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+--- Thread: Used lens: diaphragm iris not perfectly circular (/showthread.php?tid=5604)
Used lens: diaphragm iris not perfectly circular - stoppingdown - 09-22-2023
I've spotted a defect of the Samyang 75mm F1.8 lens that I bought a few days ago: the diaphragm iris is not perfectly circular. The defect worsens as far as you stop down. With the limited testing I've done so far, it has apparently no effect on photos — clearly it would affect the shape of bokeh balls, but at least up to ƒ/8 it's not noticeable (I will try to specifically test with point of lights to get more info).
Can it cause other problems? Would you keep a lens with this defect or return it?
Thanks.
Added: what about the fact that the defect could be a sign of a potential failure in future?
RE: Used lens: diaphragm iris not perfectly circular - stoppingdown - 09-22-2023
Actually, with a bright light point I can see that the defect is more visible than I thought...
RE: Used lens: diaphragm iris not perfectly circular - toni-a - 09-22-2023
I forwarded your photos to an expert (Canon repairs guy) there's nothing to worry about
RE: Used lens: diaphragm iris not perfectly circular - stoppingdown - 09-22-2023
Thanks Toni.