How to photograph invisible part of the moon?

Started 4 months ago | Discussions thread
Jacques Cornell
Jacques Cornell Forum Pro • Posts: 13,949
Re: 2400WS packs x 1,000,000

Tristimulus wrote:

Jacques Cornell wrote:

Tristimulus wrote:

Jacques Cornell wrote:

and Fresnel lenses on all the heads.

Why?

Fresnell lenses are not quite up to the better traditional lenses and telescopes when it comes to astrophotography...

Fresnels are used to focus the light from a flash or other light source for photography of distant subjects. AFAIK, traditional lenses and telescopes are not readily adapted to this purpose.

Also, my post was meant as a joke.

Yeah - but some new diffractive optics telephoto lenses are based on fresnell lenses.

Have some experience with fresnell lenses for lighthouses. Small light bulb, large fresnell lens, and a brighter light beam than any astrophotographer would want...

How bright would the light from a lighthouse be if reflected from a dirt surface with an area the diameter of the moon? Answer: an almost infinitesimally small fraction of the direct sunlight we see reflected from the same surface. For effective fill, it'd have to be about 1:4.

IOW, it'd be like all those tourists you see trying to light up the Grand Canyon at dusk with the built-in flashes on their pocket cams.

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