Fresnel? at DVinfo.net

Mike Oveson · February 24th, 2006, 08:36 AM

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.

February 24th, 2006, 08:36 AM	#1
Mike Oveson Major Player Join Date: Jan 2006 Location: Ogden, UT Posts: 349	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.

February 24th, 2006, 12:47 PM	#2
Ben Winter Trustee Join Date: Jun 2005 Location: Hollywood, CA Posts: 1,675 Images: 1	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 :) __________________ BenWinter.com

February 25th, 2006, 05:34 PM	#5
Carl Jakobsson Regular Crew Join Date: Dec 2005 Location: Lund, Sweden Posts: 122	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. __________________ http://www.nattvard.com

February 24th, 2006, 01:44 PM	#3
Mike Oveson Major Player Join Date: Jan 2006 Location: Ogden, UT Posts: 349	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.