I always send the largest file size without up-resing. I'm shooting 24 mp. It's amazing how often the largest sizes are purchased at all my sites. I'm always skeptical of those who "save" larger files for certain sites. I think some folks are doing it to "get back" at sites they think don't pay enough. Anyway, I don't think you can fine-tune that accurately between sites. It also assumes that buyers have a perfect knowledge of the marketplace and spend time comparing sizes and costs between all sites. Never happen. And I'd hate to lose those larger sales. So I think the larger mp sizes you are thinking about will add to sales volumes some. But you may also find you'll get fewer quality rejections because each generation of camera seems to solve lots of technical problems.

I'm at 24mp too. Beyond the larger sizes. the crop space is incredible and images that are questionable for quality can get downsized to 4000-4500 pixels on the long side and go throough happily. hides a lot of sins

the only site I'd consider exclusivity with would be alamy

I always send the largest file size without up-resing. I'm shooting 24 mp. It's amazing how often the largest sizes are purchased at all my sites. I'm always skeptical of those who "save" larger files for certain sites. I think some folks are doing it to "get back" at sites they think don't pay enough. Anyway, I don't think you can fine-tune that accurately between sites. It also assumes that buyers have a perfect knowledge of the marketplace and spend time comparing sizes and costs between all sites. Never happen. And I'd hate to lose those larger sales. So I think the larger mp sizes you are thinking about will add to sales volumes some. But you may also find you'll get fewer quality rejections because each generation of camera seems to solve lots of technical problems.

Very good answer Lou __ my thoughts exactly.

Another HUGE benefit of the larger image is having the ability to both crop the image more tightly or shrink it down to reduce technical imperfections. I often find that I only 'see' the real money-shot in post-processing later and 'zooming' right in with a severe crop can give the final result so much more impact.. As long as I can get a 5MP image out of the shot (so that it still qualifies for Large size at Istock) I am happy. If I'm out and about with my camera I'll sometimes chance upon a stock-worthy subject perhaps in less-than-perfect conditions. Having the ability to shrink down later is often the difference between having a saleable image or a lost opportunity.

I have a 17-40mm and a 5DMII. It's fully capable of handling 21MP. Very sharp in the center but extremely soft at the corners.