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VI SUAL O BSERV I NG
Eyepiece
The optical tube assembly requires an eyepiece to view images.
The eyepiece determines magnification of your telescope.
The optical tube assembly does not come with the eyepiece as
standard accessory unless you purchase a complete telescope
package.
Magnification of the Telescope
Dividing the focal length of the telescope by the focal length of the
eyepiece gives the magnification.
Example:
Using the optical tube unit with SLV20mm or SLV5mm eyepiece.
Eyepiece
Telescope's focal length
625mm (SD81S)
SLV20mm
795mm (SD103S)
890mm (SD115S)
625mm (SD81S)
SLV5mm
795mm (SD103S)
890mm (SD115S)
Note:
Begin with an eyepiece with long focal length (large number in millimeters).
When using an eyepiece with short focal length, the image becomes
dimmer and the range of field of view becomes narrower. Also the range
of sharp focus becomes smaller.
Eyepiece's focal length
Magnification
31.25X
20mm
39.75X
44.5X
125X
5mm
159X
178X
Visual Observing Configuration
Drawtube Lock Screw
(used to hold the drawtube tightly)
Extension Tube VC
EA60mm to 50.8mm SX
(supplied)
Focusing the Telescope
Look though the telescope with an
eyepiece of low magnif ication.
Turn the focus knob for ward or
backward as shown in the figure
until images in the eyepieceʼs field
of view come to focus clearly.
6
EA60mm to 50.8mm SX
(supplied)
Eyepiece 50.8mm
Eyepiece 31.7mm
Flip Mirror Diagonal
(supplied)
Eyepiece 31.7mm
Focus knob
Focus knob
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