The truth about 24 megapixels
There is a rumour, which the ides of August may stab in the back or elevate to divine truth, that the coming Alpha 77 will have 24 megapixels.
Because of this rumour, there is a lot of very negative discussion going round to the effect that 24MP on APS-C is far too much and the results will be poor (etc).
Well, they may be, if you think Canon’s results are poor – you can judge that for yourself, try a Canon. But they do not have 24MP sensors!
They also do not have APS-C sensors, in the same way that Sony does. They have smaller APS-C sensors with lots of pixels cut off all round the edges. Sony has chunky big APS-C sensors with acres of extra pixels to spare. This is a slight exaggeration of the situation, but hey, I may as well join in the mood of unrestrained opinion!
Facts: Canon’s 18-megapixel sensor makes images 3456 x 5184 pixels in size (give or take a few, depending on your raw processor). Fact: their smaller 1.6X factor sensor measures 22.3 x 14.9mm. Fact: Canon states it is approximately a 19 megapixel sensor with 18 megapixel final output.
Facts: Sony’s 16.2 megapixel sensor measures 23.5 x 15.6mm and into this packs 3264 x 4912 pixels (active area).
If you made a current Canon pixel-pitch sensor the same 1.5X size as a Sony sensor, it would be around 19.7 megapixels active from a 21 megapixel total. If you put Canon pixels on an existing Sony 1.5X sensor, you would be up to 3618 x 5463 pixels and 24 megapixels needs to be 4000 x 6000.
Clearly it’s not the quantum leap some people think, just a quantum leapfrog over Canon’s back with the benefit of the larger sensor. And it’s worth considering that APS-C covers sensor sizes up to a true 24 x 16mm, for Super-35 video use, and that such sensors have already been made. A few wide-angle lenses and zooms might be a bit tight on the image circle, but that half millimetre one way, 0.4mm the other way, adds up to a surprising number of pixels, enough to take the 19.7 megapixels up to 20.7 megapixels without changing from Canon’s current pixel pitch.
So don’t panic. The chances are that 24 megapixels on proper, big Sony APS-C will perform very well. If you’ve got the glass and the technique to make it…
– David Kilpatrick