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Showing results for tags '17-40mm 1:4 l usm lens'.
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Hi everyone, I'm hoping some of you might be able to help me out. I recently upgraded to a 5D mkiii Nauticam system. I'm shooting with the Canon EF 17-40 1:4 L USM Lens, 50mm extension ring, and a Nauticam N120 8.5" acrylic dome port, as is the suggested setup, but every image has severe vignetting, regardless of the focal length. At first I thought it might just be because I was shooting primarily at the wide end, but after experimenting I realised that it doesnt matter. The wierd thing is that when I first used it i was shooting split shots in mangroves and there was no issues. But while diving and snorkelling, all images have vignetting. This is the first time I have used a rectilinear lens underwater, having only ever used the Tokina 10-17mm previously, so I'm pretty confused. Is it just the lens? Could it be my Autofocus settings? Could it be that the second hand dome has been polished too much so that now it has thicker edges thus creating the blur? I'm really at a loss here, and after investing so much money to upgrade, I'm really disappointed. So I would really appreciate some feedback guys!!! Thanks in advance.