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Comment by klodolph | Hacker News Reader

1. Noise increases as pixel size increases. So you can't just make the pixels bigger.

2. The 5 megapixel camera on an iPhone 4 is pretty amazing. I wouldn't call it a waste of resources.

3. Displacing MF from high-end camera manufacturers requires tiny pixels. You can shoot pictures for e.g. magazines on a $2,000 D600 today, but in 2003 you would have needed at least $4,000 MF camera plus a $10,000+ scanner. Yes, this is just a niche of the photography market, but it's an important, high-profile niche.

In my mind, the quality-conscious consumers were taken by digital at 6 MP, and the studios were taken by digital at 24 MP. There are a few morons around with more money than smarts who will buy crappy cameras because the numbers on the box are higher, but it's clear to me that they're not driving the market right now.

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It is simply not true that noise increases as pixel size increases. The exact opposite is widely known to be true. See this page, for example: http://firmitas.org/Sensor.html

I'm not a CCD engineer, but I suspect you're both right.

Photon shot noise increases like the square root of the area of the pixel, but the signal will increase like the area.

In that case, the important quantity ( Signal/Noise ) improves like the square root of the area of each pixel.

If readout isn't shot-noise limited, then the payoff for a larger sensor could be as large as the ratio of the areas between old and new.

I was actually just paraphrasing the linked page from Canon:

> In addition, the sensor's pixels and readout circuitry employ new technologies that reduce noise, which tends to increase as pixel size increases.

The linked page is pretty sketchy, it mentions lenses but not optics. Optical resolution will be limited regardless of whether the lenses are perfectly polished. It's hardly irrelevant too, with modern optical resolution close to sensor resolution. The article makes assertions but no citations or measurements. Worthless junk.

Well they're describing the sensor, not optics, so that part is forgivable.

Also, they're describing a 35mm sensor. This thing will work with existing 35mm film optics, and (apart from physical properties) that's a big part of why the sensor size is interesting.

Would be nice if there were more technical details, but I guess that's press releases for you.

On top of what others have said, let's not forget thermal noise - I can't find it right now but I remember a beercooler-as-SLR-cooler hack someone used to near-freeze his camera, making his long exposure astronomy pictures much less noisy. Also, I've heard that because of this it can be better to shoot a lot of medium-exposure pictures in burst mode and additional-blend them afterwards than having the sensor capture for, say, ten minutes non-stop.

So, since the heatigng up in turn depends largely on current running through the sensor: how does that scale with larger/smaller pixels?

I think the gp might be talking about quantization noise...

> Noise increases as pixel size increases.

No, it's the reverse -- relative to photon collection efficiency, noise decreases as pixel size increases. For a given pixel size, you have various noise sources, and you have the photon collection efficiency of the sensor. As the sensor becomes larger, the photon collection efficiency increases much faster than the noise does.

http://firmitas.org/Sensor.html

Quote: "The size of a pixel directly impacts how much noise an image will have in low light, and in some cases even in daylight. The bigger the pixel is, the lower the noise because more photons can reach a bigger pixel sensor."

>1. Noise increases as pixel size increases. So you can't just make the pixels bigger.

No, it does not. It also depends on the sensor technology. Newer APS-C 16 and 20 mp cameras have less noise than 3mp APS-C cameras of 10 years ago, even without applying in-camera noise reduction.

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