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Wally
19-Oct-2010, 21:17
I've read the forum posts regarding 4x5 film plane position and alignment with the ground glass, and there's some suggestion that the ANSI spec (.197 inches +- .007 inches) is explicitly for 4x5.

Does anyone know what the specification is for the film plane in a 5x7 camera? Is it the same?


// Wally

Wally
19-Oct-2010, 21:26
I found these discussions in the archive when i looked further (with better search terms):

http://www.largeformatphotography.info/forum/showthread.php?t=3803
http://www.largeformatphotography.info/forum/showthread.php?t=1320
http://www.largeformatphotography.info/forum/showthread.php?t=1228
http://www.largeformatphotography.info/forum/showthread.php?t=689

and I found my answer in post 6 of the last thread: 5 x 7"= 0.228" + - 0.010

Peter K
19-Oct-2010, 23:31
Does anyone know what the specification is for the film plane in a 5x7 camera? Is it the same?
http://home.earthlink.net/~eahoo/page8/filmhold.html

Jim Jones
21-Oct-2010, 05:16
http://home.earthlink.net/~eahoo/page8/filmhold.html

That link gives 0.228" +/- 0.010" as the distance from the face of the holder to the surface of the film. ASA Z38.1.51-1951 gives it as the distance from the face of the holder to the surface of the septum.

Drew Bedo
21-Oct-2010, 06:48
For some reason I have always thought that the standards for sheet filmholders were the same whether 2x3 or 8x10 format . . .From this discussion, I gather that there is a slight difference for each format . . .?

While these are facinating detailes to me, I don't know how much this matters unless someone is making their own holders DIY. Except for one of the wide formats or ULF, why would someone choose to DIY a film holder?

Peter K
21-Oct-2010, 07:02
For some reason I have always thought that the standards for sheet filmholders were the same whether 2x3 or 8x10 format . . .From this discussion, I gather that there is a slight difference for each format . . .?
As smaller the negative as more it must be enlarged to get a certain image size. So not only the circle of confusion has to be smaller also the tolerances of filmholders etc.

This is the reason for ULF, the film can be at any position behind the lens. :D

jon.oman
21-Oct-2010, 07:47
I've been thinkning of building a 5x7 camera, based on my Shen-Hao.....

Jon

Wally
21-Oct-2010, 10:08
. . .
While these are facinating detailes to me, I don't know how much this matters unless someone is making their own holders DIY. Except for one of the wide formats or ULF, why would someone choose to DIY a film holder?

It's not the case that all manufactured film holders are within spec. So if you find that your shots were sharp on the groundglass but soft in the neg, it's best to do a couple of checks.

First check is to photograph a well-lit ruler at an obliqe angle, focusing on the 6" mark (shows my English units prejudice) very carefully - get your loupe out, adjust very carefully, leave the lens wide open to minimize DOF, let the camera stop vibrating for a few seconds and expose. Develop and look at on light table with your loupe and see if it's the 6 inch mark that's in focus.

If it is, you;ve identified a film holder that you can use as a reference to measure the others against. If not, you may need to measure the accuracy of the position of your ground glass. Refer to the link posted by Peter above to see what the distance is supposed to be - the ground glass should be at the same distance as the film plane minus the thickness of a sheet of film.
If the ground glass position seems to be right, you're on to the next step below. If not, get your camera 'fixed' by someone that knows what they're doing.

Now, for measuring the others, a standard depth guage is not the best tool. You want one of those tools that has a sensitive lever that deflects a dial guage. Measure the known good holder against your others and find out which are keepers and which ones to toss (yes, toss. Don't stick some other poor fool with a bad holder by selling it).

Those links I posted of previous forum discussions describe in great detail how to do the measurements such that the measurement method itself doesn't invalidate the measurement: Some measurement tools will actually deflect the measured surface and give an incorrect reading.

Peter K
21-Oct-2010, 10:22
I've been thinkning of building a 5x7 camera, based on my Shen-Hao.....
Jon, mount a 5x7" back on a conical tube with a baseplate like a RF back for 4x5"-cameras. Than exchange the tube with the 4x5" gg-holder and you can use your camera with both film sizes.

Peter

Drew Bedo
21-Oct-2010, 13:34
Wally: Thanks for the info. Now I am a little inscure about my gear.

When you say that not all holders meet spec, do you mean that quality controme varies from holder to holder within a brand, or do you mean that some brands are better than others? Is there a difference between Lisco or Fidelity? Is there a better (best) holder . . .Linhoff?

Peter K
21-Oct-2010, 14:05
Is there a difference between Lisco or Fidelity? Is there a better (best) holder . . .Linhoff?
There is no difference in quality e. g. tolerances between Lisco, Fidelity and other modern holders. But some old wooden holders don't meet the specifications.

As I know Linhof double-holders, for plates and sheet-films, weren't aviable in 5x7" but only 13x18cm, 4x5", 9x12cm, 6,5x9cm, and 2 1/4 x 3 1/4".

imagedowser
21-Oct-2010, 14:13
There has been an article on holders in View Camera Mag ... can't find what issue, but May/June '01 has one on buying used holders... Toyo holders are ranked higher than most ... here it is ...March/April 1996

Wally
21-Oct-2010, 14:19
Wally: Thanks for the info. Now I am a little inscure about my gear.

When you say that not all holders meet spec, do you mean that quality controme varies from holder to holder within a brand, or do you mean that some brands are better than others? Is there a difference between Lisco or Fidelity? Is there a better (best) holder . . .Linhoff?

If your non-landscape shots (those not stopped down more than f16) are sharp for you then it's probably not something to worry about.

The main issue with film holders seems to be warpage. This is especially a problem for wooden holders, of course, but the metal ones can warp as well.

There's an article on the LFP home page: http://www.largeformatphotography.info/holders.html that discusses these issues.

As for which are best, the older Riteway holders seem to be held in the highest regard (those with the metal pulls), but I've had issues with at least one of each 'brand' (Lisco, Riteway, Fidelity - the three main makers - merged about 25 years ago).

Wally
21-Oct-2010, 14:20
There has been an article on holders in View Camera Mag ... can't find what issue, but May/June '01 has one on buying used holders... Toyo holders are ranked higher than most ... here it is ...March/April 1996

Oh, yeah. I've heard that too. I've never seen one.


// Wally

Drew Bedo
22-Oct-2010, 11:59
Sorry about hi-jacking the thread. Thanks for the Info on holders.

Steve Barber
23-Oct-2010, 01:12
That link gives 0.228" +/- 0.010" as the distance from the face of the holder to the surface of the film. ASA Z38.1.51-1951 gives it as the distance from the face of the holder to the surface of the septum.

The mislabeling of that row would account for the apparent disparity regarding that distance for a 4x5 film holder.

Where it is labeled "Depth to film surface", shouldn't it be labeled "depth to film holder surface"? I don't know the depth for the others, but isn't that depth for a 4x5 at 0.197" and the film thickness considered to be 0.007"? That would be consistent with the part I read where Wisner 4x5 cameras were set up to put the ground glass focusing surface 0.192" away from the film holder supporting surface or 0.190" (the nominal standard) plus 0.002" to allow for wearing down of that surface over time.

If the above is correct, then the label on the drawing "depth to film surface" is incorrect and it should, also, be changed.