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Fresnel Lens 23 {2 1/4 x 3 1/4}

 
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1banjo



Joined: 16 Nov 2008
Posts: 478
Location: kansas

PostPosted: Sat Feb 04, 2012 8:33 pm    Post subject: Fresnel Lens 23 {2 1/4 x 3 1/4} Reply with quote

I have been looking for some time on ebad for Fresnel Lens
for my Century ! they never come up all I need is the Fresnel Lens
as mine is mising ! I need two so I can put them back in so my foucsing
will be right.

Banjo
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Dan Fromm



Joined: 14 May 2001
Posts: 1881
Location: New Jersey

PostPosted: Sun Feb 05, 2012 12:01 am    Post subject: Reply with quote

Hey Banjo, if you have 2x3 focusing panels made for fresnel and made for no fresnel, measure the heights of the bosses the GG and fresnel (if one is supposed to be there) sit on. The difference between with and without will tell you how much to shim the GG so that a focusing panel made to have a fresnel will focus correctly without one.

I'm feeling lazy and and am doing other things just now. If you don't have 2x3 focusing panels of both types, let me know and I'll check mine, I'm pretty sure I have at least one of each.
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1banjo



Joined: 16 Nov 2008
Posts: 478
Location: kansas

PostPosted: Sun Feb 05, 2012 12:17 am    Post subject: Reply with quote

thanks Dan
I have some that never had a Fresnel & have 2 with out the Fresnel
that need them. I like using Fresnel so I need to find 2 to put back
in the two backs that are missing them so I can go back to using them the way they were to be used!
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Joey Anchors



Joined: 18 Jan 2012
Posts: 63
Location: Philadelphia, PA

PostPosted: Sun Feb 05, 2012 12:47 am    Post subject: Reply with quote

how do you tell if your back had one or not?
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1banjo



Joined: 16 Nov 2008
Posts: 478
Location: kansas

PostPosted: Sun Feb 05, 2012 1:47 am    Post subject: Reply with quote

2 ways # 1 shot some film that you know should be in foucss
and prosses and see
#2 measure the height from a neg. in a film holder to face of the holder
then measure the height from the glass to trhe face of the back
they should both be about the same or about 4.8mm on a 23 {2 1/4 x 3 1/4}

and a back that use a fresnel in front of the Grand Glass
measure's about 3.42mm

BUT some people have add a fresnel to a back that was made for a
fresnel. they need to put the fresnel on top of the glass closer to you out the out side
NOT on the in side like the backs that are made for fresnel in front or on the inside
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Henry



Joined: 09 May 2001
Posts: 1439
Location: Allentown, Pennsylvania

PostPosted: Sun Feb 05, 2012 3:17 pm    Post subject: Reply with quote

I obtained a fresnel, also called an Ektalite screen, some years ago from Robert Pins in NJ (believe he's no longer doing business), and was able to mount it on my Century without altering the position of the gg. I *very* carefully trimmed the edges of the fresnel, which is plastic of some kind, leaving a little projecting tab at each corner. These tabs fit neatly into the cut-outs at the corners of the focusing frame window. The whole "sandwich" uses the original retaining clips and screws as before. The ground glass sits in its original plane, in contact with the frame.

BTW, if you mount the fresnel inside the gg, i.e., closest to the viewer (meaning you, the photographer), and plan on using a loupe, you will certainly scratch the fresnel surface, which is very tender. I wouldn't recommend this practice! I think there is general agreement that the "stacking order" is fresnel smooth side facing lens, fresnel ridged side (the fresnel) against the ground surface of the ground glass, smooth side of glass closest to viewer.

P.S. Dan Fromm, did you know Pins? I think I met him once at a Delaware Valley camera show in Trevose, but I stopped getting his catalogs in the mail some time ago. Is he still around?
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Dan Fromm



Joined: 14 May 2001
Posts: 1881
Location: New Jersey

PostPosted: Sun Feb 05, 2012 4:47 pm    Post subject: Reply with quote

Yes, Henry, I knew Mr. Pins. Haven't seen him for years, have no idea what's become of him.
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