SPN - SPECIFICATION

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Note:

A. These specifications are design drivers. However they will be updated during the design whenever necessary.

B. The specs marked with "=>" are derived from chosen specs, mostly written immediately above.

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Aperture:

250 mm (10"), can be stopped down to 200 and 150 mm (8" resp. 6")

=> Best possible resolution:

250 mm: 0.56"

200 mm: 0.7"

150 mm: 0.94"

=> Usable magnification range:

250 mm: 40 - 500

200 mm: 33 - 400

150 mm: 25 - 300

Focal length:

2000 mm (80")

=> Focal ratio:

250 mm - f/8

200 mm - f/10

150 mm - f/13.3

=> Eyepiece focal range:

80 mm - 4 mm

Obstruction:

<= 15 %

Distance between focal point and optical axis of primary:

190 mm

=> Size of secondary:

250 mm: 32 mm (12.8 %)

=> diameter of fully illuminated area: 9.1 mm

=> FOV of fully illuminated area: 15.6'

=> Time of object in fully illuminated area when not tracking: 62 seconds

=> Magnification for 45 degree fully illuminated view in the eyepiece: > 182

200 mm: 28 mm (14.0 %)

=> diameter of fully illuminated area: 9.9 mm

=> FOV of fully illuminated area: 17.1'

=> Time of object in fully illuminated area when not tracking: 68 seconds

=> Magnification for 45 degree fully illuminated view in the eyepiece: > 167

150 mm: 23 mm (15.3 %)

=> Diameter of fully illuminated area: 9.7 mm

=> FOV of fully illuminated area: 16.6'

=> Time of object in fully illuminated area when not tracking: 66 seconds

=> Magnification for 45 degree fully illuminated view in the eyepiece: > 171

Note: The secondary will be replaceable

Focuser:

Helical low profile.

Spider:

Wire spider.

Tube:

Truss tube with shrouds.

Mount:

Alt/Az dobsonian.