I've been scratching my head over which wide-angle lens I should use for underwater use with the GH4 and the Zen 170mm. I have been reading about dome ports, virtual images, rectilinear lenses, corner sharpness, close focus distance, mathematical formulas, etc, etc. Interesting stuff but I have not found a clear answer.
I own the Panasonic 12-35mm f2.8 and it's a great lens, at least above water. It should work well in the Zen 170mm dome. Should focus OK and be sharp in the corners. I can test this lens next week when I get the GH4 housing.
But, 12mm (~24mm) is not very wide for shooting large creatures up close. Might be OK but I suspect that I'll want something a bit wider.
One option is a fish-eye like the Panasonic 8mm. But I am not too crazy about the fish-eye look for all my WA shots.
Another option is a full-frame lens (Nikon, Canon, etc) on a 4/3rds Metabones speedbooster. Could be nice for low DoF but probably loses all AF, lens corrections and stabilisation functions?
So, then I get back to what I first thought would be best lens: the Panasonic 7-14mm f4 lens. Great focal range for underwater WA (35mm ~ 14-28mm). All the Panasonic functions work: AF and lens corrections. The close focus at .25M should focus fine, although it'll right on the near focus limit of the lens.
But, here's where my reading about dome ports made me uncertain. What will the corner sharpness of the Panasonic 7-14mm be like in the Zen 170mm port?
I've read about a "rule of thumb" not to use a rectilinear WA lens greater than 100 degrees angle of view in a dome port or you get soft corners. The 7-14mm has an angle of 114 degrees at its widest. Is this going to rule out the Panasonic 7-14mm f4 lens? Could it be OK from about 10mm to 14mm in its zoom range?
Of course, one answer might be: try one. But, it's an expensive lens to buy for a pool test that might prove it unsuitable. I would have very little use for this lens if it doesn't work underwater. And, I'm sure no shop in Singapore will lend me one to test.
Has anyone tried the Panasonic 7-14mm in a dome port?
Edited by peterbkk, 18 July 2014 - 03:51 AM.