Myth busted: smaller pixels have more noise, less dynamic range, worse diffraction, etc.

[Colin]

Oops,nevermind, was looking at the first page.... []

[mpphoto12]

wow how do u yake pictures of the moon that close and stars? i can get decent with a 70-200 but noth that good.

[Colin]

Oh, wait, moon pictures are okay! That wasn't the first page, but the second... Much different :P


resized to 800x800, whole moon...





100% crop for reference....








Just because it was in the same folder....

[Daniel Browning]

I'm going to try and move a discussion from a different thread to this one (http://community.the-digital-picture.com/forums/t/1886.aspx).

But why did Canon say that larger pixels have better noise?

http://media.the-digital-picture.com/Information/Canon-Full-Frame-CMOS-White-Paper.pdf

For the same reasons that everyone else says it: flawed image analysis and errors in reasoning. (This "white paper" is actually a marketing/sales document, so that's another reason for flaws.)

One of the most common mistakes in image analysis is failing to account for unequal sensor sizes. Sensor size is separate from pixel size. Some assume that the two are always correlated, so that larger sensors have larger pixels, but that is an arbitrary assumption. Sensor size is generally the single most important factor in image sensor performance (as well as other factors such as cost); therefore, it's always necessary to consider its impact on a comparison of pixel size. The most common form of this mistake goes like this:

* Small sensors have smaller pixels than large sensors.
* Small sensors have more noise than large sensors.
* Therefore smaller pixels cause more noise.

The logical error is that correlation is not causation. The reality is that it is not the small pixels that cause the noise, but small overall sensor size.

If pixel size (not sensor size) was really the causal link, then it would be possible for a digicam-sized sensor (5.6x4.15mm) with super-large pixels (0.048 MP) to have superior performance to a 56x41.5mm sensor with super-tiny pixels (48 MP). But it wouldn't.

Even the size of the lens points to this fact: the large sensor will require a lens that is many times larger and heavier for the same f-number and angle of view, and that lens will focus a far greater quantity of light than the very tiny lens on a digicam. When they are both displayed or used in the same way, the large sensor will have far less noise, despite the smaller pixels.

Acording to Canon larger pixels colect more light, requires less amplification, there for less noise.

It's true that larger pixels collect more light *per pixel*. But there are fewer pixels, so the total amount of light stays the same. Also, they do sometimes require a difference in amplification, but according to leading image sensor designers, that never results in additional noise: "No self-respecting chip engineer would allow that to happen."

The way I see it is like two shallow dishes of the same depth but one is say 40% larger, and put it out side when raining. Which will have more water, the lager one. In retrospect it's the same thing in sensors, the more light the pixel well collects in a certain amount time, the less it needs to be amplifed.

Here's a better analogy: 100 shot glasses compared to 10 shallow dishes. 1 shot glass has less water than 1 dish, but if you combine 10 shot glasses, it's the same as 1 dish.

[Fast Glass]

Ah, nowI havegot.


Canon's white papper threw me off. So the larger sensor has the better noise, right?

[Daniel Browning]

the larger sensor has the better noise, right?

Yep!

[hotsecretary]

So if I ditch my 40D and pick up a 5DII FF Camera my pictures will be sexier with my L glass?

[Mark Elberson]

Here's a better analogy: 100 shot glasses compared to 10 shallow dishes. 1 shot glass has less water than 1 dish, but if you combine 10 shot glasses, it's the same as 1 dish.
<p style="CLEAR: both"]

<p style="CLEAR: both"]Loved this analogy! Even I can't get confused with this one []

[Fast Glass]

Next time I think i'll take a bigger pinch of salt when I read of Canon's advertising!

[Jon Ruyle]

So if I ditch my 40D and pick up a 5DII FF Camera my pictures will be sexier with my L glass?
<div style="clear: both;"]</div>

Depends on who you're photographing.