Instructions / Assembly
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MAKSUTOV-CASSEGRAIN OPTICAL SYSTEM (ETX 90)
In the optical design of the ETX 90, light enters from the right through a multi-coated meniscus lens, proceeds to an
f/2.2 primary mirror, and then to a convex secondary mirror that multiplies effective focal length by a factor of 6.3.
The secondary mirror light bafe, in combination with the anti-reection threads inside the primary mirror bafe,
produces extremely high contrast astronomical images at the focal plane.
OPTICAL SYSTEMS
REFRACTOR OPTICAL SYSTEM (ETX 80)
APPENDIX F:
Refracting Telescopes use a large objective lens as their primary light-collecting element. Meade ETX refractors
include an achromatic (2-element) objective lenses in order to reduce, or virtually eliminate, the false color
(chromatic aberration) that results in the telescopic image when light passes through a lens.
90mm
Primary mirror
Secondary mirror
Correcting lens
Focal point
Focal point
Front lens
Eyepiece
Incident Light
Incident Light
Primary Bafe
Dew shield