Yeah, you’re right @jamesstaddon, but this is what I was trying to say.
Since I don’t have a full frame camera, when I see someone who does, saying that a photo was taken at 24mm on a full frame camera, it would take a (approximately) 15mm lens to replicate it on my crop sensor.
Or lets say you and I are standing next to each other before a scene. You with your full frame, and I with my crop sensor.
The cameras are set up right beside each other, and you have your 24-105mm lens(at 24mm) on your camera.
To get the same exact frame, what lens focal length lens would I need?
It would be about 15mm, right? No clue if that makes sense, or even if I’m correct, but am I on the right track?