Telescope Calculator

Use this calculator to calculate a few of the more important aspects of your telescope. Fill in the blue/green form and click 'Calculate'. The results will appear in the yellow/orange form. The minimum required information is the aperture.

NEW! There is now a section where you can specify the size and resolution of a CCD imager or DSLR when used in prime focus (with or without barlow lens).

Aperture:   mm or inch
Focal Ratio or Length: f/ or mm
Eyepiece:   mm    
Apparent Field:   degrees    
Barlow Lens:   X    
CCD sensor size:   mm (W) by mm (H)
CCD Resolution:   pixels (W) by pixels (H)

 

Magnification Range:   X to X
Light Grasp:   X    
Resolving Power:   arc sec    
Limiting Visual Magnitude:        
Visual Magnification:   X    
True Visual Field:   arc min    
Exit Pupil:   mm    
CCD Field:   arc min (W) by arc min (H)
Pixel Resolution:   arc sec/pixel    
The above calculations are theoretical limits under perfect conditions. Of course the resolving power of the scope will only be as good as the seeing permits.

The optimal telescope/CCD combination is where the Resolving Power is same or slightly less than the Pixel Resolution.

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