How do you use the 100-400 CANON LENS tripod ring mount

SOURCE: I have a Canon EF 300mm f/2.8L USM Lens

Here is a link to many Canon products in PDF form: Canon Parts Lists


Unfortunately, the only 300mm 2.8 lens listed is the IS version

The procedure is not that complicated, but you need to pay attention to the connections on the circuit board. The mount is removed, and you need to remove the small screws that hold the connector board to the mount ring first.

I cannot do live chat due to I use a Mac, but I will monitor the thread if you have questions,

Kevin

SOURCE: dropped the lens, the focus ring won`t move

You can send it to the canon-service but i think it will be cheaper if you buy a new or used one.

SOURCE: When I point the lens down it just drops into full

The lens is damaged inside, no way to adjust that outside and it definately shouldn 't do it. You need to get it looked at.

Testimonial: "Thanks for the info, I'll get it looked at when I get back home."

SOURCE: I have a Canon 100mm macro lens used on a Canon

It seems that you have either a faulty lens or one which is performing outside of the minimum quality standards. You have clearly done everything possible to try and eliminate all other causes. Looking at the firmware updates for your camera, none of them mention an issue involving your lens but you may wish to ensure that you have the latest firmware anyway.

All you can do is to contact Canon customer care to request that the lens is exchanged.