how do camera lenses have a “resolution” and a mega pixel count?

Question

I get details can be blurry on a bad lens but how is this like pixel resolution?

CCTV lenses are often 1-5 megapixel lenses. How can a lens have a mega pixel count?

What does it mean for a lens to “resolve” more detail? Is this just about sharpness?

Also when buying DSLR lenses how can you tell what their resolution will be?

Thanks 🙂

In: 0

Answer 1

>Is this just about sharpness?

Yes.

Imagine a infinitely small point light source, like a star. A lens will focus it to sensor, but not to a infinitely small dot, but more like a blurry round blob like so: [https://en.wikipedia.org/wiki/Airy_disk#/media/File:Airy-pattern.svg](https://en.wikipedia.org/wiki/Airy_disk#/media/File:Airy-pattern.svg)

Now, the question is, how large is a pixel in relation to this blob? If a blob is bigger then a pixel, then limiting factor of resolution is the lens, adding more pixels in the sensor does not get you sharper image.

So the MP rating of a lens is really a recommendation to what sort of sensor it’s built to be used with and an indicator of how sharp and image it can generate.