The truth about 24 megapixels

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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



  • I think there will be APS sweet spot advantage with FF lenses. It’s a FF which demands corner sharpness. In addition, I remember David once show that A900 per pixel sharpness is worse than A550 and it is not about lenses.

  • Hi David. With my better Minolta lenses I see mosaic shaped artifacts around fine details in RAW files from my A200: the detail has been resolved, but when I apply sharpening, the mosiac shaped pattern around the fine detail sharpens up too, and obscures the detail. On areas where there are no fine details, such as out-of-focus areas, these artifacts don’t appear, so I deduce they are not caused by lack of resolution. I wonder if this problem results from the lens out-resolving the 10Mp sensor, and the processor not being able to handle the information when it builds the RAW file. Do you ever see anything like this? It may just be a problem confined to this camera and I’m crossing my fingers that when I get one of the higher resolution cameras the problem will disappear and will find out just what those lenses are capable of 🙂

  • Thank you sir, now all I have to worry about is my technique. ;~)

    I’ve long felt that the camera and lens is a two link chain, and whichever link is the weakest will limit the maximum image quality. Upgrading the camera body will never ever result in lower quality photo’s. Maybe no improvement, but certainly no degradation.

  • Given that the next NEX will probably have an EVF – they are actually really small modules and easy to fit into the body – that is possible. I actually rate the 16mm f/2.8 rather better than, for example, the Minolta 24mm f/2.8 AF in practical terms and FAR better than the MD last generation 49mm thread 24mm. I’m the reverse of the white lens Canon man. I actually would prefer it if my camera was invisible.

  • David, you closed the article with this quote…
    “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…”

    There seems to be a fair amount of concern, and I think confusion, about older lenses being used on a camera with a 24mp sensor. Will you shed some light here? Do we all have to run out and buy new lenses, or will our older primes and zooms continue to give good service when we buy the a77?

    • Ray – I can’t generalise. Some older lenses will outresolve a 24MP APS-C, and some would have done so when new but will not because they are old, used and abused, and have been dropped/repaired/damaged and the buyer will never know. I would trust, for example, any of the Minolta macro lenses, any of the Apo or G series, either of the fast standard 50mms, and a few others. But not many of the early zooms, no matter how much people rave about certain models from 1985-6, are actually all that good compared to modern kit lenses. 28-135mm an exception. Certainly I would not worry about using older lenses, if the sensor simply gets the maximum from the lens (being ‘better’ than the lens) – then you have just got the best out of that lens. Easy!

  • Hi David,
    So, with a couple more E-mount lenses and this 24 MP on the next NEX camera, are you ready to drop the Alpha System for travel photography? 😉

  • Do you need 24 megapixels? Difficult. I have 24, and I’m not using it. But that is because it goes with full frame, needing more and bigger lenses – and since I got my A900 travel weight and cabin baggage size restrictions, along with charges, have all got worse on the low-cost airlines we have always used to reach destinations. We can’t easily afford quick one or two night visits abroad to shoot new stock any more. And when we travel, it’s A55/NEX/A580 and the A580 now seems like a heavy lump! I guess what changed things was the introduction of the Sigma 8-16mm wide zoom and the fisheye and wide adaptors for NEX. With these, I no longer need my 12-24mm Sigma on full frame, or my full frame 16mm fisheye. I thought I *needed* the 900 and its 24MP, but actually I was using it because of the available lens options. Now I can match this with less weight on APS-C 16/14 mehgapixels, I am happier with a more portable system. Also, our main outlet Alamy reduced the file size requirement from 48MB to 24MB (8 megapixels) meaning that crops and adjustments are possible on 14/16MP files without scaling up. Special situation, I know, but that’s the case. I will welcome 24MP on APS-C but may upgrade my entire lens system to match.

  • David, thanks for the clarification. I admit that I too was worried about those 24 MP. Luckily enough I did refrain from complaints, uninformed ones as it turns out, as the net is already too full of noise 😉
    The remaining question however can’t be answered from facts: Do I need those 24 MP, will they slow down my workflow, and most crucial: will I be resistant enough against pixel-peeping 😉

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