Korona 4x5 Quandary

[Pritcher]

Hello all, I recently acquired an old Korona 4x5 unit, and am having some issues with it. I must preface all this by saying I am a Graflex SLR shooter, and I have no experience in the world of view cameras. This camera practically fell into my lap, and I figured I'd have some fun with it for what it was worth. After I got the camera, I did some basic things to make it light tight and re-plated some corroded fittings on the focusing rack. I have a big Volute shutter on it as of now. While it isn't perfect and has some issues, it works well enough. The only other unusual part about the setup is that I am using plate mags despite the fact that I am shooting film. The camera came with 2 plate mags, and I have just been taping the film to the mag under a safelight so that it will stay flat and secure in the holder. All that aside, the issue is that despite my best efforts on focusing, I get some very strange blurring on images. Specifically, the center of any given image is completely out of focus, while the edges are crisp and defined. At first I though it was he result of the lens, so I slapped the lens on my Press Graflex and tested it with both the internal and focal plane shutter. That yielded no such focal anomalies, leaving me quite perplexed. Attached below are a couple links to scanned examples from both the Korona and the Press Graflex. I tried to use the forum image system, but it compressed the images very harshly, to the point of details being unrecognizable. Any input or suggestions for solving this issues would be greatly appreciated.

Cheers

https://drive.google.com/file/d/1TygUmcGV22KnNqnBPV5JTl7sJ0OX3jhv/view?usp=sharing
If you look at the grass in the foreground or the hedge about center, you can see how as you go from edge to center the grass becomes less focused.

https://drive.google.com/file/d/1eh2y4wq_vs1fmhoh1hNn65qEAzKlzp8P/view?usp=sharing
It is the same story with this one, the grass says it all. On the ground glass I was sharply focused on the tree, and I really don't know how it could have been that off.

https://drive.google.com/file/d/1DGOBRvEe_FR1OWRMPOo2UZmZgrUWSjKb/view?usp=sharing
This is the control from the Press Graflex, it was taken using the internal shutter just as the rest were, yet it lacks the focal artifact.

P.S. Might anyone have some compatible wood film holders? I am only familiar with the Graflex slotted holders, and I really havn't a clue what I am looking for to feed this camera.

[Vaughn]

I assume "plate mags" means plate holders for camera instead of film holders. I can't see the images.

You are off the thickness of the glass plate with your focusing. The GG and the plate holder work together (one replaces the other) to be positioned so that the frosted side of the GG is on the exact same plane as the top of the glass plate (where the emulsion sits). Placing the thinner film in the plate holder puts the emulsion further away from the plane the GG is on. It is a significant distance -- as is the flatness of the film in the holder.

Most makes of plate holders had metal inserts for using film (film sheaths), and they should be semi-exchangable since they are designed to mimic the same thing -- a glass plate. One loaded a sheath with a sheet of film, then put the sheaf into the plate holder as if it was a plate.

Here is an old post I just grabbed to show a quick image of one...

https://www.largeformatphotography.info/forum/showthread.php?161503-Metal-Film-Sheaths-how-to-make-them

PS -- or order some glass plates...:cool:

[Pritcher]

Whoops, guess I got my terms mixed up. I am so used to saying plate mag because that is what I use on my primary camera. I meant to say film holder there, apologies for the confusion. I have a full set of film sheaths for my 5x7 plate mag, though I would be hard pressed to find one for this specific 4x5 holder. I see what you are saying about the thickness not being right for the film, and I too had thought about that. However, why on earth would it only be the center that was out of plane? Surely any minor variations in the holder's height would not grossly effect the center focus of the image while leaving the edges symmetrically crisp. And yes, I do someday want to get some glass plates to shoot with, but I haven't gotten there quite yet lol.

[Two23]

Totally agree with Vaughn. You can't use the 4x5 holders you already have from the Graphlex, or are those not the standard type? Buy a couple modern holders. They are cheap enough.



Kent in SD

[Jim Noel]

All you need is some standard (modern) film holders. I bought my wife one of these cameras several years ago and the holders worked perfectly. They should have a ridge, not a groove, for the light trap.

[Vaughn]

I have the same camera in inoperable condition (and missing the back altogether.) and what might be the original lens/shutter mounted on wood from a cigar box. A Bausch and Lomb Series D (from the size and old catalogs, for 4x5).

I thought perhaps the film may not have been taped in flat. I would check the distance from the edge of the holder to the film plane, and the equivilent on the camera back...see how close they are. I would also double-check how square the camera is, make sure it hasn't skipped a gear. Good luck!

PS -- if the images are too large, the site auto down-sizes them, and not too nicely. I think the site likes 1000 pixels on the longest side.

[Pritcher]

I would also double-check how square the camera is, make sure it hasn't skipped a gear.

Boy oh boy has this thing skipped gears on me. At one point while I was working on the plating, it was 3 or 4 teeth off level. I have eyeballed it to get it back on an even keel before taking pictures, but didnt do anything more. Ill take a level to it and see if that fixes the problem.

[Pritcher]

You can't use the 4x5 holders you already have from the Graphlex, or are those not the standard type?

Yeah, Graflex slotted holders are a completely different design. Plus, I have never had a 4x5 before, I only own 3¼x4¼ and 5x7 holders.

[Pritcher]

They should have a ridge, not a groove, for the light trap.

Yeah, I see how these old plate holders have a ridge near the top. Now I am having a heck of a time on EvilBay finding ones that look like that which aren't plate holders. Is this just a really outmoded design? or am I simply looking in the wrong places?

[mdarnton]

Regarding keeping the standards straight: they might get off every time you open the camera, but the knobs should be spring loaded--pull the knob out and it disengages the gears allowing you to straighten the standard easily. That's how my 5x7 works, anyway.

Standard 4x5 holders have the ridge. They would be what would normally turn up if you search 4x5 holder, and there should be hundreds for sale on Ebay. Even modern plastic holders should fit.

[Chauncey Walden]

Of course, this is assuming that the camera body has a groove and not a ridge. Old can be ridge on camera and groove on film holder and new is groove on camera and ridge on holder. Two grooves or two ridges are a problem.

[Rod Klukas]

The prevelant film holders of today won out, because the ridges on Koronas tended to wear out or get knocked out after use over time. Every shot wore on the camera. With a holder it only gets stressed when that holder is used. By the way, currently the 4x5 Toyo holders are the most consistent and accurate of any out there in that size.
I may have missed it, but as all image projections are spherical, not flat, you might have tried one at F64 or more. That should have created enough depth of focus to get you closer. But the suggestions above are quite good, anyway.