Etienne said:
Bdube said:
This isn't quite the limit of what is possible. The cinema lenses are, in my opinion, a bit better. That being said, none of these are as robustly built as low-volume high precision optics made by some of the US companies. Some of them have almost inch thick steel barrels just as a shield for the internals.
"almost inch thick steel barrels" ... I have to call B.S. on that.
Here's some lenses from SPIE Optifab
http://i.imgur.com/76MINqM.jpg
The corning advanced optics is a relatively high speed telecentric lens for machine vision. It is a bit bigger than a 400/2.8, for size reference. The square portion near the end is where it mounts to the camera interface, its dimensions are about 4"x4" and the rear element is only 2" in diameter. This gives about an inch of padding all around.
Here are some big projection optics from Narvitar
http://i.imgur.com/SdzOM7H.jpg
Again you can see the leftmost lens, the barrel is much thicker than the front element. No element inside is larger than the front element. The barrel here is also solid steel.
It is cheaper to mill out less, and they are not concerned with weight.