dimensions of 4x5 format?

[dh003i]

I have put the old lens specs on this page into Excel format, and am doing the calculations for the values listed in the new lens Excel sheet, but not in the old lens specs.

To do many of those, I need the diagonal of the 4x5 format. I calculate it as being 163: 25.4 x sqrt(4^2 + 5^2). However, the Excel spreadsheet for new lenses says the diagonal is 153. That seems incorrect to me...unless the dimensions of the 4x5 format aren't actually 4 in x 5 in, but slightly smaller. Is this the case?

[Jay Wolfe]

Yes, of course.

[dh003i]

Yes, of course.

Of course what? My calculation is right? Or the premise of it (that 4x5 is actually 4x5) is wrong?

If 4x5 is slightly smaller, what are the dimensions?

[aduncanson]

Film holders mask off about 1/4 inch in each dimension. I suggest that you measure a neg.

[Kirk Fry]

3 3/4 X 4 3/4 if you don print the very edges, you film holders my vary.
my diagonal measures 154 mm more or less. The film is not even 4 X 5. Inflation set in.
(I suppose they want it to fit in the film holders.) K

[Ole Tjugen]

The sheet of film is slightly smaller than nominal 4" by 5", and the film holders mask off a little bit too.

Glass plate negaives were "full size", but when film was introduced they were made a few mm smaller on both sides to fit in metal cut film adapters for old plate holders.

So your calculation is correct but inappropriate.

[Peter K]

All the negative formats like 4x5", 5x7", 8x10" and also the metrical formats are glass-plate formats. The sheet-film formats are always smaller because the film has to fit together with the sheet-film-insert in the plate holder. The image size, not the film size of 4x5" is 94,4 x 120mm.

P. S. Ole was a little bit faster

[Emmanuel BIGLER]

The actual size of the image on a 5x4 film as Peter says is about 94x120 mm.
For a 9x12 cm, similarly you have to take about 6mm off (3 mm off each side) this yields 84x114mm for the good ol' European metric format.

[timparkin]

The image size on my Ebony using a Fuji Quickload holder is 96x120

[Frank Petronio]

I take it that you are working from the spreadsheets found here? http://www.largeformatphotography.info/lenses/

There are more concerns that image circle when selecting lenses. Also, the quality of the lens at the edges of the image circle varies, so while a lens may "cover" it may not do it as well as others.

Most people choose lenses based on real world recommendations, word of mouth, reputation -- all easily searchable on this forum and elsewhere.

Our friend Christopher Perez made this chart, which should give you something to ponder:

http://www.hevanet.com/cperez/testing.html