Originally posted by jon404 Need 24 MP? Well, you don't, until you do. For web use... or for 300dpi printout of what, 8 x 12 images... no, you don't.
But. There's a cloud in our happily lo-res sky. Apple's 316 ppi Retina display. Marketing hype, to be sure... the human eye can't resolve anything over 250 ppi... and, taking advantage of this, here come the iPad competitors.
Me? I'm retired. But if I were still working (web design, e-learning development) ... I would be following the new screens with great interest. Think about it. The laptop I'm using tonight has what, 96 ppi screen resolution? So a 2-or3 MP image is more than enough to fill the screen. But -- double that resolution, and how many web pages will have to be re-worked? Aarrgghh! As for print, that's far less of a problem, since you're sending 300 dpi -- at most 600 dpi PDFs to printers using technology that changes very slowly. But on the screen side, the web side, the mobile devices side -- watch out! You won't want your viewers to swipe-enlarge that 2 MP image and have it pixelate right off the screen.
So -- grudgingly -- 24 MP. 30 MP 36 MP. Pixels dancing on the head of a pin. But plenty of room to crop, and still have a hi-res image. Just set aside a lot of money for that new camera, and a new PC fast enough to process those gigantic new RAW files!
ANd that is probably the sad reality of the situation....my whole argument against FF was unless your computer screen was more than 2500 pixels wide, you probably wouldn't see the difference. I know people think they can, usually people who know which image is whcih before they make their judgement, and I hope I don't have to explain how flawed that type of evaluation can be. Last time I was in the computer store, the guy offered to set me up with a multi-processor hackintosh and a korean 4000 pixel wide screen for a total of $1200. I thought, "the future is here." I already need 8000 pixels across to do a 1:2 reduction. And unless you're shooting with a Foveon sensor you probably need that 1:2 reduction. The computer technology is already ahead of the cameras.
On the other hand the resolution of a D7100 is 6000 x 4000. SO what we're actually talking about in real terms, is the ability to crop 1000 pixels each way to end up with an image the same size as your 4900 x 3200 K-5 image. You don't get that much for adding 8 MP. I Know some think that's a lot. I tend to think exponentially. When a technology doubles, that's a lot. A 20% increase in width, is not a lot.
I'm looking for the 80MP 645D, now that would be a lot. A 36 MP D800, now that's a lot. 24 MP, is more of an incremental shift.