What is a fresnel lens?

[Andrew]

Dan,
that is very close to answering one of my outstanding graflex problems.
If you can sort out what number I can expect to see that would be *fantastic* !!!

ps, you have sort of confirmed the idea that the fresnel goes in front when the camera is designed to take it there

[Heroique]

Hello from France...

As a Tachi 4x5 user, I thought I already knew what a Fresnel GG was.

But now I really know!

Thanks Emmanuel.

[drew.saunders]

Hello from France

The name comes from the famous French physicist Augustin Fresnel, one of the pioneers in optics in the XIX-st century. He designed a famous lens system for lighthouses. He proved that you could efficiently focus light by using only a fractionof the weight of a positive glass lens element.

There's even a bust of the man in the Musée de la Marine in Paris!



As a photo nerd, I had to take a picture of it! And, yes, that's a lighthouse Fresnel lens next to him, on the right of the photo, and a smaller one in the upper left.