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Observatory Parameters
Oct 20
Lat. 39.0, Lon. -77.5
Clouds: Seeing:
New Moon
08:02 19:18

Calculator

Focal Length & Ratio

Focal Ratio

mm
mm
f/

Focal Length

mm
f/
mm

Focal Reducers

mm
mm
f/
f/

Imaging

Camera Resolution

µm
mm
" / pixel

Camera Pixel Size

mm
mm
px
px
µm
µm

Camera Sensor Size

µm
px
px
mm
mm
mm

Dust Shadows / Filter Reflections

µm
f/
px
mm
Did you know the maximum aperture of the human eye pupil is roughly 7mm? You can use this value as "telescope aperture" to find out interesting facts such as our naked eye visual limiting magnitude, or how much more light a telescope gathers compared to our eyes.

Telescope Limitations

Rayleigh Limit

mm
arcsec

Dawes Limit

mm
arcsec

Limiting Magnitude

mm

Light Grasp Ratio

mm
mm
X

Magnification

Eyepiece Magnification

mm
mm
X

Eyepiece for Magnification

mm
X
mm

Eyepiece Real FOV

mm
mm
°
°

Maximum Magnification

mm
X

Binocular Field of View

FOV in Degrees

m
°

FOV @ 1000m

°
m at 1000m

Apparent FOV

°
X
°

Exit Pupil

mm
X
mm

Coordinates

Constellation for coordinates

hr
°

Astronomy Quote of the Day

“For my part I know nothing with any certainty but the sight of the stars makes me dream.” Vincent van Gogh
Astronomy Planning Made Easy. Learn more.