Eventually they developed screw type lens mounts that allowed for changing lenses, and lenses of different sizes were developed. It was quickly discovered that if you made the focal length shorter, the angle of view got wider, which meant more would fit in an image at a given distance from the camera, and depth of field increased. News photographers would often use these benefits by fixing short lenses on their cameras. Unfortunately there are also a disadvantage, straight lines would appear curved, and perspectives would change, an item that was close to the camera would appear much larger then normal, and an item further away would appear much smaller. Photographers have used both of these traits to advantage.
By the same token longer lenses would have a narrower angle of view, less would fit in the image at the same distance, straight lines would not be affected, but the perspective changes would be reversed, flattening the image. Portrait photographers learned quickly that using a slightly longer than normal lens, was more flattering, with a 35mm camera 85mm - 100mm is about right. In the 1960's they developed the bayonet mount, which made lenses easier and faster to change. Unfortunately where with screw mount lenses nearly all camera's used the same 49mm mount, each bayonet could be a little different. You could no longer use a lens made by one manufacturer, on another makes camera. Although third party lens makers would quite often make lenses with different mounts on them, and one company Tamron made adaptall lenses which could be used with different makes of cameras, using different adapter rings.
This weeks image of a white lion was taken at African Lion Safari, last year, from a car with the windows closed, with the 70-300mm lens at 85mm on the Canon 300D. It's a nice image, of a cat on the prowl, it's funny to see that a house cat uses similar methods when they are hunting.
I think that is all for now....