FF vs. APS-C - Aperature Behaviour

[Daniel Browning]

Beware that the Canon CMOS "White Paper" is hardly a white paper at all -- more like a marketing fluff piece. While it does have quite a bit of good information, Canon also mixes in enough misinformation and bald-faced lies (oops, I mean "marketing") that I can

[HDNitehawk]

Beware that the Canon CMOS "White Paper" is hardly a white paper at all -- more like a marketing fluff piece. While it does have quite a bit of good information, Canon also mixes in enough misinformation and bald-faced lies (oops, I mean "marketing") that I can't recommend it.

I would think it is obvious it is marketing. It is an old document, and was produced to promote the CMOS sensors.


I guess I would have to ask, where are we being mislead?

[Jon Ruyle]

#3 matters more than 1 and 2. We know that 5D II will handle noise better.

I agree that #1 is irrelevant to the discussion. Talk of pixel density only adds to the confusion.


Tecnhology, however, can only take you so far. Sensors are less than 100% sensitive (ie, they register fewer than 100% of all photons), but the day isn't far off when sensors will be close enough to 100% sensitive that the only real parameter of the three will be sensor size. In the end, it is really effective f number that determines how fast one can expose (or, with a given f number, sensor size is what matters).

[dsiegel5151]

I have no horse in this debate here, but I remember reading this from dpreview when the 50D came out (read below)... I remember thinking to myself that a camera like the 7D would never come out, because the pixel race was obviously over. Now, I don't think anyone would argue that the 7D not only resolves more detail than the 40D, but also has better high ISO performance as well (read 7D review following 50D). In conclusion, I agree with HDNitehawk. Technology can even the playing field even if pixel density is greater.


50D review: "Let's have a look at the really important stuff then: Image quality. Below ISO 1600 image output is clean with well balanced contrast and colors and as you would expect from a DSLR with a 15 megapixel sensor the 50D delivers a fair amount of detail. Having said that, in terms of per-pixel sharpness the 50D cannot quite keep up with the better 10 or 12 megapixel APS-C DSLRs in the market. At higher sensitivities the smaller photosites are clearly producing more noise (as shown from our RAW comparisons) and so Canon is having to apply more noise reduction to keep to acceptable noise levels, this of course means a loss of detail from ISO 1600 upwards.


It appears that Canon has reached the limit of what is sensible, in terms of megapixels on an APS-C sensor. At a pixel density of 4.5 MP/cm² (40D: 3.1 MP/cm², 1Ds MkIII: 2.4 MP/cm&sup2 the lens becomes the limiting factor. Even the sharpest primes at optimal apertures cannot (at least away from the center of the frame) satisfy the 15.1 megapixel sensors hunger for resolution. Considering the disadvantages that come with higher pixel densities such as diffraction issues, increased sensitivity towards camera shake, reduced dynamic range, reduced high ISO performance and the need to store, move and process larger amounts of data, one could be forgiven for coming to the conclusion that at this point the megapixel race should probably stop. One consequence of this is that the 50% increase in pixel count over the 40D results in only a marginal amount of extra detail."


7D review: "Despite the highest nominal resolution of all APS-C DSLRs and therefore a very small pixel-pitch the EOS 7D performs very well in low light situations and manages to maintain a good balance between image detail and noise reduction up to very high sensitivities. It's visibly better than the EOS 50D and as good as it gets in the APS-C class (if you prefer the 7D or Nikon D300S in this respect is probably a matter of taste). If you require significantly better high ISO performance than the EOS 7D can provide, your only option is to move into the full-frame segment."

[Daniel Browning]

I don

[Daniel Browning]

dsiegel5151, quite a difference between their 50D and 7D reviews, huh? [] More reason to distrust what you read on DPR. Let me pick apart of a few of their summary points:

<span>the 50D cannot quite keep up with the better 10 or 12 megapixel APS-C DSLRs in the market. Athigher sensitivities the smaller photosites are clearly producing more noise (as shown from our RAW comparisons)

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This is doubly incorrect. First, their "RAW" comparisons are badly flawed and not even raw at all. Second, even from their flawed comparisons it's possible to see that for similar levels of detail the 50D has the same noise level as the 40D -- not worse.

It appears that Canon has reached the limit of what is sensible, in terms of megapixels

Several years later, we now have Nikon's D7000, which is so far ahead of anything Canon has ever made that it's not even funny, especiallywhen it comes to base amplification read noise. And there are 2-micron digicam pixels that even better than that (but haven't been made into APC-S yet).

At a pixel density of 4.5 MP/cm&sup2; (40D: 3.1 MP/cm&sup2;, 1Ds MkIII: 2.4 MP/cm&sup2 the lens becomes the limiting factor.

DPR's silly made-up terms and measurements annoy me a lot I prefer to use industry standard terms likes "pixel pitch" and measurements such as microns for pixel diameter. It's not very smart that they think it is a bad thing for the lens to be the limiting factor. Are lenses some sort of cheap throw-away accessory that is easy to improve, and that's why we never want our sensor to be limited by them? I take the opposite view: our lenses are the most expensive and important part of the system, and they are more expensive to improve than the sensor, so we never want our lenses to be limited by our sensor. So if your sensor has such poor resolution that it can't see the lens flaws, that is suboptimal.

Even the sharpest primes at optimal apertures cannot (at least away from the center of the frame) satisfy the 15.1 megapixel sensors hunger for resolution.

Nonsense. The cheapest zoom at the worst aperture in the very corner of the frame still has more than 10% MTF necessary to achieve line separation on a 15.1 MP sensor. That means it's still necessary to have a contrast-reducing optical filter to limit aliasing artifacts.

Considering the disadvantages that come with higher pixel densities such as diffraction issues, increased sensitivity towards camera shake, reduced dynamic range, reduced high ISO performance and the need to store, move and process larger amounts of data, one could be forgiven for coming to the conclusion that at this point the megapixel race should probably stop

What a load of BS (Bad Science). []



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[dsiegel5151]

Yeah, it

[Fast Glass]

Thats like saying you shouldn't scan a slide more that an XXXX about of resolution because your limited by your slide in the first place. What a load of Bad Science.[]


Cheers,


John.