i.e. elimination of coma, but does have considerable
chromatic aberration, introduced by the corrector plate, and the
curvature of field associated with the standard SCT design remains.

So, whatever you call them, they are a significant improvement over the
standard SCT: the RCX scope are f 8 versions of this design whilst the
new scopes are f 10 versions of the same design. The new scopes have
the "pseudo RC" optics in the standard GPS tubes and are available in
fork mounted and OTA only versions.

Regards
--
Derrick Farley
http://www.lh-dome.demon.co.uk/

"Derrick Farley" wrote in message
...

SNIP
So, whatever you call them, they are a significant improvement over the
standard SCT: the RCX scope are f 8 versions of this design whilst the
new scopes are f 10 versions of the same design. The new scopes have
the "pseudo RC" optics in the standard GPS tubes and are available in
fork mounted and OTA only versions.


It would be interesting to put one up against the Vixen VC200L which has
been around for years and has a significantly better flat field and off axis
performance compared with the SCTs

Robin

"Robin Leadbeater" wrote in message
...

"Derrick Farley" wrote in message
...

SNIP
So, whatever you call them, they are a significant improvement over the
standard SCT: the RCX scope are f 8 versions of this design whilst the
new scopes are f 10 versions of the same design. The new scopes have
the "pseudo RC" optics in the standard GPS tubes and are available in
fork mounted and OTA only versions.


It would be interesting to put one up against the Vixen VC200L which has
been around for years and has a significantly better flat field and off
axis
performance compared with the SCTs

Robin
In the F/10 version, the field curvature on these Meade 'SCT-GT' scopes,
will be poor (the RCX units, have a slightly less agressive primary
curvature, and give better field curvature performance). I must admit I am
suprised that Meade has not launched a field flattener for the scopes.
Something priced in the order of their focal reducers, that flattened the
field on the RCX, and on these newer scope, is an essential accessory for
larger CCD's and film use, which is still missing.

Best Wishes

Originally Posted by Robin Leadbeater

"Derrick Farley" wrote in message
...

SNIP
So, whatever you call them, they are a significant improvement over the
standard SCT: the RCX scope are f 8 versions of this design whilst the
new scopes are f 10 versions of the same design. The new scopes have
the "pseudo RC" optics in the standard GPS tubes and are available in
fork mounted and OTA only versions.


It would be interesting to put one up against the Vixen VC200L which has
been around for years and has a significantly better flat field and off axis
performance compared with the SCTs

Robin

Interesting Robin - how much are these improvements due to the VC200L 3-element corrector before the drawtube?

Nytecam