Graflex.org

Lensman · Joined: 20 Jan 2002 Posts: 63 Location: British Columbia

1. Was a Fresnel 'lens' a factory option?
2. Was it available as a 'Do-it-yourself' addition?
3. Are they available now....a Graflex fresnel or ?
4. If available now, can they be installed by a 'Do-it-yourselfer'?
5. Sizes available....and from whom? Prices?

Only thing I found on the Forum was to have the 'ridges' pointing to the lens...(may have missed a topic that answers above...sorry).

jdman · Joined: 13 May 2001 Posts: 302 Location: Midwest

From my book, looks like it was optional on the Century, 2x3 Pacemaker Crown annd Speed. Then on Later Pacemakers was Standard with the the Graflok back. No problem to install your self if you can find one, but reset the Infinity setting. I do not know about availability. Russ

RichS · Posted: Sat Mar 09, 2002 5:38 am Post subject:

jdman · Joined: 13 May 2001 Posts: 302 Location: Midwest

I wish I had stayed out of this one, I have 6 cameras with Ektalite lens (Graflok Back) and I was under the impression the Graflok took into consideration that both the GG and Ektalite would be installed right next to each other. To be truthful, I cannot see a big difference in using the Ektalite. Russ

RichS · Posted: Sat Mar 09, 2002 6:23 am Post subject:

It would take me too long to look up, but I thought there was a Graflok designed without an Ektalite? That was my question for the GVII. How to tell if the back was designed for a fresnel or not. I was worried that the fresnel may have been removed, changing the focusing. From what I remember, the backs are different for the Ektalite. The Grafloks would be designed for them so no need to worry. Unless there was a Graflok designed for no Ektalite and someone put one in? It's too late for me to remember such things

I see a very big difference between no Ektalite and having one in, but mostly in the distortion of the light caused by the fresnel! I'd have to compare the GVII with one of the others, both with a 90mm installed to see if there really is a difference in brightness. The GVII did shock me with it's 'dimness' though, so maybe that's a clue? But from a 135 up, not having an Ektalite is no problem at all and the GVII is certainly bright enough. I actually like it better without the Ektalite! But will probably install one someday just to brighten up the 90?

jdman · Joined: 13 May 2001 Posts: 302 Location: Midwest

Just read an interesting article on Ektalites.
1. There were no Graflok backs designed without the Ektalite installed.
2. The smooth part of the Ektalite faces the GG.
See Google search for a lot of articles on these things. Russ

Les · Joined: 09 May 2001 Posts: 2682 Location: Detroit, MI

The mantra of graflex should have been 'There's an exception to every rule"
The Graflex marketing department was always trying to sell a sightly cheaper camera in hopes that the camera stores could move the customer up to a better one.
Once the Top rangefinder Graphic was firmly intrenched they marketed a camera with a kalart, no viewfinder and no ektalite lens on the back. The handle may not have been the same quality leather. But it still had a graflok back.

if you install an ektalite in a non ektalite back, moving the infinity stops won't help. You will have put the ground glass in a different plane that where the film is.

And I fall into the group that use cameras with and without them. If you use a loupe the fresnel certainly gets in the way.

jdman · Joined: 13 May 2001 Posts: 302 Location: Midwest

You are right, and you would have to shim the GG if you remove the Ektalite, otherwise the GG would be to close to the filmplane. I also found out fooling around making my homemade enlarger and using an Ektalite for a disfuser, that they will not fit down in the recess of a Graphic back. Thanks for your info. Russ

RichS · Posted: Sat Mar 09, 2002 5:57 pm Post subject:

extraparts · Joined: 10 Feb 2002 Posts: 59 Location: texas

Ron Wisner's web site gets into this in detail. He very strongly believes that the Fenel lens be behind the ground glass, not between it and the lens. The fact that argueably the most successful 4X5 camera in history had it the other way, doesn't seem to bother him. However, his site seems to be a very good source of information. My cameras with Fenel lenses have the groves and rough side of the ground glass in contact with each other and the smooth sides out. I suspect that this is a practical consideration (cleaning) not an optical one.

If starting with a camera that wasn't calibrated for a fenel lens, I would probably just install it behind the ground glass and go own. However, as I remember Ron Wisner's web site, he claims that this will still shift the focus away from the film plane. However, he deals in three or for decimal places, to a precision most of us probably don't work to anyway.

Neal

Lensman · Joined: 20 Jan 2002 Posts: 63 Location: British Columbia

Well, having started this, I looked carefully at my GG in my '53-'54 4X5 Crown with Graflok back, and the 'glass' facing the lens has a very fine appearance suggesting this surface is GG. The 'glass' inside the viewing hood is very shiny....obviously this surface, as one views it, is not GG. Also, there are no visible concentric lines indicating a fresnel is installed. So, if there is a Fresnel lurking in there, I can't tell! Besides, the evenness of the image or light, is satisfactory. So, onward and upward!

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[ This Message was edited by: Lensman on 2002-03-09 13:12 ]

patrickcraigmanning · Joined: 22 Apr 2002 Posts: 1 Location: Indiana

In regard to this general topic I was wondering if there is a way of determining if the back on my Crown Graphic (serial#912559) is supposed to have a fresnel lens or not. It does not currently have one, and I haven't noticed any critical focus problems, but it would be nice to know whether the the back is all there or not.

Thanks,

Patrick

Les · Joined: 09 May 2001 Posts: 2682 Location: Detroit, MI

During Pacemaker production there were several variants made as marketing come ons. They would strip some of the standard accessories and market it heavily, hoping of course that you buy the better camera.
At least one of these cameras went back to the side rangefinder, no optical view finder and no fresnel screen.
The frame around the ground glass had to be different that a normal frame because of the thickness of the fresnel screen.
Not having ever seen one of these I don't know if they added a shim or made a different frame.

Because of this it's my belief that if yours isnt' rattling or has something stuffed around the glass then it probably didn't have a fresnel screen.

Henry · Posted: Thu Apr 25, 2002 2:32 am Post subject:

Smooth side of fresnel definitely faces the lens, i.e., the light source; grooves face the "ground" side of the ground glass. This is the way it works in all fresnels, including railroad lanterns, traffic signals, and lighthouses. The light source is on the smooth side, and the fresnel grooves face toward the viewer. But trial-and-error may produce different results! In photography, the chief advantage of a fresnel, I find, is not as an image "brightener," but rather that it evens out the illumination on the viewing screen, i.e., with a fresnel the corners should be about as bright as the center of the image.

The Century 2x3 GG frame has notches in the corners. The fresnel can be cut so as to leave tabs that fit in these notches. This will not change the ground glass/film plane relationship, because the GG position is not changed---thus the focus is not disturbed, notwithstanding the theory advanced by some that the fresnel itself has a focal length and its mere presence will throw off the focus. But my results don't bear this out. I have mounted a fresnel as described, and will be happy to provide details via email. Results are not dramatic, but the illumination is evened out right to the corners of the image.

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[ This Message was edited by: Henry on 2002-04-25 08:11 ]

[ This Message was edited by: Henry on 2002-04-25 08:14 ]

Jim23 · Posted: Fri Feb 21, 2003 12:47 am Post subject:

There indeed was a focusing panel for the Pacemaker 45 that is designed for a ground-glass only (no field lens). The depth from the film plane to the Ground Glass is about 4mm (the same depth as a film holder). With the one that takes the field lens (Ektalite), there is a shallower depth to allow for the thickness of the field lens. Thus, one would have to machine down the surface of the focusing panel (where the Ground Glass rests) to get correct depth and correct focus (there is no compensation for this by adjusting infinity stops, etc. There is a different suffix on the part number embossed in the focusing panel frame for the panel that's designed for GG-only. I'll do some research and post the part numbers for each at a later time.....