Does it make sense? An $1800 Full frame DSLR from Canon

[jblaschke]

<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span style="font-size: small;"]<span style="font-family: Times New Roman;"]From an engineering point I would say that the 50D is a step to far, a 1.6X sensor at 15mp is going to give problems that are not worth the extra resolution.<span> I think (hope) that the next mid range body 60D??? would have to have a larger sensor.<span> One would hope for full frame but suspect that a 1.3x sensor would be canons preferred option if forced down that route, but I think that all of the manufactures will try desperately to keep the 1.6 and 1.5X sensors.<span> So a 1.3x or FF sensor at &pound;1200 (proper money) may not be too far away&hellip; <span>What is really needed now is a totally new type of sensor.<span>
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Never going to happen. Canon won't change sensor size on the crop-body cameras any time soon. They're not going to orphan the EF-S lenses and the cash inflow those generate. That's the entry-level to semi-pro market, and they've invested a lot of time and effort into convincing the public this is going to remain viable for a long time. Dumping the platform now would revisit the FD rancor of years past. The 5D II is too popular, and the Mark Is are commanding a comparable price to the 50D on the secondary market. I suspect Canon's happy with that.


I could see Canon expanding the 1.3x with a line of mid-pro cameras, but in all honesty, I suspect that chip is an evolutionary dead end. I'd expect Canon to develop a "new" 1.6 APS-C chip that's able to sidestep some of the current limitations while retaining the current size. Remember, Canon was criticized for cramming too many megapixels onto the D60 chip way back when, and they've long since worked around those issues.

[wolf]

You have to realize that sensor size and not pixels is at the root
of high camera cost for FF. The silicon cost wouldn't change much if
you had less pixels (you'd have a slightly larger yield with lower MP
sensors, which would reduce the cost).


If you have larger pixels (i.e. less MP for the same area) you're
going to have lower noise, which is why the original 5D was so good
(compared to the crop sensors at the time) and why the Nikon 700 is
less noisy at high ISOs (noise processing also helps). Less MP also
reduces lens aberrations, which is why people say the 40D has better
picture quality than the 50D.


The only way to reduce the price of FF cameras is to sell more of
them, then the cost per sensor die is reduced (the reason why Pentium
chips can be sold for the prices they do since they're produced in
hundreds of thousands).

[Daniel Browning]

Daniel: Wow! You know a lot of info. Do you work for Canon? :-) Sorry about my ignorance, but what is a semiconductor mask (reticle)? Thanks!

Thanks, Johan. Photography is just my hobby, but I enjoy getting deep into it.

The reticle is the quartz "master" image of the sensor. A laser is shined through the reticle, focused onto the much smaller silicon wafer. For further reading, I suggest the following "white paper" from Canon:


http://forums.dpreview.com/forums/read.asp?forum=1000&amp;message=30412083



http://www.pbase.com/jkurkjia/50d_vs_40d_resolution_and_noise

I think (hope) that the next mid range body [60D?] would have to have a larger sensor.

It does not "have to have" a larger sensor at all. Resolution can and will continue to improve in APS-C cameras. A larger size would not only increase cost greatly, but would not benefit the use of EF-S lenses.

A different sensor size would be a completely different product line.

One would hope for full frame

There is already a full frame option: the 5D series.

but suspect that a 1.3x sensor would be canons preferred option if forced down that route

It's possible that Canon could remove some features from the 1D 1.3X series, but the increased sensor size alone is still going to make them more expensive than APS-C.

Larger sensors are not going to get cheaper because you want it. Nor because you believe Canon reached some sort of "limit" in APS-C. Even if they had reached any kind of limit, that's not going to make larger sensors any cheaper.

but I think that all of the manufactures will try desperately to keep the 1.6 and 1.5X sensors.

Your position is indefensible.

The cropped lenses from any manufacturer rate along side betamax, hd-dvd, and French cars, just another con to get people to buy and then be forced to buy again!

If you're serious, then I think you're incorrect. If you're trying to be funny, then I fail to see the humor.

you'd have a slightly larger yield with lower MP
sensors, which would reduce the cost

Interesting. I haven't heard that before, but I do know that dead pixels on higher MP sensors affect the total image much less than the same number of dead pixels on a lower MP sensor.

If you have larger pixels (i.e. less MP for the same area) you're going to have lower noise, which is why the original 5D was so good (compared to the crop sensors at the time)

I disagree. If you have a larger *sensor*, you're going to have lower noise: pixel size is almost irrelevent. A digicam with a teensy, tiny sensor will never have less noise than a full frame senosr. Even if the digicam has large 200-square-micron pixels and the full frame sensor has tiny 16 um^2 pixels, the DSLR will still have less noise.

The 5D proves my point. If you compare "for the same area", as you said, then you take away the advantage of the large sensor size, and it's plainly worse than even the 20D. For example, for a given fixed exposure (f-number and shutter speed), the 20D collects 0.76 photoelectrons per ADU per square micron, whereas the 5D only records 0.61 e-/ADU/um^2. The smaller 20D is 20% more efficient. The difference in read noise is even more disparate.

So the "large pixels" of the 5D are plainly worse than the "small pixels" of the 20D. It's only the *sensor size* that makes the 5D better, not the larger pixels. Another example is the 1Ds3, which has smaller pixels than the 5D, but much higher quality (sensitivity and read noise).

And why the Nikon 700 is less noisy at high ISOs.

That's true. However, the Sony-built D3X has much less noise at low ISO, and far more dynamic range than the D700, despite much smaller pixels.

Less MP also reduces lens aberrations

I disagree. The aberrations are there no matter what size pixel you have. Smaller pixels just allow the photographer to see them if he so desires, whereas large pixels are so blurry that they can't resolve the aberrations.

Choosing to use large pixels for the purpose of "reducing lens aberrations" is sticking one's head in the sand. They're still there, you just can't see them. One may still stick their head in the sand with a 50D, just resize the image down to the spatial resolution of the 40D.

The wrong question is "what resolution is low enough and blurry enough to hide all the optical imperfections in my lens?".

The right question is "what resolution is high enough and detailed enough to to extract every last drop of information from my lens?".

I already know that much of my glass has useful information at extremely high resolutions, because I've used them with teleconverters. I'm looking forward to 200 MP, 500 MP, and 1 GP sensors in the future.

[wolf]

You're right in the sense that lower MP hide lens aberrations which is what I meant by "reducing lens aberrations".


It's not just pixel size that reduces noise, it's the on-chip (or software) noise reduction algorithms. If you took the raw data (without noise reduction being applied) of two chips (with same physical size), the one with larger pixels will appear to be less noisy.


There is always a tradeoff when changing a single parameter. Smaller pixels (higher MP count): bigger enlargements but more noise at high ISOs. More noise reduction: less noise but you lose detail.


When comparing sensors of the same size, like the Nikon D700 and Sony A900, the one with less pixels will typically appear less noisy (without considering noise reduction). But there are always limits and if you push the number of MPs past a certain limit you loose the benefit and other factors come into play such as lens aberrations and noise issues.

[Daniel Browning]

It's not just pixel size that reduces noise, it's the on-chip (or software) noise reduction algorithms.

I'm aware of when and where noise reduction occurs.

If you took the raw data (without noise reduction being applied) of two chips (with same physical size), the one with larger pixels will appear to be less noisy.

I disagree.

There is always a tradeoff when changing a single parameter.

Yes, there is always a trade off, but noise is not one of them. The trade off for smaller pixels is stronger in-camera processing power, more storage space, slower demosiac and post processsing, etc.

Smaller pixels (higher MP count): bigger enlargements but more noise at
high ISOs.

I think that is a common misconception. For a given sensor size the "noise per detail" (i.e. noise power per spatial frequency) stays the same no matter what the pixel size. The only difference is that smaller pixels allow one to use higher spatial frequencies. This is illustrated in the link I provded above for the 50D/40D.


http://luminous-landscape.com/forum/index.php?showtopic=29801&amp;view=findpost&amp;p= 241562


When you compare them at different spatial frequencies (detail) by using 100% crop, the 50D appears to have more noise. But when you compare them at the same spatial frequency (amount of detail) by resampling both to the same resolution, it becomes clear that their noise is in fact the same.

[ShutterbugJohan]

Daniel Browning said:


"Interesting. I haven't heard that before, but I do know that dead
pixels on higher MP sensors affect the total image much less than the
same number of dead pixels on a lower MP sensor."


Thanks for the responce, Daniel. That White Paper is very informative. What is the purpose of dead pixels? I believe that my Canon 10D has 6.5MP, but is only uses 6.3MP. Thanks.


--Johan

[Daniel Browning]

What is the purpose of dead pixels?

Every sensor has a number of dead pixels and/or hot pixels, where they are full brightness even in the absence of light. They can be caused by impurities in the silicon. Most of them are "mapped out" at the factory. Mapped-out pixels are interpolated from the surrounding pixels. New ones often develop after the camera is shipped, resulting is a surprised customer, until the user learns how to map out the bad pixels themselves, like so:


http://community.the-digital-picture.com/forums/t/673.aspx

[Jon Ruyle]

I disagree. If you have a larger *sensor*, you're going to have lower noise: pixel size is almost irrelevent.

I would have guessed read noise would be larger when you have more pixles (so high pixel density would hurt snr). Are you saying that isn't true? Or that it is true and isn't a significant factor?

[Colin]

He's saying that if you look at signal to noise per pixel, it is true. However, if you look at noise per sensor area,the pixel size is irrelevant. If you look at noise per image area, the larger sensor willl have an advantage regardless of the pixel size.


At least, that's what I retained from a previous related post []


quick example. Half the pixel dimension, 4 small pixels for every 1 big pixel. 1 Big pixel has 4 times the signal to noise as 1 small pixel, because it's got 4 times the signal (4 times as much light). HOWEVER, 4 small pixels, same area, have the same signal to noise ratio as the 1 big pixel, because they get the SAME amount of light, total. If yousum the output of the four small pixels, and average, the signal sums, and the noise cancels out. You lose detail, you increase signal to noise. What more pixels allows you to do is filter more selectively, after the fact, as opposed to filtering mechanically by larger pixel size.

[Daniel Browning]

If yousum the output of the four small pixels, and average, the signal sums, and the noise cancels out. You lose detail, you increase signal to noise. What more pixels allows you to do is filter more selectively, after the fact, as opposed to filtering mechanically by larger pixel size.

Excellent summarization, Colin.


For an example, take a comparison between pixel sizes of 4 microns and 2 microns:

• If the 2um pixel has read noise that is twice as bad, then the final image has the same read noise.
• If the 2um pixel has read noise that is the same, then the final image has much less read noise.
• If the 2um pixel has more than twice as much read noise, then the final image has more read noise.

So smaller pixels can be noisier per pixel (by an amount equal to the square root of the difference in size) to achieve the same amount of noise as larger pixels. My position is that, all other things being equal, smaller pixels do tend to be just about that much noisier, and so the final image is just about the same.