Nope. The Golden Ratio = 1.6180339887...

8.5/6.5 = 1.3076923076...

5x8, 7x11 and 12x20 come much closer to the Golden Ratio:

8/5 = 1.60

11/7 = 1.5714285714...

20/12 = 1.666666666...

The Fibonacci sequence converges on the Golden Ratio

0, 1, 1, 2, 3, 5, 8, 13, 21, 34...

So, in addition to 5x8, 8x13 and 13x21 would be very, very close to the Golden Ratio:

13/8 = 1.625

21/13 = 1.6153846153...

Of course, 21x34 gets you even closer (as does each successive pair in the Fibonacci sequence):

34/21 = 1.6190476190...

Personally, I kinda like the idea of the 7x11 format. Big enough to yield nice contact prints, but small enough to carry in the field.

Kerry