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-   -   Fresnel? (https://www.dvinfo.net/forum/alternative-imaging-methods/61413-fresnel.html)

Mike Oveson February 24th, 2006 08:36 AM

Fresnel?
 
I will apologize upfront for asking a question that has been asked before. I really hate to do things like this, but so far I haven't been able to come to a conclusion on the difference between a Fresnel and just plain GG? I believe the Fresnel gives a sharper image, but would also require the use of a condenser? Is this right? Sorry. I'm just trying to get the best high quality GG and I think understanding this difference would be helpful.

Ben Winter February 24th, 2006 12:47 PM

A "fresnel" is actually a type of lens. When referring to a "fresnel" ground glass, you are essentially referring to a ground glass focusing screen with a lens on one side that condenses light. No, you do not use another condenser in conjunction with a fresnel ground glass, that's sort of redundant.

The Fresnel lens was named after its inventor, French physicist Augustin-Jean Fresnel. Fresnel is actually pronounced "fernel."

That's what you get from being a techie in high school :)

Mike Oveson February 24th, 2006 01:44 PM

Thanks Ben. That makes much more sense now. From what I have heard from other sources, a commercial groundglass will give you a brighter center with more light falloff as you approach the edges, but a Fresnel will be illuminated evenly across the entire surface. Your thoughts on this? I'm just trying to determine the best thing to use as a GG.

On another board this morning someone mentioned using the Canon Ee-A or Ee-S focusing screens. Both look good, and seem more available than the Nikon D screens. I couldn't find anything about these screens on this board though. If anyone has experience with either of these I'd like to hear it.

Bill Porter February 24th, 2006 01:57 PM

Quote:

Originally Posted by Ben Winter
Fresnel is actually pronounced "fernel."

That's what you get from being a techie in high school :)

Actually it's pronounced "frah-NEL." That's what you get from speaking French. :)

Carl Jakobsson February 25th, 2006 05:34 PM

Look at the illustrations at this page and you'll understand exactly what it is

http://en.wikipedia.org/wiki/Fresnel_lens

I have a Beattie gg, which is a Fresnel, and it's very evenly illuminated. Probably one of the brightest groundglasses you can buy. It's very expensive though.


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