20"f/3 and 25"f/3 Dobsonian Telescopes: Technical Specifications





Optics 20 Inch 25 Inch
 
Primary Mirror 500/1650mm 635/2000mm
Focal Ratio f/3.30 f/3.15
Thickness of Primary 31mm 35mm
Weight of Primary 11.6 kg 20.3 kg
 
Strehl Ratio Primary S > 0,85 S > 0,80
Interferom. Test Certificate inclusive inclusive
 
Faintest Star @ V=200x 16.2mag 16.5mag
Faintest Star @ V=350x 16.6mag 17.0mag
Rayleigh Resolution Limit 0.23" 0.18"
 
Secondary Mirror 120mm 160mm
Wave PV lambda/12 lambda/10
Obstruction 24% 25%


Mechanics 20 Inch 25 Inch
 
Transport Mode 1 65x66x31cm 78x78x35cm
Transport Mode 2 65x66x56cm 78x80x68cm
Transport Mode 3 65x70x74cm 78x84x85cm
 
Total Weight of Telescope ~ 40 kg ~ 63 kg
Weight of heaviest part ~ 22 kg ~ 36 kg
Weight of Mirror Box ~ 10 kg ~ 16 kg
 
Thickness of trusses 20 mm 24 mm
Length of trusses 106 cm 134 cm
 
Viewing Height Zenith 152cm 182cm


Attachments 20 Inch 25 Inch
 
Focuser 2" Moonlite 2" Moonlite
Reduction Ratio 1:8 1:8
 
Fan for Primary Mirror inclusive inclusive
Secondary Heating inclusive inclusive


Accessories 20 Inch 25 Inch
 
Filter Slide optional optional
Digital Setting Circles optional optional
Counterweight 1kg/2kg optional optional