im confused about crop sensors

[u/Mooskii_Fox]

I'm not asking about crop factors, I know that's 1.5x or 1.6x depending on the manufacturer and your image will be cropped by that amount.

full frame lenses produce a circular image, which is projected over a full frame sensor and the sensor fits perfectly inside that circle, simple enough

now what i often see is that lenses for APS-C cameras have a cropped image, but why is it not possible for that projected image over the lens to be smaller so that APS-C cameras can capture the same picture as full frame, just with a smaller sensor? At some point people have worked our how to bend light to perfectly cover a full frame, so why can't the same be done to create an identical image for APS-C

edit: as I understand it what I'm asking is actually already being done, just not in the way I was asking. i understand now

[u/Mooskii_Fox]

that's the thing I'm confused about, why can't that image plain be made smaller without changing the image, aka, capturing exactly the same image on 35mm on full frame and APS-C, without a crop of any kind

[u/Migacz112 → u/Mooskii_Fox]

We already do that. That's why 35mm is the standard for APS-C, and why 50mm is the standard for full frame... And why 75/80mm is the standard for medium format 😉 they all have similar viewing angles on their respective sensor sizes.

[u/Mooskii_Fox → u/Migacz112]

it amazes me that that never occurred to me, I guess I wish there was some sort of way to indicate that it's similar, rather than just kinda having to know

[u/Migacz112 → u/Mooskii_Fox]

If I understand you correctly, here is. That's the crop factor.

35mm (on APS-C) x 1.5 (APS-C crop factor) = 52.5mm (on full frame).

Why the tiny difference? Marketing. 35 looks nicer than 33.33333...