The exact dimensions of the rectangular 4x5' film area that gets exposed?

I am interested in drawing some gridlines on my 4x5' ground glass. I would like to know the rectangular dimension of the 4x5' film that actually gets exposed (i.e. area that is not blocked by film holder guides/flap) and how they relate to the orientation and placement on the whole 4x5' film sheet. Does this vary with different film holders? Ie. I would like to know the exact rectangular dimension I should be composing to to include everything on the film.

To the best of my knowledge, the area of film which is actually exposed in classical 4x5" film holders is about 6 mm (1/4") smaller than the total film size
Hence, allow something like 94 x 120 mm for a 4x5" film (4x5" = 101.6 x 127 in theory, but the actual film support area can be a bit smaller)
On the film side corresponding to the small flap you have to lift to slide the film inside the holder, with certain holders, the image is exposed almost as wide as the film support itself, this gives a kind of a "signature" to images taken with a 4x5" camera ;)

The dimensions of 94x120 mm might depend on the film holder brand, but probably not more than by one millimeter.

P.S. simply check with a ruler on your next sheet of exposed & processed film ;-)

This might be a little different with different brands of film holders. I would measure it and note that the film may have a few microns of movement within the film holder as well.

Schneider says the image area is nominally 96x120mm. But in practice it can vary slightly across holder types. So what Emmanuel said: measure one of your processed sheets.

A different issue: in many cameras, there's a bit of play in where the holder is seated when you insert it. Where that is true, there is no assurance that where the film window sits will exactly match where you've scribed the lines on your GG. If that is true of your camera and holders, and if you must have as close a match as possible, you may need to do some trial-and-error measurement and shimming to get your camera set up exactly how you want it.

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Originally Posted by Robert Hall

I would measure it and note that the film may have a few microns of movement within the film holder as well.

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If the concern is to get on film exactly what is in the scribed area on the GG, this doesn't matter - all that matters is that the opening in the holder be aligned with the marked area on the GG.

What follows won't be of any help to any 4x5" user, but It happens that I have, handy, a 9x12 Linhof film holder, a model very simliar to a Fidely holder. The actual image area is 84x114 mm (i.e. 6 mm less than the nominal film size) with a band of 21mm long being totally exposed across the whole film width, on the holder side where the film slides in for loading.

The exact registration of the film gate with respect to the optics is something that was addressed by Schneider with their system of high-precision 4x5" holders. If I remember well, the price of the system was about ... an arm & leg, so my understanding was that most 4x5" users, eventually, decided that the good 'ol' Fideltiy holder was exactly what they needed ;)

To me the fact the the film can be somewhat "floating" inside the holder, plus the erratic placement of the holder itself at the back of the camera, has no real consequence, except for very precise framing, and of course for people who asked Schneider to develop their precision film holder sysem; and, may be, this fuzziness is a real nuisance for some eccentrics I know personnally, doing tri-color images from 3 sheets of B&W film.
When scanning their 3 films, they can have all possible effects of mis-registration between their 3 images, parasitic translations AND rotations, rotations being more tricky to compensate digitally ... rollfilm holders being potentially less annoying since you simply have to advance film between the 3 images, without taking the roll holder off the camera: in principle, parasitic rotations should be minimal in this approach ...

If I measure mine and post it will that help you if we don't use the same brand film holder? Can you just measure your own?

An idea...

Slip a piece of white paper into a film holder, put the holder in the camera back, remove the camera back from the camera, and then mark the corners on the GG (on the side that normally faces the lens) where you can see the white of the paper that is in the holder. Use these dots to draw temporay lines on the back side of the GG (the side you look at when composing).

Test the accuracy of the lines by photographing a grid pattern and making sure that what is on the negative matches exactly as you framed the grid pattern image on the GG.

If you have different brands/models of film holders, you can load white paper in them to double check how they line up to each other by repeating the first part above.

I have a Lisco 4x5 holder on my desk, and it is 3.83" (97mm) by 4.75" (121mm).

In my Sinar back, the edge running along the insertion slot is aligned with the edge of the frame opening, but the frame opening is 1 or 2mm more open on the other three edges. The Lisco holder has about 1mm of slop. The Sinar ground-glass frame is 3.69" (94mm) by 4.70" (119.5mm).

If you drew all these rectangles on top of each other, they would align at the insertion edge.

Your camera will be different.

If I needed frame-edge precision, I would draw a frame slightly in from the edges (maybe 2mm) and crop to that frame line. That will accommodate all the variability between holders and holder positioning slop.

Rick "ruler in hand" Denney

In the past two or three years I've bought quite a few more 5x4 DDS and I've noticed quite a significant difference with some of the older ones. I discovered that the early Graflex & MPP film holders are actually plate holders with film inserts some glued in others riveted in, these have a smaller image area than more modern holders.

Ian