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Old 19-06-2010, 08:11 PM
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5ash
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equivalent magnification

I am using a barlow lens on my telescope with a G star camera and find the width of the field of view is about 8 arc seconds. How do i determine the equivalent magnification to that using an eyepiece.
regards philip
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Old 20-06-2010, 10:22 AM
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Magnification is pretty irrelevant term in photography...
We are actually dealing here with "scale" : pixels/arcsec or arcsec/pixel or equivalent (in the times of film photography it was mm/arcsec or arcsec/micron).
You already know the FOV, so it is not hard to calculate the scale you have with your camera and your telescope.
Magnification is meaningful term in case you are comparing two values of the same dimension - in case of visual observation, it is the ratio between apparent angular size of the object in the sky (visible by the naked eye) and apparent angular size visible in eyepiece, and it is given by the ratio of focal lengths between objective lens (or mirror) and eyepiece.

Last edited by bojan; 21-06-2010 at 08:37 PM.
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