Optical equivalence theorem
Hey there little one! Do you know what optics mean? It means the science of light and how it interacts with things. Now, the Optical Equivalence Theorem basically says that, when you change the size of your lens but keep the same f-stop (like the same amount of light coming in), it'll give you the same image as if you hadn't changed the lens at all but instead had just moved closer or further away from your subject.
Think about how you see things when you're playing with your toys. Sometimes you hold them up close to your face and sometimes you hold them further away. Your eyes adjust to focus on them either way, right? Well, changing the size of your lens is like changing how close or far away you're holding your toy. Even though it looks bigger or smaller, your eyes (or your camera!) can adjust to see it in the same way.
Basically, the Optical Equivalence Theorem is just a fancy way of saying that, as long as you're using the same amount of light, it doesn't matter if you change your lens or move closer or further away – you'll get the same picture either way!
Think about how you see things when you're playing with your toys. Sometimes you hold them up close to your face and sometimes you hold them further away. Your eyes adjust to focus on them either way, right? Well, changing the size of your lens is like changing how close or far away you're holding your toy. Even though it looks bigger or smaller, your eyes (or your camera!) can adjust to see it in the same way.
Basically, the Optical Equivalence Theorem is just a fancy way of saying that, as long as you're using the same amount of light, it doesn't matter if you change your lens or move closer or further away – you'll get the same picture either way!