I am testing two different no rigid lens hood for my Canon 500 f.4 Is..; I have two ..one the same dimension of rigid but a bit less large so could more difficult put in right position..the other (working also with 600) is a bit longer.
Could it be a problem ?
Thanks
If you are concerned that the longer hood might vignette you might be justly so. Keep in mind that the non-rigid lens hoods sometimes end up not so perfectly round.
Any section that encroaches in toward the lens field of view has the potential to cause vignetting in that area. This becomes more likely to happen the longer the lens hood is.
Some of these wrap on lens hoods have a ridge that positions them on the lens, which will prevent you from sliding it back.