Re: How many megapixcels equivalent to 35 mm in quality

David J. Littleboy wrote:

Of course, getting _sharp_ 12.7MP images from the 5D is like falling off a log (at 35mm and longer; corners on superwides are a problem, sigh), but it may be a bit harder to get sharp images on 12MP APS-C cameras, and nearly impossible with 12MP P&S cameras...

I'm not sure - 5d vs APS-C. I've been using both (5d and D300). My comparison of 17-40l @ 18mm vs Sigma 10-20 @ 12mm, the D300/10-20 won for corner performance, edge performance similar. In that case perhaps enhanced by auto CA correction - so that's a possibility for improving edge performance on Fx too. The Sigma lens is 1/2 the price of the 17-40. The 17-40 was certainly sharp enough to bring up moire centre frame - similar to my old D70. In general though, at 19x13", there's no significant difference, D300/5d.
Edge performance at ultra-wide (< 20mm) f/l is IMO an overrated thing. Composition usually means that the 4 corners are at vastly different focus distances - way outside even the huge DOF stopped down. "Normal" wide angle (say ~ 28mm+ ) edge performance can be more critical. YMMV.
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