Originally posted by RioRico I corrected my earlier mistake. The 1.5x factor is on the DIAGONAL, not the height|width. So an APS-C 16mpx sensor with the same pixel density scaled-up to FF would be 32mpx. APS-C is very close to 135/HF (half-frame) or 24x18mm, half the area of 135/FF at 36x24mm.

Um, all linear dimensions are scaled the same. If the aspect ratio is the same, then 1.5x the diagonal means 1.5x both the height and width.

**Proof:**
Pythagorean theorem: A^2 + B^2 = C^2 (where A/B are height/width and C is diagonal)

C = sqrt(A^2 + B^2)

(1.5C)^2 = (1.5^2)C^2 = (1.5^2)(A^2 + B^2) = (1.5^2)A^2 + (1.5^2)B^2

therefore:

__(1.5C)^2 = (1.5A)^2 + (1.5B)^2__

Just for reference the K-5's APS-C sensor is 23.7 x 15.7mm (roughly 24x16, a scaling of 1.5 in every dimension). 24x18 isn't even 3:2.

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Last edited by Cannikin; 06-18-2012 at 10:04 PM.
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