Graflex Replacement GG/Fresnel Lens

[westpost]

Hi all,

I am new to this forum.

I just acquired a Graflex Crown Graphic and want to replace the GG with a new one, and perhaps a fresnel lens.

1. eBay seller photofinder sells what looks like a fine GG for this camera, and I think I will get that one. Does this make sense? Unfortunately they don’t also sell a fresnel lens.

2. Should I also install a fresnel lens (in front of the GG)? Will the combined thickness of the two cause any problems? From what I can tell, a GG is about 2mm thick, and the fresnel is another 1mm.

3. I see some eBay sellers selling a “2 in 1” combination GG and fresnel lens. They are acrylic. Here is an example: www.ebay.com/itm/265662629997. Are these any good? Worse than the two separately installed?

4. What is better, glass or acrylic?

5. From what I can gather, most 4x5 cameras have a GG that is 127mm wide, while this Graflex is 123mm? I want to make sure I buy the right thing.

Thanks so much! I appreciate any help I can get!

Adam

[Larry Gebhardt]

I prefer glass unless I’m using a wide angle lens. The closer the lens the steeper the light hits the ground glass and the dimmer it appears. A fresnel will bend it back so it’s pointed more towards your eyes, making it easier to see. The fresnel also changes the focus point if it’s in the path before the ground glass. Some cameras are built to accommodate this and others are not. The second one you linked would be appropriate for a camera not designed for a fresnel.

I find the fresnel lines affect my ability to focus slightly and are just a bit annoying. I would test out the lenses you are planning to use with the ground glass you have, after thoroughly cleaning it, and see if you need the corners brighter for any of your lenses. A cheap reading fresnel can be used behind the gg without affecting focus if you want to test it to see how well it works.

[Alan Townsend]

I don't think there is a standard size gg for 4x5. The useful film area is more like 3 3/4 X 4 3/4, or even less if you do your own darkroom work. The graphics with grafmatic back will all use the same size GG. On the Graphic cameras, it's important that the GG focusing surface is 3/16 inch (0.1875) from the portion of the spring back that contacts the film holder. Many used cameras without the stock fresnel/gg that have installed a gg only, do not have the proper spacers in place to ensure this gap, so will give some focus error.

I also agree that reading magnifier style fresnels behind the ground glass work rather well. For a wide-angle lens, you can use a pair of these reader magnifiers, where one would likely work for a normal lens. That's what I do. $85 seems really high for a plastic GG. On advantage of plastic is that it's easier to cut or trim if you have the wrong size. Also unbreakable is good. I use a piece of plexiglass (acrylic) with a sheet of single matte acetate (from art supply) crazy-glued to its surface. This gives a smoother, brighter, and finer focused image, is very inexpensive so you can make several including backups for under $10.

[Kevin Crisp]

If your Crown has a somewhat dim gg, and a fresnel in front of it, with the ridges facing the rear (this is HIGHLY likely on that model) then things get complicated. If you have just a gg, then chances are somebody replaced it or broke the old one. The original fresnel was a Kodak "Ektalite" product; unusual for being in front of the gg with ridges facing the rear.

You can't generally just put an off-the-shelf product in there and expect it to index properly. I have one back that I put a Maxwell screen in -- Bill Maxwell told me due to the Graflex peculiarities I have to get the back machined by somebody he recommended to get it to index properly. I did and it does.

It is really rare to find a Crown without the gg/Ektalite combination. If you can live with it (use a focusing hood, not just the pop-out shade) it works OK. You also have the ultimate bright and clear viewfinder in the form of the hoop action frame that eases up out of the front standard, use it with the rear peep sight which adjusts for parallax. Can't get brighter than that it is accurate with any lens you put on. You can use the bed scale for distance.

[j.e.simmons]

First carefully take the ground glass and Fresnel off and wash them.both on both sides. I was amazed at how much brighter things were when I did it to mine.

[rfesk]

I have used Dawn soap to wash mine with plenty of warm water. And be extremely careful with the Fresnel side. I don't even touch that.

Note: on ground glasses from other cameras the grid marks can be washed off as I found with a Cambo glass once.

[westpost]

Sounds like if there is a fresnel lens in there, I should put in a replacement, and if there is no fresnel, I should not put one in? And that is after I first try washing the fresnel/gg.

By the way, the lens on there is a 150mm 4.5, and it will stay that way.

Thanks

[Kevin Crisp]

Assuming you have a Graflok back, which easily lets the gg come off for accessories like roll film holders, slide the gg and frame off by pushing in on the chromed upper and lower bars to release the two places they hook on. Now look at the camera side of what you just removed. It should feel smooth, but you'll easily the fresnel patterns inside, since the ridges point backwards. If it just looks like a plain 'ol piece of glass, that's what you have.

The point here as far as I'm concerned is that just replacing the fresnel with another fresnel isn't going to make much of a difference. (Unless you go with something really expensive like a Maxwell screen and pay his recommended shop to machine the frame.) And it will probably screw up the clearances so that what looks in focus on what you've changed it to doesn't mean that the same thing is in focus on the film. So you'll have to fix that through experimentation involving removing material in the frame or shimming things until you get it right. To really know what the film is seeing wide open as part of those experiments means you'll have to shoot film to test.

I suspect there were early Crowns that just had plain ground glass, so it isn't impossible that it was always that way. I've only seen that in older 2x3 models.

[Kevin Crisp]

Ektalite shows a pattern when you shine light on it on the back side. Kind of like this.

[westpost]

First carefully take the ground glass and Fresnel off and wash them.both on both sides. I was amazed at how much brighter things were when I did it to mine.

I washed the fresnel and gg and they look much better, as forecasted would happen by multiple posters on this thread. The fresnel is still dim in the corners, but I won't be looking there to attain focus. Now I think that I don't need to purchase a new gg.