Kodak Master View 8x10 / 5x7 film plane and GG question

[wuckyboy]

Hello Everyone! - Hope you are all doing well these days. I have a question about film plane registration differing from critical focus on the ground glass:

I have some test shots back from my Kodak Master View 5x7 / 8x10 and I am wondering if anyone out there has ever had to put shims under their GG so that the GG registers at the exact same distance as the film in the film holder. For the sake of this conversation lets please leave out talk of film plane flatness, vacuum backs, and stopping down more to achieve optimal focus / more depth of field.

I specifically want to know if anyone has found that there is a noticeable discrepancy between their GG and their negs. I know that no camera is perfect, and that a tiny bit of wiggle room is to be expected. I'm using Lisco Regal IIs for my 8x10 holders and Fidelity Elite's for my 5x7 holders. I'll add that these holders are in mint condition. I'll also add that my ground glass on the KMV is both original and installed correctly for both my 5x7 backs and my 8x10. The actually real world effect of the problem is that the point of focus in the negatives falls just inches in front of what was the point of critical focus on the GG.

Just wondering if anyone has had to put shims under the GG of their KMV due to slight (but noticeable) film plane registration problems. I'm sure there has been talk on this before. Hopefully you all can give me your insight on this issue :)

Thank you!

- M

[Tin Can]

No.

[Rick L]

just a thought

are the springs holding the GG firm/strong?

if they are a little lose or weak then the holder - being thicker - would be held tighter than the GG with no tension

[William Whitaker]

Inches???

Are you talking about inches behind the camera or inches in front (on the subject side) of the camera?

And to the point, no, I've never had to shim the ground glass on a Kodak Master. I had two of them. They're great cameras to be sure!

[Mark Sawyer]

I have 5x7 and 8x10 backs for my KMV. Both are spot-on. As the backs are cast metal, I'd expect them to be very consistent.

There's a velvet liner that the film holder seats against, and it's very slightly raised above the metal frame. If yours is crushed or missing, that could be an issue, but that would slightly reduce the overall extension, making it focus farther out, not closer in. Maybe someone replaced them with too thick a velvet? Other than that, you got me...

[neilt3]

I have 5x7 and 8x10 backs for my KMV. Both are spot-on. As the backs are cast metal, I'd expect them to be very consistent.

There's a velvet liner that the film holder seats against, and it's very slightly raised above the metal frame. If yours is crushed or missing, that could be an issue, but that would slightly reduce the overall extension, making it focus farther out, not closer in. Maybe someone replaced them with too thick a velvet? Other than that, you got me...

Presumably if the velvet is missing or crushed it will effect where the film holder and focus screen sit equally and make no difference for the point of focus .
It might cause light leaks , but I would imagine that's all.

Does the camera have a fresnel screen ? Or should it have one that's missing ?
If it's been fitted on the wrong side of the ground glass , that would effect correct focus .

[Mark Sawyer]

Presumably if the velvet is missing or crushed it will effect where the film holder and focus screen sit equally and make no difference for the point of focus .
It might cause light leaks , but I would imagine that's all.

True. Does this forum have a corner I can go stand in? :( :( :(

Although the springs would put more pressure on the film holder than on the back, I doubt that it would make a difference.

[Joseph Kashi]

A related question:

I've later added fairly thin (.4mm to .5mm) fresnel sheets between my GG and the GG frame on some older wooden 5x7 cameras. This would seemingly exceed the .01 inch tolerance for aligning GG/film plane depth on 5x7.

Has anyone done any actual testing to see whether offsetting the GG further back from the GG frame by .4mm to .5mm makes any noticeable difference in image quality? The one rough test that I did suggested that there would not be noticeable defocus degradation, particularly given the slight play in most wooden field cameras, but I don't really trust the validity of a single test.

[RichardRitter]

How much is it off?

[robphoto]

re: putting the fresnel underneath the ground glass:

If your camera is set up correctly, the "ground" side of the ground glass should be at the same plane that the surface of the film in the holder ends up at.

Moving the ground glass back from the correct plane by any amount doesn't seem like a good idea.

Can't you put the fresnel on top of the ground glass? (meaning on the side you're looking at, and putting your magnifier against)

[Joseph Kashi]

I put a micrometer depth gauge on the GG holder and noted that the depth was already almost too deep to meet spec, so I removed the fresnel screen and put it on the smooth outside of the ground glass screen. If it scratches too much, it's easy enough to replace. What I did notice is that the GG frame corners needed to be routed out a bit to allow the GG to sit accurately and flat on the frame. The fresnel does definitely help illumination very noticeably and is worth retaining so long as it does not interfere with accurate focus.

Thank you to everyone for your kind suggestions.

[Tin Can]

A thought

OP said his GG is OE

are you sure?

I no longer have a KMV, but the OE GG is very different than any other

working from memory, the OE glass seemed very thin and was not 'GG' aka Ground Glass but a coating in a pattern with clear areas for...aerial view?

[wuckyboy]

Thank you to everyone who responded to this thread. I'm still trying to get down to how this could happen. I'm going to try and reproduce the problem of the focus falling just before the actual subject.

In the meantime take care everyone!

[Ari]

I had a KMV and it came with Lisco Regal film holders.
Right off the bat the focus was off. I worked on the camera, having assumed that film plane registration was off.
Well, after bending the stamped metal back flat and sanding down the area where the GG sits, it seemed to work better.
Later on, I kept having occasional trouble, and found that the film holders varied quite a bit in where they positioned the film plane.
This varied from one side of the holder to the other, and from one holder to another.
Toyo film holders are much better and more consistent in this regard, so I bought a few of those and the film-plane problem went away for good.