how can smartphones have 108MP cameras, yet conventional cameras achieve better results with apparently less MP

Question

I get that more MP is better ends up being pure marketing. However I don’t understand why all cameras don’t bring 108 MP sensors or whatever. I’m confused.

In: 16

Answer 1

Here’s a weird analogy. Taking a picture is like ushering millions of tiny points of light, all different colors and brightnesses, into an enclosed space (say, a sports arena) through a single door and then making them sit down in the right order, and then quickly recording where they all sat before they disappear. Then your recording is a picture, and it looks more or less like the scene outside your stadium door.

The seats are pixels in your sensor.

The lens is like a group of ushers that tell each piece of light where to sit. When light comes in, they point in a straight line to where each photon should sit, and the photon changes course toward its seat. The lens isn’t perfect, though, so sometimes the photons go a little too far off track, or clump together around the edges of the stadium, etc. because the angle they “should” go is hard to distinguish.

Now, to improve the quality of your pictures, you have some options. One is to wait longer so multiple photons come and go, and average where they sat instead of taking one sample (long exposure). This will get blurry though if the scene changes at all.

One is to increase the number of seats. That way there are more possibilities of where a photon can sit, meaning more resolution. However, if you do this without making the stadium bigger, the lens’s job is much harder now. Even the slightest error in where it points will send the photon to the wrong seat, causing distortion.

If this happens, you could write some software that is good at catching errors in the record and applying corrections. (Apple is amazing at this).

Alternatively, you could make the stadium bigger, and make each seat bigger. Now the lens has a much easier job pointing each photon to exactly the right seat, even with the same number of pixels.

With a bigger stadium, you can also let more photons in at a time, meaning a larger sample even with a short exposure, and also fit a much bigger lens, which will be more precise (the analogy kinda breaks down here).

So they fact that we can capture a 100MP image from hardware that fits in our pocket is an amazing feat of engineering. But it does a bit of a different job than a full-blown camera.