The Canon new FD 300mm f/2.8 and 500mm f/4.5 both take the EH-123 hood which has a 123mm inner diameter. Of course, it's very expensive now.
This is a black powder coated steel 6 inch to 5 inch duct reducer. The inner diameter of the small side is 123mm which is the same or 1mm more than the outer diameter of the rubber ring on the end of the lens.
Is it a good idea to try to use this? Price comparison is about $20 vs $200 for the real hood. Do you think I should attach it with a hose clamp or try to shim the inside? Recommendation of shim material? Thanks.
This is a black powder coated steel 6 inch to 5 inch duct reducer. The inner diameter of the small side is 123mm which is the same or 1mm more than the outer diameter of the rubber ring on the end of the lens.
Is it a good idea to try to use this? Price comparison is about $20 vs $200 for the real hood. Do you think I should attach it with a hose clamp or try to shim the inside? Recommendation of shim material? Thanks.

