Actual Size of Postcard Format - 3-1/4 x 5-1/2 ?

<p>Hi there - Could anyone measure the actual dimensions of a "Postcard" 3-1/4 x 5-1/2 piece of sheet film please? I would like to cut some film but would like to be as close as possible to the correct dimensions of the old Postcard format sheet film.</p>

<p>Thanks,<br>

J</p>

<p>The standard size of a postcard plate (yes I know you are interested in films, but there is a reason) is 3 1/2 x 5 1/2 inches, but the plate was cut 1/32 of an inch smaller than this on each dimension. Film is usually only listed by a nominal size size, ie 3 1/2 x 5 1/2 - but there is no 'standard' alllowance for cutting. I have never cut postcard film, but when cutting 10x8 paper into 4 to fit in 4x5 film holders you need to cut undersize by about 1/16 - 3/32 for it to fit<br>

In the UK the reason for this I believe is that the standard sizes are defined in two different British Standards plates BS1406(1947) and cut films BS1772 (1951). I don't think either is still current.<br>

The reference for this is the Focal Encyclopedia of Photography, Desk Edition, reprinted December 1976</p>

<p>I don't think that there's a hard-and-fast rule about glass plates being undersize. I just measured two 4x5 Wratten and Wainwright plates I used, one is 1/32" under in one dimension, the other is dead-on in both dimensions. The tolerances in cutting glass can't really be very tight.<br>

Sheet film sizes were established to allow the use of film sheaths to adapt them to plate holders. Film sheaths are flat aluminum plates with the two long sides bent over to hold the film. The short sides don't wrap around the film, because that's where the glass plates "indexed" into the film holder. So the film had to be smaller to fit under the bent-over flaps, since the film sheath could not be oversize.<br>

So while postcard sheet film could be as long at 5-1/2", they had to be about 1/16" under-size in width. I don't have an exact measurement since I've never bought any real postcard sized sheet film. I just cut down 8x10" sheets into three postcard size sheets, on a "to fit" basis for my Kodak film sheaths.</p>

<p>The Ilford postcard paper, which is a tad thicker than normal and has postcard markings on the back, is 10x15 cm - nice stuff.</p>