# Why 18MP???



## Richard8971 (Jul 23, 2012)

OK guys, I am open minded but with the release of the Canon EOS M we now have yet another APS-C 18MP sensor.

Beginning with the 7D in 2009 (with the exception of the 5D3 and T3) each new Canon camera body released has been 18MP! Now unless I have missed something, is 18MP a "magical" number? Now, mind you, I am not worried about Nikon or higher MP cameras, but I just find it very odd that yet another 18MP sensor has been released.

Thoughts as to why? Did Canon over produce 7D sensors and now they have to get rid of them all?

D


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## neuroanatomist (Jul 23, 2012)

There are two 'flavors' of the 18 MP APS-C sensor. The first was launched in the 7D, and re-used in the T2i/550D, 60D, and T3i/600D. That sensor was modified (or redesigned, if you prefer) for the T4i/650D - multiple clusters of photosites dedicated to phase detect AF directly on the CMOS image sensor were added. In the 650D, they provide phase AF during video shooting. It's that latter, 'new' (sort of) 18 MP sensor that I presume is being used in the EOS M, allowing it to feature phase detect AF without a reflex mirror, instead of only contrast detect AF. 

I'd almost go so far to say that this reworked 18 MP sensor was mainly intended for the new mirrorless body (since fast AF is desirable), and also used in the T4i (although the dSLR launched first).


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## Richard8971 (Jul 23, 2012)

neuroanatomist said:


> There are two 'flavors' of the 18 MP APS-C sensor. The first was launched in the 7D, and re-used in the T2i/550D, 60D, and T3i/600D. That sensor was modified (or redesigned, if you prefer) for the T4i/650D - multiple clusters of photosites dedicated to phase detect AF directly on the CMOS image sensor were added. In the 650D, they provide phase AF during video shooting. It's that latter, 'new' (sort of) 18 MP sensor that I presume is being used in the EOS M, allowing it to feature phase detect AF without a reflex mirror, instead of only contrast detect AF.
> 
> I'd almost go so far to say that this reworked 18 MP sensor was mainly intended for the new mirrorless body (since fast AF is desirable), and also used in the T4i (although the dSLR launched first).



Yes, I got all of that. But WHY 18MP? Why not 24MP or 28MP or 32MP for that matter? I am not a believer that more MP is better as I love my XTi and 40D which both have 10MP sensors. Super images from both camera bodies.

I was just curious if anyone had a theory as the the 18MP "wall" that Canon has seemed to hit.

D


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## bdunbar79 (Jul 23, 2012)

One problem that the 1DX "hit" is that in order to fire off that many fps in RAW format, I'd be hard pressed to believe that a file collecting more than 18mp could be snapped off that quickly. That's part of the reason the 1D Mark III and 1D Mark IV were always lower in MP than their 1Ds2 and 1Ds3 relatives. 

Another problem is that the APS-C sensor itself is smaller, so if you try to cram more, you'll get some serious noise. Now, can Canon go larger than 22 mp? Sure. But that has its own problems. The D800 won't even do mRAW or sRAW because the files are so huge there isn't time to downscale in-camera to a smaller RAW file, or you'd be waiting 30 seconds between shots.

This is at least part of the mp issue.


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## funkboy (Jul 23, 2012)

Thanks for the analysis, Neuro. I'm glad that Canon doesn't seem to be following Sony in continuing the MP race...


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## Richard8971 (Jul 23, 2012)

funkboy said:


> Thanks for the analysis, Neuro. I'm glad that Canon doesn't seem to be following Sony in continuing the MP race...



Oh, I couldn't agree more. I truly think that 15 ~ 18MP is more than enough to capture outstanding images and at this point in the DSLR game, less noise as well.  But it just seems odd that all the sensors have been 18MP, not even 19MP or 21MP. (outside the 5D3)

D


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## nightbreath (Jul 23, 2012)

Richard8971 said:


> funkboy said:
> 
> 
> > Thanks for the analysis, Neuro. I'm glad that Canon doesn't seem to be following Sony in continuing the MP race...
> ...



It seems that Canon has developed special algorithms to efficiently work with output from 18 MPx sensor. So there's no need to run additional R'n'D work if everyone is already happy with current number of pixels.


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## TrumpetPower! (Jul 23, 2012)

Eighteen megapickles is really a great size. It gets you 13" x 19" prints at (almost) 300 ppi, which is as big as almost anybody who uses APS-C camera ever prints and is more than enough image resolution for any application you care to name. It also gets you 24" x 36" prints at (almost) 150 ppi, which is bigger than 99 44/10% people with an APS-C camera ever think to print, and that's a higher resolution than your computer monitor. Or, it leaves you plenty of room to crop.

If you think back to the film days, almost nobody would think of printing even 135-format images at those sizes, and yet you can do it with ease with at 18 megapickle APS-C camera -- quite remarkable, really.

So, more would be better right?

Well, not really. The standard 18 megapickle cameras are already a bit of overkill, though by an amount comfortable enough for both room for error and for those who push the medium beyond its intended design limits. You're not going to be able to do all that much more with more megapickles at your disposal, except maybe crop a slightly bit more aggressively when you're shooting at base ISO, or maybe make 17" x 24" prints instead of 13" x 19" prints, maybe. But the tradeoff is larger file sizes, which means fewer shots on the card, and either a slower framerate and smaller buffer or more expensive onboard processing -- as well as slower processing in Lightroom / Photoshop / whatever...plus bigger hard drives, and all the rest.

All that overhead just so that a minuscule fraction of a percent of the userbase can push the camera even farther beyond the limits of sensibility?

What on Earth for?

No, if you're not getting the image quality out of APS-C that you want / need, do what photographers have done since the beginning: move up to a larger format size. And you can do that once and still use (most of) your lenses. And if the twenty-something megapickle full-frame cameras still aren't good enough, there's medium format up to a hundred or so megapickles, and then large format beyond that if you need even more.

But, realistically, damned few people even push the image quality limits of APS-C, only a small percentage push 135, and you probably don't have to take off your shoes to count those who push medium format's limits. Yes, there are absolutely advantages to the larger formats, and, no, you're almost certainly not one of the people who could put those advantages to good use.

Indeed, unless your printer takes ink by the gallon, 18 megapickle APS-C is perfect for you, with all the image quality you'll ever want or need without any of the headaches that come from bigger systems.

Cheers,

b7


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## nightbreath (Jul 23, 2012)

bdunbar79 said:


> The D800 won't even do mRAW or sRAW because the files are so huge there isn't time to downscale in-camera to a smaller RAW file, or you'd be waiting 30 seconds between shots.



I always thought that it's easier to work with smaller images. When Canon save data in a smaller size, they don't downscale, they just read it in another way (it might be reading and combining each color channel information from 4 pixels into 1, don't remember now about the exact process). It may be more complex for Nikon/Sony sensor to work that way due to different sensor design though.


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## simonxu11 (Jul 23, 2012)

funkboy said:


> Thanks for the analysis, Neuro. I'm glad that Canon doesn't seem to be following Sony in continuing the MP race...



They don't even have a sensor better than sony's 16mp, forget about the higher mp sensors.


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## neuroanatomist (Jul 23, 2012)

Richard8971 said:


> I was just curious if anyone had a theory as the the 18MP "wall" that Canon has seemed to hit.



I do not believe that the "wall" is technical - remember the 120 MP APS-H sensor?

Rather, it's marketing- and profit-based. Marketing, because the T4i/650D and EOS M were the first products to be released with the new APS-C sensor, and they're consumer products. It wouldn't do (from Canon's viewpoint) to have higher MP in a lower _consumer_ product (although they've done it in the pro segment). It would not surprise me to see a 7DII or 70D get a higher MP APS-C sensor with the phase AF. Profit, because the more times they can re-use an already-developed component, the less R&D drain on revenue.


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## akiskev (Jul 23, 2012)

TrumpetPower! said:


> Eighteen megapickles is really a great size.


I think one megapickle is more than enough.


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## JEAraman (Jul 23, 2012)

akiskev said:


> TrumpetPower! said:
> 
> 
> > Eighteen megapickles is really a great size.
> ...



Hahahaah,, Nice one ;D


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## Mt Spokane Photography (Jul 23, 2012)

The design of a camera involves a series of tradeoffs, and when thought out, it might even include some external effects like computer processing power and speed.
A higher MP on a sensor will slow the write speed and reduce FPS, to gain the resolution, it may need a more expensive lens. There are a ton of thinngs that trade off.
Its pretty obvious that Canon feels that the tradeoff favors 18mp on a APS-C body, and using the same sensor on the T4i and mirrorless makes financial sense.
There is also a marketing trade off. Marketers know that many people see more MP as being like more horsepower in a car, and will always want more MP. You can't please everyone, so its always a compromise.


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## AvTvM (Jul 23, 2012)

Richard8971 said:


> But WHY 18MP? Why not 24MP or 28MP or 32MP for that matter?



Because 18MP on an APS-C sensor are just perfect! As simple as that. f/5.6 is peak, f/8 fully useable, diffraction really only sets in big time from f/11 onwards. 18 MP is one of the few decisions by Canon I am truly happy with!

I hope for many more generatiuons of 18 MP APS-C sensors, each one with +1.5 EV danymic range from ISO 100 all the way to ISO 6400.


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## rpt (Jul 24, 2012)

Why 18? Well, apparently the folks at Canon take the Boss seriously. "18 till I die"...

Makes sense to me. I have been 18 for over 3 decades ;D


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## Richard8971 (Jul 24, 2012)

akiskev said:


> TrumpetPower! said:
> 
> 
> > Eighteen megapickles is really a great size.
> ...





rpt said:


> Why 18? Well, apparently the folks at Canon take the Boss seriously. "18 till I die"...
> 
> Makes sense to me. I have been 18 for over 3 decades ;D



OK guys, I don't care who you are, THAT's funny!!! 

What you said makes sense. I can understand more why 18MP has been Canon's choice of sensor size.

D


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## risc32 (Jul 28, 2012)

well, i'm sure all they really care about is moving product. but yeah.


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