The bayonet mount has 3 flanges sticking out, and all are the same radial length. However, they are not spaced equidistant along the mount. There is one gap that is roughly 50% longer than the others. The lens cap is designed so that there are 3 internal flanges of the lens cap, and 2 are the same length, but 1 is extra long. This makes it so that the lens cap can only fit on in one specific orientation.
You can resolve this issue by removing the extra plastic from the inside of the lens cap such that it is the same size as the other flanges, then you can put the lens cap on in any orientation. As far as I can tell, there is no benefit to the Canon system for making the lens caps intolerable.
Aug 06, 2020 at 07:59 PM
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