Opticstar ARC-152 QUAD, Руководство пользователя

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© Opticstar Ltd 2014
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For example when imaging extended deep sky objects like nebulae and galaxies an f/4 telescope will capture four
times the amount of light in the same time period when compared to a telescope with an f/8 focal ratio. The same
does not apply to single point light sources like stars where aperture alone dictates what you can see.
Field Of View
The field of view is the portion of the sky that is visible through the telescope and depends on the focal ratio of the
telescope. In general higher magnifications result in smaller fields of view.
Short focal ratios (f/4) with wide fields of view greatly favour deep sky viewing and imaging, where focal ratios of
f/10 and above are better suited for planetary and Lunar observation. Focal ratios in between these values (f6) may
be considered appropriate for general use.
It is possible to calculate the field of view of a telescope given a certain eyepiece using the following formula.
Actual Field of View = Eyepiece Apparent Field of View / Magnification
where
Magnification = Telescope Focal Length / Eyepiece Focal Length
Consider a telescope with a 1,200mm focal length and a 10mm eyepiece with a 50 degrees Apparent Field of View.
Magnification = 1,200 / 10 = 120 ~ Actual Field of View = 50 / 120 = 0.42 degrees
APPENDIX B
Opticstar ARC-152 Specification
Aperture 152mm
Focal ratio F7.9
Focal length
1,200mm
Objective
Achromatic doublet, can be collimated
Optical coatings Fully anti-reflection coated
Optical tube Internally anti-reflection coated with metal knife-edge baffles
Dew shield Yes
Finder-scope saddle Yes
Focuser type Rack & pinion with lock
Focuser 2” with 1..25” adapter (T-threaded for camera use)
Tube Rings Dual rings with carrying handle and dovetail platform
Tube Weight 10.45Kg (inc. rings)
Tube length 1.270mm
Eyepieces
25mm Plossl
Star Diagonal
90
o
1.25”
Finder scope 9x50 (with bracket)