Instruction manual

Appendix C - Technical Specifications
102
APPENDIX C - TECHNICAL SPECIFICATIONS
Optical Specifications
Design Schmidt-Cassegrain Catadioptric
Aperture 8 inches (203mm)
Focal Length 80 inches (2032mm)
F/ratio of the Optical System 10
Primary Mirror
Figure:
Diameter:
f/ratio:
Radius of Curvature:
Material:
Coatings:
Spherical
8
1
/
4
”
f/1.9
32”
Fine Annealed Pyrex
Starbright Coatings - 5 step multilayer process
Secondary Mirror
Figure:
Diameter:
Radius of Curvature:
Material:
Coatings:
Spherical (final hand figuring yields slightly aspheric figure)
2
1
/
4
”
9.7
Fine Annealed Pyrex
Starbright Coatings - 5 step multilayer process
Central Obstruction 2
3
/
4
”
Corrector Plate
Figure
Material
Thickness
Coatings
True aspheric Schmidt curve on one side.
Optical Quality Crown Glass
.190”
A-R Coatings both sides
Highest Useful Magnification 480x ( ~ 4mm eyepiece)
Lowest Useful Magnification (7mm exit pupil) 29x ( ~ 70mm eyepiece)
( ~ 44mm eyepiece with optional Reducer Corrector)
Resolution:
Rayleigh Criterion
Dawes Limit
.68 arc seconds
.57 arc seconds
Photographic Resolution 182 lines/mm
Image Scale ( CCD imaging or astrophotography) 100 arcseconds/mm
64 arcseconds/mm
Light Gathering Power 842x unaided eye
Back Focus 18 ± 5 inches
Optimum Back Focus (f/10)
with optional f/6.3 Reducer Corrector
~ 4”
~ 4” from outside optical surface of the Reducer Corrector
Near Focus standard eyepiece ~ 25 feet
Near Focus with Camera ~ 25 feet
Field of View
with Standard Eyepiece
with 35mm Camera
.65º
.99º x .68º (.62º x .43º - with optional Reducer Corrector)
Magnification
with Standard Eyepiece
with Camera
78x
41x
Optical Tube Length 16 inches
Optical Tube Diameter 9 inches
Front Cell Diameter 9
1
/
8
inches