Focal Length vs Lens Assembly Length

[Victor43]

HhWould the further the camera is away from its area of focus would the focal length also be required to be a higher value thus making the camera lens assembly much longer in length ? So for example two cameras both focused on the same object one camera is closer to the object and the other is further away. The one which is further away would require a longer lens assembly to accommodate the higher focal length yes ?

 

[Syborg1211]

I think you are confusing some terms here. Focus distance is the distance away from the lens that you subject is. The focus distance is not directly related to the focal length.

A wide angle 28mm focal length lens can focus on a subject 10 feet away the same as a 200mm telephoto lens can focus on a subject 10 feet away. These photos will however have a totally different angle of view since the 28mm is a wide view it will be like a wide landscape type of shot while the 200mm will be much more zoomed in on the subject despite the focus distance being the same.

Now, if you wanted to do the above scenario but try to make the two shots look more or less identical, ignoring distortion caused by the different focal lengths, you could move the 28mm up close to your subject so that the frame looks similar to the 200mm shot from farther away. Focus distance will be different to accommodate for the focal length difference.

None of the above scenarios affect what you're calling lens assembly length. Changing the distance you focus on a subject does not change the size of a lens since all lenses can focus from at least a few feet to infinity.

There are many things that contribute to the overall size of a lens that a manufacturer makes. Focal length generally adds the most bulk but so does autofocus, maximum aperture, and image quality.