Pixel Size

[MarkBarbieri]

I'd like to see the camera makers introduce a new metric called "pixel size" and start promoting that as hard as they do megapixels. That would help stop this suicidal war into more and crappier pixels on sensors.

You can get an approximation of the pixel size by dividing the number of pixels into the size of the sensor. That doesn't take into account the gap between pixels (which differs on different sensors). Even if you do know the pixel size, that doesn't tell you much about the quality of the A/D converter, the eletrical noise levels inside the camera, the quality of the microlenses, or a number of relevant factors. Still, I think it's a better quick measurement of IQ than megapixels, especially for 6mp and above cameras.

Here's how some of the current crop of cameras shape up using a thousands of pixels per sq mm measure. All other things being equal, a lower number should mean that each pixel produces a more accurate and lower noise reading. Things aren't always equal and pixel quality is only one of many factors in image quality. Still, by pushing pixel size as a metric, it would make manufacturers think twice about shoving 12 million pixels on a sensor the size of a pin head. It might also spark a move towards larger sensors in consumer cameras.

8 - Canon 1D (original 4mp version)
14 - Nikon D3
16 - Pentax K10D/K100D
24 - Canon 1DsM3
27 - Nikon D40x
31 - Canon D40/Rebel XTi
31 - Canon Rebel XTi
33 - Nikon D300
34 - Fuji S5 Pro
44 - Olympus E-410
56 - Fuji Finepix S6500fd
111 - Canon G9
241 - Canon S3
321 - Canon S5
325 - Sony DSC-H9

As you can tell by the inclusion of the almost antediluvian 4mp Canon 1D, comparisons of different models over time can be dicey. They've learned a lot about making better sensors since the olden days of digital cameras.

 

[boBQuincy]

In a word (two words), forget it!

You and I and some others would use this information but we already know where to find it anyway. Marketing wants one convenient number to sell with, and pixels are it.
In vehicles it's horsepower (or mpg), which tells about as much about performance (or real world fuel economy) as pixels does for cameras, but it's something easy the customer can remember and compare.

As long as the first question most customers asks is "how many pixels does it have?" the pixel count will continue to go up and image quality will be secondary, if even that much. As for us, we will always be forced to look up the sensor size and pixel count to get some idea of image quality.

 

[Groucho]

That's been one of my rants for a while once I get started complaining about sensor size.

However, your numbers have at least one or two errors - specifically, the Pentax K10D is a 10mp camera and the K100D is a 6mp camera, both with the same sensor size (either exactly or within a couple mm.) The K10D should be about the same as the D40x, A100, and D80 as they all use a Sony 10mp sensor which is the same in each, I believe. Similarly, the K100D would be the same as the D40.

And I didn't know that Canon made a D40. One other thought, the Fuji S6500fd is the same as the S6000fd IIRC, it's just the name that they use in Europe.

I'd like to see some solid improvements in quality being made - which it sounds like they're slowing getting towards. Certainly, Sony's 10mp APS-sensor is generally not much worse than their 6mp in terms of noise, not bad for the big leap in pixels. And the new 12mp ones are apparently even better. The problem with PnSs is that I think they're increasing pixel counts faster than quality can keep up, especially as they've been woefully underperforming for a long time.

 

[seashoreCM]

How are the test shots in camera review articles?

Test patterns that show converging lines for resolution tests and color patches for noise tests should give a good idea of the camera's performance taking the lens quality and sensor quality and pixel size and all those factors into account all at once.

When you look at test shots on line, you may need to adjust your browser so the picture is at full size and you scroll (or pan) to see everything. If you let the browser downsize the picture to fit your screen, that wipes out detail and nullifies the benefits of seeing the test shot. On Internet Explorer you need to uncheck (disable) automatic image resizing in the internet options advanced menu (exact menu may differ with internet explorer version).

Here's an example using a 6 megapixel point-and-shoot (registration on that site needed):
http://forum.digitalcamerareview.com/showthread.php?t=1097