So what does it matter that a 35mm chip with 5um pixels is bigger than a m4/3 chip with 5um pixels?

Sensor size is related to image quality, but it has nothing to do with how much light it "gathers."

It matters because the 35mm sensor has 384% the surface area of a m43 chip so it will gather 384% as many photons coming from your subject. Using lenses that give same FOV and aperture that is. If we keep the same 5um pixels, with the larger sensor we can have a higher resolution and/or do some pixel binning to reduce noise and artefacts. Both are improvements to image quality we can only execute because we have captured more light.

Do you mean exposure?

It does not. That would only be true if you binned every pixel to make a single pixel image. What matters is what each pixel collects.

It is the aperture that determines the illumination at the image plane, regardless of sensor size. A lens from a 35mm camera will work on a m4/3 camera without the need to compensate exposure because of chip size.

That is not what this conversation is about nor is resolution directly related to illumination.

Pixel binning is not either--binning is not adding light, but sensor signal. I can bin any chip.


No, I mean how much light it intersects.

You have a unique view of photography.

And those pixels form an array that covers the entire sensor. What matters for light capturing performance of the entire camera is a) how many photons per area unit of the sensor are converted into photons and b) how large the entire sensor area is.

That is true for aperture, which is the flow density or intensity of light. Per area unit of the sensor plane we will get the same amount of light at same aperture.
When both sensors cover then same field of view however, per degree steradian of the subject the larger sensor will have more sensor area (or more pixels if you like to think in pixels) to register the incoming light.

Two same lamps are brighter than one lamp. Two same pixels capture more light than one pixel.

With pixel binning at this point we do not add light. We just make use of the light we have already got due to a bigger sensor.

The bigger sensor intersects more light. More water flows through a bigger pipe.

You have a peculiar view of physics. ;)

No, what is important is what individual photo site capture, the sensor size is irrelevant.

Right. What is important is the light hitting the pixels. The pixel are isolated elements.

Irrelevant. Pixels work in isolation. How many you have do not make any difference.


But the image of each lamp are the same brightness. And as I said it is about pixel size, not sensor size, which you seem to agree with now.


Take a 35mm and a m4/3 sensor both with 5um pixels and bin them, both end up with the same result. Sensor size is irrelevant.


But don't you want an image?

The sensor size does not restrict the amount of light entering the system, but the f-number of the system.


Actually, as far as photography goes, I have an excellent grasp of physics.

Sigh. I'm so tired of this argument. It goes on and on and on, on every photography forum in the world, I think. No one ever convinces anyone else, and it doesn't really make a damn bit of difference.

I shoot with what I choose, and work within the confines of that system. If I'm shooting with m43, it matters not to me whether full frame gathers more light, or is "better" in any other respect. What matters is making the most of what I'm using.

To pretend that FF is "best" in a vacuum, without considering the trade-offs that FF entails (cost, size, weight, difficulty in getting adequate DOF (!!) and more is a fools game.

Every system involves trade-offs. If you don't like the trade-offs m43 involves, go elsewhere. If you do like those tradeoffs, then stop talking about something else on this forum.

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I'm not lazy. I'm energy efficient.

You are talking light intensity, i.e. amount of light per unit of sensor area, amount of light per pixel. I am talking amount of light captured per steradian of field of view, i.e. within a given field of view.

Example: we have a FF and a m43 camera and we use both for the same shot at same FOV same aperture, eg a face. Per sensor pixel, both will indeed capture the same amount of light.

We do however not care about the pixels but about the image they constitute. Therefore we print both images at same size. Per area unit of the print, the FF sensor will have captured more light, period.

This is not about what is better, it is just about what is what. Knowlege doesn't hurt does it?

/// edit: lost the quote the first time around

Who are "we."

And it is entirely irrelevant.

Who said anything about being better? I am simply telling you what is what.