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View Full Version here: : Why is 2x50mm or even 7x400mm not possible ?


skysurfer
22-11-2013, 07:06 PM
Optical laws dictate a minimum magnification of the aperture divided by the eye pupil diameter (5..7mm). That makes small telescopes view things which are not possible in larger ones. This inhibits experiencing stunning views of deepskies like on photos.

E.g. a 40cm Dobson with 7x power should show Eta Carinae or M42 visually in full color and even large faint objects like the North America Nebula or even IC1396 become easily visible in such a setup.
Is there no way to circumvent this limitation, otherwise than using light amplification devices such as night vision goggles ? In the latter case you watch a screen rather than directly.

cometcatcher
23-11-2013, 07:54 PM
Get a transplant with cat's eyes?

Satchmo
23-11-2013, 08:59 PM
Fact : If you fill your night adapted ( 6-7mm ) pupil with light from a telescope with any given aperture - the surface brightness of an extended object does not change, only the magnification.

The surface brightness of the Great Orion Nebula appears the same naked eye as it does in a 10 meter aperture telescope assuming appropriate magnification is chosen so that your maximum pupil is just filled by the telescope.

Its tough being human sometimes :)