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Why is 4/3 "stuck" to 16mp when Sony 1" sensor is 20mp?

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Elaka Farmor

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Why is 4/3 "stuck" to 16mp? The argument that it is not possible to get more real resolution falls flat: Sonys´1" sensor is 20mp and shows a great deal of resolution. Only the lens which cannot make the sharpness through out in the corners (RX100)
 
Sensor resolution is a tradeoff against a number of things. One of those is readout speed. The 4/3s cameras have much better video than anything Sony has released to date. Part of that is how data from the whole sensor is read out and combined (do you sample 1 in 10 pixels? Do you read all the pixels and combine? If so, how?). This also feeds into PDAF autofocus speed and shooting speed. Shooting speed, in particular, has elements in control of the camera (sensor readout and buffer) and out-of-control (card speed).

It trades off against low-light. As you increase resolution, low-light performance falls off ever-so-slightly. As you continue to increase, it falls off more rapidly. Once you go beyond some point, it falls like a rock. Where that point is is a question of the size of support electronics needed for each pixel. Part of that is technology -- and Sony is probably technologically ahead here -- and part of that is what functionality you want.

Another relatively fundamental tradeoff is dynamic range. We can quibble about this one, but generally bigger pixels have more dynamic range.

So it's a whole pile of engineering tradeoffs. My guess is part of it is that Sony has better tech, but a bigger part of it is that Sony targets naive consumers who look at megapixels, and so makes engineering tradeoffs to really push that spec.
 
I still believe they didn't manage to make more resolution sensor with the same amount of noise and other problems. Also diffraction and other issues comes faster with higher resolution, there is processing power issue, power consumption etc... So manufacturers decided to keep some qualities in sacrifice of high resolution... This is my not so wild guess. It would be nice to have at least one higher res model in camera line of each company, but it's propably not worth for them....
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Why does he do it?
 
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The two top professional sports cameras in the market are 16MP and 18MP and for exactly the reasons already mentioned by the other posters.

Not everybody needs 36MP.

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Chris R
 
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Alphoid said:
The 4/3s cameras have much better video than anything Sony has released to date.
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Do they? I was close to buy an E-PL5, but it has only 30fps at 1080p. I´m impressed about the video quality that RX100 does (1080p 60fps) and what I heard about RX10 it´s even better.
 
The theoretical best linear difference in resolution between 20Mp and 16Mp is just 12%. Just 1/8 th more resolution.

That's not much at all.

If you think you're going to crop more out of 20Mp than 16Mp then what you're actually going to be able to crop is that 12% extra - one eighth.

So these headline grabbing 20Mp numbers are essentially useless.

And if you display these images on a HD TV you're using 1Mp. A top quality 8x10 print uses just 7Mp. A wall filling print from 7Mp will look great.

You can convince yourself they give you a load more resolution if you like, but the reality is that they could not possibly add more than 1/8th extra.

Now if you want to be impressed by a sensor, be impressed by the E-PL5 and E-PM2 sensors. They're only a small percentage off the high ISO performance of the best APS-C sensors. They're punching way above their weight. That's a real difference I can translate into more detail and faster shutter speeds.
 
ryansholl said:
1/8?
You have failed at the maths.
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No, he is correct. A 25% increase in the total number of pixels only gives a 12% increase in resolution in each direction, width and height.

It is a common error by beginners to think that doubling the number of pixels doubles the size of print that you can make. It doesn't, it only increase the size by sq root of 2.

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Chris R
 
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It´s more about rhetorics. Of course it doubles SIZE. But here comes question what do you mean by size? If you have 16Mpx image at 10x15 inches, you can make the same dpi image 20x15 with 32Mpx sensor. That sounds like double size to me. If it sounds like 20x30 to you, it can be right, but it´s certainly different meter for size. But as most of human senses are not linear, I agree that double the size is more likely to be 20x30 for your eyes, so that few megapixels increase is not worth all that hassle and problems.

I hope Canon manages to use their dual pixel sensors as single pixel (double the resolution). It would be just fun to have this option for more resolution when needed.
 
I believe that in a future generation of 4/3 camera, we will see that 16mp sensor increased as technology permits. I also believe that the resolution on the Fuji APC sensors will also be increased again as technology advances. It wasn't that many years ago when a top of line FF sensor had only 6-8 mp.
 
crashpc said:
I still believe they didn't manage to make more resolution sensor with the same amount of noise and other problems. Also diffraction and other issues comes faster with higher resolution, there is processing power issue, power consumption etc... So manufacturers decided to keep some qualities in sacrifice of high resolution... This is my not so wild guess. It would be nice to have at least one higher res model in camera line of each company, but it's propably not worth for them....
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Why does he do it?
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More resolution in a sensor the same size will mean diffraction impacts sharpness at larger apertures.

Basically when you put more resolution into a smaller sensor you need a faster lens to get the best of that sensor. Whats more unlike larger sensor ultra fast lenses that give very shallow DOF meaning boarder/corner performance isn't needed the lens for a smaller sensor needs to be giving across the frame performance even when shooting at large apertures.

Most compacts actually haven't had AA filters for years not because manufactures were willing to risk aliasing but because they were so diffraction limited that the blur caused had the same effect as an AA filter.

My guess is this means that the RX100 beyond the sensor noise issues likely has trouble exploiting its true resolution because your stuck between either shooting at large apertures with less than great boarder performance or being heavily diffraction limited, especially at the long end.
 
As others have said doubling the number of pixels at best will only increase linear resolution ( in any direction on the 2D film plan ) by a factor of the square root of 2.

But that assumes that the lens and aperture are capable of delivering that extra resolution.

The assumption being made by the OP is that the lenses really resolves that level of detail, and that's not a given. It would indeed by an impressive lens if it could do that, as few DSLR primes could do it.
 
Okay. Again bad rhetorics and terms used. Of course diffraction has nothing to do with the sensor resolution, but one is diffraction limited at sensor resolution(size of each pixel). So no matter how I write it, the truth is that diffraction affects higher resolution sensors more (even when amount of that effect is the same...)

MoreorLess

I get that, and I agree...

darklamp

Twice the (absolute) resolution, twice as big sheet of paper. It really depends on method you use to explain things. I hope we both get each others method, so there is no need to repeat ones version again and again. The lens is mean factor here. Smaller the pixel, less resolution you get. So after next generation of lenses and sensors, we´ll rely on strict laws of physics instead of technology untill we bend it or we make very different device avoiding current probs. It´s funny to watch that we are hitting the wall on many frontlines.
 
crashpc said:
Okay. Again bad rhetorics and terms used. Of course diffraction has nothing to do with the sensor resolution, but one is diffraction limited at sensor resolution(size of each pixel). So no matter how I write it, the truth is that diffraction affects higher resolution sensors more (even when amount of that effect is the same...)

MoreorLess

I get that, and I agree...

darklamp

Twice the (absolute) resolution, twice as big sheet of paper. It really depends on method you use to explain things. I hope we both get each others method, so there is no need to repeat ones version again and again. The lens is mean factor here. Smaller the pixel, less resolution you get. So after next generation of lenses and sensors, we´ll rely on strict laws of physics instead of technology untill we bend it or we make very different device avoiding current probs. It´s funny to watch that we are hitting the wall on many frontlines.

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Why does he do it?
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To me the RX10 actually shows you the problem with high resolution very small sensors, not only do you need the large fast lens to try and offer similar low light and shallow DOF performance closer to larger sensors, you also need it to avoid difftraction.

A lot of RX100 reviews I'v seen seem to make the mistake of believing that because overall sharpness peaks at say F/5.6 the lens isn't being diffraction limited before this point. The reality is I'd guess that it is, its just that the lower performance of the lens at larger apertures is having a worse effect than the difftraction and you've got not way to fully exploit the sensors potential.
 
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Elaka Farmor said:
Alphoid said:
The 4/3s cameras have much better video than anything Sony has released to date.
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Do they? I was close to buy an E-PL5, but it has only 30fps at 1080p. I´m impressed about the video quality that RX100 does (1080p 60fps) and what I heard about RX10 it´s even better.
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There are two types of specs. Paper specs and real specs. The actual resolution of a Panasonic GH2 will blow away anything I've seen from Sony -- which includes their flagship APS, the A77 -- but I have not seen the RX10. The RX10 has some promising reviews. On the other hand, Panasonic has since released the GH3 and GH4. The GH4, in particular, is supposed to be a very big step forward. A lot of that tech bubbles down to the lower-end Panasonics.

I have not looked at the actual resolution of video off of the RX100, but that's because as a serious video camera, it is a joke. It's missing basic features like audio levels. It's my favorite camera right now, mind you, but I would not treat as a serious video contender.

I have not evaluated video quality from Olympus cameras in any rigorous way -- again, for serious video I turn to Panasonic -- but I've used one for B-roll, and it seemed usable.

Indeed, if you take GH2 video, downsample to 720, upsample back up to 1080, it will look very similar to A77 output.
 
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Exactly. Totally agree with you on that. This will happen more and more as we increase resolution of bigger sensor. There will be some (maybe dull) peak with two downhills - one from Diffraction, second for lens construction (size, DoF etc) on every camera later in next generations.
 
crashpc said:
Okay. Again bad rhetorics and terms used. Of course diffraction has nothing to do with the sensor resolution, but one is diffraction limited at sensor resolution(size of each pixel). So no matter how I write it, the truth is that diffraction affects higher resolution sensors more (even when amount of that effect is the same...)
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I think 'diffract affects higher resolution sensor more' is a really bad way of putting it - people read it and think you get bigger diffraction effects from a high res sensor, which of course is a nonsense, the size of the diffraction effect doesn't depend on the pixel count of the sensor at all. Ideally, the sensor should never be the cause of the resolution limit, so the ideal camera would be diffraction limited at all apertures.
 
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