Clear aperture ----- 300 mm
Central obscuration ----- 165 mm or 55%
Optical quality ----- Diffraction limited
Primary and secondary mirror coatings ----- Enhanced aluminum
Field corrector lens coatings ----- Multi-layer anti-reflection coatings on all surfaces
F/4.9 field corrector ----- 70 mm diameter three lens system
F/9 field corrector ----- 70 mm diameter three lens system
OTA length ----- 516 mm (20.33")
OTA width ----- 414 mm (16.3")
OTA weight ----- 50 lbs - approximately
Carbon tube ----- 15.3" diameter
Primary substrate ----- Fused Quartz 12.5" diameter
Secondary substrate ----- Sital 6" diameter
Back focus at f/4.9 ----- 183 mm (7.2")
Back focus at f/9 ----- 300 mm (11.8")
Focal length at f/4.9 ---- 1,470 mm
Focal length at f/9 ----- 2,700 mm
Field of view - linear ----- 55 mm diameter at f/4.9 ----- 55 mm diameter at f/9
Field of view - angular ----- 2 degrees diameter at f/4.9 ----- 1.2 degrees diameter at f/9
Vignetting* 42 mm image circle ---- 0% at f/4.9 ----- 0% at f/9
Vignetting* 55 mm image circle ----- 13% at f/4.9 ----- 5% at f/9
*assumes no adapter/filter obstruction