Canon Cinema Prime lenses 4K image quality

[Stefano Stroppa]

hello guys!

I've got a question, it might be a stupid question for some of us, still it bothers me right now!

I was browsing some Canon Cinema Prime lenses, and I read: "they offer brilliant 4K image quality"

my question is: what does that mean? I mean, how do they calculate that the lens offers a 4K image quality and not for instance a 2K?

thank you so much :)

[Max Field]

The visual the lens provides is sharp enough for a 4k sensor to make a difference in recorded image quality. For example, an old camcorder lens for a Canon XL1 has elements that are sharp enough for 480p, but if you were to adapt it to a 1080p sensor, the image would come off a bit blurry.

[Phil Rhodes]

One reasonable assumption is that they're claiming the lenses have reasonable MTF at the required resolution, I guess. MTF (modulation transfer function) is a measure of how blurred-together a black and white stripe is at a certain pitch. As the stripes get closer together, they eventually stop being black and white stripes and become various shades of grey. At some point, it becomes meaningless to call them stripes. And at some point before that, someone will decide there's enough contrast to call the lens functional at that resolution.

[Stefano Stroppa]

now it's much clearer! thank you a lot guys!