What products would you launch if you were Canon?

Started Sep 15, 2010 | Discussions thread
fyngyrz Senior Member • Posts: 1,606
Re: I'd launch a low-light line

Split answer, STUPID 6000 char limit

Daniel Lee Taylor wrote:

fyngyrz wrote:

...something with very large, quiet sensels, about 5mp in APS-C or perhaps 12mp in FF.

This would make no difference. Total sensor surface area is the primary factor in high ISO

No, it isn't. This is one of the many tech-myths that float around here, pushed by some very confused people. Noise is all about the size of a sensel, everything else being equal. If you take an 8mp crop of a 5DmkII sensor, the noise per pixel in the crop will be exactly the same as the noise per pixel in that region before you cropped it. Cropping doesn't change pixels. But the size has changed (to APS-C, coincidentally.) So, continuing, if you put that 8mp slice in a APSC camera, you'd have the center of the 5DmkII image, same noise per pixel and per image noise for the 5DmkII's cropped area - absolutely no way to tell them apart - the original crop and the smaller sensor. This demonstrates conclusively that noise follows pixel size, NOT image size.

What a larger sensor gets you, though, is the opportunity to put a lot of larger pixels in there. And that's what we see with the 5DmkII. The pixels are MUCH larger, for instance, than the 50Ds, but are of a quite comparable level of technology. And, no surprise, they're quieter.

, followed by technology level. Pixel size is not a significant factor because smaller pixels are magnified less in print, offsetting any losses in per pixel noise.

Not to put too fine a point on it, print is something you do. It's not something I do. Ever. I don't even own a printer. So clearly, print is entirely irrelevant in determining noise.

In fact, noise is quantified by the amount of actual image information as compared to the non-image information in each pixel. Not by printing.

Consequently, the way one reduces noise is to change that ratio. A larger pixel in a given area (like FF) means that there are fewer pixels. This means that the external noise of the read, which is independent of the content of the pixel, is added fewer times. This means there is less of it. Yet there is still the same amount of light collected, so you get the effect of binning: If you have 1/4th the pixels, you'll have 1/2 the noise (sqrt(bin_count)). BUT! Because the external noise is added after the bin, which is done just by a larger pixel, the ratio of image noise to light noise drops. And we want the light noise - it's really a part of what we are imaging. Even so, because we bin 4x the amount, it settles out to a more even representation of what we're looking at.

The down side, of course, is you also get 4x less detail. But I'm ok with that, and you know why? Longer lenses.

If engineers at Canon, Sony, or Nikon could achieve leaps in high ISO with a 5 MP DX sensor, we would already have it.

We do. It's called the Nikon D3(s?), it goes to ISO 102k, it's FF and 12 mp, and it's awesome .

With gapless microlenses the amount of light captured depends entirely on the surface area of the sensor, not the pixel size.

Yes, the amount of light, but not the electronic noise. With gapless microlenses, the size of the pixel is the size of the microlens, that's all. When you have pixels with 4x the area, you also have microlenses that are designed to capture 4x the area, which they do, and so at the high end, you have the same amount of light, and at the low end you have the sum of the original four pixels before the external read noise gets added, so the ratio of external to internal noise drops at the same time that the average light level settles down (because there is 4x the area feeding the single pixel read.)

Lower MP images have some other beneficial side effects, too; they can be processed a lot faster by the camera, leading to potentially higher frame rates;


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