Although I have been a member for quite a while this is my first post. I am currently shooting with a Canon 1DS and Seacam housing with a large 9 inch dome port. When I first purchased the rig I was advised by a retailer (of underwter camera gear) that I should use a 2X diopter with the canon EF 17 - 35mm L series lens. I mainly shoot wide angle fish scenes. I note that some images are soft in the bottom left corner - but the rest of the image is otherwise sharp. I have since been advised by another retailer that I shouldn't be using any diopter for that lens. Any suggestions?
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Diopter or Not
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Hi Barra and Welcome,
I use Canon 1D and 5D cameras in Seacam housings.
The original thinking among those here was that using no diopter, was preferable to using a diopter in almost all cases.
I think this conventional wisdom has changed a bit since then. I recently received an email from Steven Frink, US retailer for Seacam, and he prefers to use a diopter with the Canon 16-35 and 17-40 lenses when he is doing CFWA work. I agree with him. For normal big animal WA, a diopter is usually not needed.
I'm not too sure about your older 17-35 lens, but I'd follow the same recommendation, use a good diopter for CFWA and no diopter for normal wideangle.
Canon wideangle lenses tend to have soft corners at f-stops below f8 - the 17-40L seems to be one of the better models.
Cheers
James
