Size of the sensor

Hi friends!

I always had this doubt: The clearness that we see in DSLR cameras doesn't see in the smallest ones. Is it because of the size of the sensor?
To what extent is the size of the sensor important on this time?

It's not the size of the sensor, but the magic in it...

Seriously though, the real reason P&S camera sensors have so much noise is the pixel density. Take a 6MP DSLR and a 6MP P&S. The sensor size is much larger in the DSLR, leading to larger pixels that are more receptive to light as compared to the tiny little sensor in the P&S. This is where the noise comes from more or less.

So while yes, the size of the sensor is important - so is the density/size of the pixels.

If what you mean is "Are the clean images produced by a DSLR due to it having a larger sensor", perhaps yes, but of course the quality of the camera and sensor plus some other factors count too.

By clean images you need to be a little clearer about what you mean as clean. Less noise, better color, contrast or definition? What do you mean by clean, because maybe the lens is playing a role too?

I think it's mostly in the lens until you start shooting in more difficult situations. My old Nikon can produce a picture every bit as clear/sharp/colorful if I keep the ISO at 40 and if my subject is stationary, and the lighting is good, but if the lighting gets dicey, or the ISO needs to creap up, or the subject is moving, the Nikon just can't keep up.

John_T wrote in post #5881217
By clean images you need to be a little clearer about what you mean as clean. Less noise, better color, contrast or definition? What do you mean by clean, because maybe the lens is playing a role too?

Hi John!

Yes. I think that is the absence of noise that makes more difference.

In DSLR almost always the tones are very homogeneous, cleaner.

Although I think the lenses also work well, according to the explanation of our friend Double Negative, where we can conclude that the sensor is without doubt very importane in this process.

You don't think this way too?

Yes, the sensor is key, however the quality of the lens determines the quality of image that lands on the sensor, so really both are important in aquiring a clean image.

It's the pixel size and the lens optics that play very important roles in IQ. Think of pixel size on the sensor like lens apertures. The larger it is the more light can transmit. The more light it gets the more accurate it can be. The other factor is the electronics involved. The smaller the pixels and the closer they are together the more they can interfere/talk to each other which can throw off the accuracy as well. i suspect that with smaller pixels and less light hitting them because of size they might have to do the equivalent of cranking up the amps that transmit the data it receives... which is the equivalent of cranking up the ISO.

Lens, sharpening, contrast, and of course, sensor size (specifically size of the photosite)

A lot has been written here about the relationship of photosite size and noise - and there is a physical boundary based on the size of a photon, and on the other side just how much the electronics can compensate for the noise inherent with a smaller photosite. I guess the "hard and fast rule" really relates to a gray area where various compromises made can produce similar results.

And then, you have the concept that high end cameras/sensors are out resolving some of the better lenses out there today.

Dermit wrote in post #5885637
...i suspect that with smaller pixels and less light hitting them because of size they might have to do the equivalent of cranking up the amps that transmit the data it receives... which is the equivalent of cranking up the ISO.

Yes Dermit!
Really. I had already thought before of this. Especially in the amps theory.

In the days of film, larger format was always better for image quality, and smaller film grain was always better for image quality. The size of pixel is like film grain size. The size of sensor is like film format size. Both pixel size and sensor size interact to impact the total performance, it is not merely one or the other. Digital adds in the signal:noise characteristic, that smaller pixel makes for greater noise in the image, particularly at higher ISO values.

Wilt wrote in post #5886571
In the days of film, larger format was always better for image quality, and smaller film grain was always better for image quality. The size of pixel is like film grain size. The size of sensor is like film format size. Both pixel size and sensor size interact to impact the total performance, it is not merely one or the other. Digital adds in the signal:noise characteristic, that smaller pixel makes for greater noise in the image, particularly at higher ISO values.

Close, you are right in saying film grain size smaller is better, but when it comes to pixel size on the sensor the bigger the better. Large pixels on sensor do not directly equate to larger film grain. The pixel sensor sights just gather light. They in turn convert the light/photons to an electrical signal which in turn ultimately gets converted to a color/tone on the monitor, then maybe a print. But the pixel site itself, the size, etc does not directly correlate to the size of that equivalent data on a monitor or print. So it's not exactly apples to apples here.

Wilt wrote in post #5886571
In the days of film, larger format was always better for image quality, and smaller film grain was always better for image quality. The size of pixel is like film grain size. The size of sensor is like film format size. Both pixel size and sensor size interact to impact the total performance, it is not merely one or the other. Digital adds in the signal:noise characteristic, that smaller pixel makes for greater noise in the image, particularly at higher ISO values.

It's kind of interesting that in digital it is the exact opposite of what it was in film days. With film large grain = noisy image and small grains = smoother image while in digital, large photo sites = smooth image and small photo sites = noisy image.

Dermit wrote in post #5887261
Close, you are right in saying film grain size smaller is better, but when it comes to pixel size on the sensor the bigger the better. Large pixels on sensor do not directly equate to larger film grain. The pixel sensor sights just gather light. They in turn convert the light/photons to an electrical signal which in turn ultimately gets converted to a color/tone on the monitor, then maybe a print. But the pixel site itself, the size, etc does not directly correlate to the size of that equivalent data on a monitor or print. So it's not exactly apples to apples here.

You have a bunch of 'APS-C reach advantage' bird shooters who very staunchly argue the point about the same square millimeter area and the 10MPixels of 40D vs. the fewer than 8 MPixels in the same space...the 5D having larger pixels is not viewed as an advantage in that situation!

gjl711 wrote in post #5887269
It's kind of interesting that in digital it is the exact opposite of what it was in film days. With film large grain = noisy image and small grains = smoother image while in digital, large photo sites = smooth image and small photo sites = noisy image.

yeah, it brings home the point about different levels of assessing 'noise'...not the same in both

Another thing that I thought now. A thing pulls another!


Sensor smaller = more aggressive lenses.

More aggressive lenses = more distorted image.

More distorted image = larger probability of erros (noise) on the part of the internal software of the camera.