with low light performance of the 5n, what is the appeal of full-frame?

Started Nov 10, 2012 | Discussions thread
RicksAstro Veteran Member • Posts: 3,646
Re: Smaller pitch = higher noise = mathematics

tesilab wrote:

Of course it is true that better technology has been yielding better results, and we have some pretty good looking small pitch pixels today. But identical technology applied to larger pitch pixels will produce less noise by definition. It is a matter of sampling error.

The fact that, for the same output resolution, the noise difference is very minor compared to less meaningful 100% crop comparisons doesn't change that.

All things being equal (which they rarely are) smaller pitch pixels will increase the error in the signal.

A single pixel covering the entire sensor will have less noise than a 16MP sensor, but will also have significantly less detail

It is a rule that increasing detail also increases noise. This is true when sampling images, and this is true when attempting to sharpen them as well.

I said for equal modern technology, pixel pitch is almost irrelevant when you are looking at a given area of the image (or an entire image at the same magnification).

While the single pixel will indeed have more noise with higher pitch sensor (due to sampling error and possibly read noise), if you are looking at the same portion of the image, it will have more pixels (samples) to average together with the higher pitch, nullifying this error. Say if you have a sensor with 1/4 the pixel count, one pixel with the larger pixel will be covered by 4 pixels with the finer pitch.

Don't believe me? Lets look at DXOMark's SNR 18% ratings with "Print" selected, which normalizes the data to an equal viewing size. THe Nikon D800 and D600 are virtually identical in sensitivity despite the D600 having larger pixels and released after the D800


Let's look at the NEX-7, NEX-5N...same exact SN18% despite pixel pitch differences:


If you select "Screen" which gives a per-pixel view, the finer pitch cameras are noisier per pixel. This is mostly because it is measuring a smaller area and the sampling noise is greater.

It used to be that larger pixels gave a much large proportion of the sensor surface being light sensitive due to the circuitry taking up more of the overall area with smaller pixels. But the backlit sensors and microlenses have all but nullified this effect.

So with higher resolution sensors, the user has the choice of trading off resolution vs. noise by resampling. With lower resolution cameras, you have lost some of the resolution and cannot recover it, but you do get smaller files if that's important to you.

The Nokia 808 is the perfect example of this...a tiny, tiny 41MP chip that outclasses all other camera phones. Yes, it looks like doo-doo at the pixel level, but the overall image blows the others away when compared to others at the same magnification.

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