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Canon EF 400mm F5.6 L USM rear black plastic - how to remove?

Manzur Fahim

Well-Known Member
Hello everyone,

Hope you are well.

I am trying to remove the rear black plastic from the 400mm F5.6 lens, so it won't vignette or not as much as it does now with GFX 100S. I unscrewed it, and the contact plate, but the black plastic kinda gets stuck, not enough space to take it out. Anything I am doing wrong? Is there any specific trick I need to do?

Many thanks in advance.