Full plate film size

[Bill_1856]

What are the actual dimensions of a full plate negative? (I suppect that 6.5x8.5 is just an approximation, like 4x5, etc). Thanks.

[Sal Santamaura]

This will vary depending on which film holder is in use. Vintage holders and the new Fotoman holders differ* slightly. My Lotus holders were based on that maker's 8x10 holder, then reduced in length and width to accommodate Ilford's and Kodak's nominal film dimensions and worst-case cutting tolerances. Resulting actual image area is 157.6mm x 206.9mm.

*Note that these slight variations are in image area. The new Fotoman holders will match T-depth of my Lotus holders as well as a number of vintage 6.5 x 8.5 cameras.

[Ole Tjugen]

Since all film sizes are based on plate sizes minus a bit for the film adapter sheaths, I would assume the full plate films will be smaller than 6.5x8.5" by about the same amount that 4x5" film is smaller than 4" by 5".

did that make sense?

[Oren Grad]

Do you mean the size of the sheet of film, or the size of the exposed image?

For the sheet of film, my recollection is that the ANSI standard is the nominal dimension less 1/32" for the smaller sheet sizes, and less 1/16" for the larger ones. I expect that Ilford and anyone else who is cutting 6.5x8.5 commercially adheres to the latter as a standard, though cutting tolerances will allow for minor variation around the standard.

The size of the exposed image varies with the holder design.

[Bill_1856]

Do you mean the size of the sheet of film, or the size of the exposed image?

I mean the size of the sheet of film or plate.

[Sal Santamaura]

I mean the size of the sheet of film...

From Ilford's cutting room manager:

Short dimension: 162.7mm to 164.3mm

Long dimension: 213.0mm to 214.6mm


From J&C, referring to Kodak TMY (but I never got film to corroborate):

Short dimension: 163.1mm to 164.1mm

Long dimension: 212.9mm to 214.9mm

[Bill_1856]

Thanks, Sal.