On Sun, 31 May 2009 19:04:40 +0100
"Woody" wrote:

Let's split the difference shall we? (36^2+24^2)^0.5 = 43.2.

It seems I succumbed to one of the fundamental laws of Usenet.

(60^2+45^2)^0.5=75 as I said. (This using Windows Calculator.)

The neg size of 645 is more like 56×41.5mm, because 120 film is based
on 2 1/4", not 60mm.

Try your Pythagoras again maybe?

Next time I'll double check before posting. Or just try to abstain
from nitpicking. :-)