Hi All,

Today I visited Orion Optics in Crewe (England), to conduct a test on my
3 months old 8" LX200 f/10 because someone at my club pointed out my
optics were not up to standard. This being my first scope I was not too
sure what I was expected to see regarding "airy rings" and such. All I
was certain was I could not focus properly on bright stars. I was seeing
"comets".

Anyway, the MD of Orion Optics (Mr. Pemberton) invited me to join him in
the testing room. The scope was placed on a bench. The OTA was levelled
and pointed to face at a 12" mirror set on a wall approximately 7 feet
away in line with the OTA. Between the OTA and 12" mirror (approximately
18" from the corrector plate), was a fine metal rod with a small 1/4"
ball bearing glued to its tip. The ball bearing was level with the
centre of the corrector plate.

Protruding from the adjacent wall between the metal rod and the 12"
mirror, approximately 2 feet above the ball bearing, was a penlight
light source whose amount of light was variable by the use of a rotating
diaphram around the lens. This light source was directed at the ball
bearing after the room lights were lowered.

It was explained to me that a Ronchi test was being conducted.

The following is the report on a 3 months old LX200:

1. Overall correction of system is undercorrected.

2. In normal telescope position, there is a small amount of astigmatism
which is pronounced in a crescent shaped zone approximately 35mm from
bottom edge of system.

3. Undercorrection is very pronounced in intra and extra focal star
images. No optimum position of focus is possible. The small amount of
astigmatism tends to produce a 'beard' rather than a 'coma' type flare.

Overall the system is quite poor and is certainly not anywhere near
1/8th wave accurate.

I was advised to return the scope to Meade.

Regards,

Christos

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