You can use the focus gear for the 60mm macro in the 12-50mm port.
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Posted by coroander on 19 February 2014 - 11:25 AM
The soft corners are because the curved virtual image that we are photographing has the corners much closer to the sensor than the centre. We rely on depth of field for the corners to be in focus (but it's often just not enough). I think that the diopters work by causing the image to appear further away to the camera (the camera focus changes from say 0.4m to 0.8m). This, of course, also allows you to get much closer to your subject because the minimum focus distance is now much closer than where the camera thinks it's focusing. By making the virtual image appear further away, the focus distance is also at a place where depth of field is greater and the corners can now be sharper. That's my take on it, i've never read why this works, but this seems reasonable.
Posted by coroander on 13 February 2014 - 08:04 PM
Over-and-unders with the Panasonic 8mm FE behind the Nauticam 4.33" dome:
If you instead focus on something in the water, nothing above water will be in focus unless it's almost touching the dome. And if you focus on something at any distance from the camera above water, nothing underwater will be in focus.
* you need to have your camera configured to separate focus from the shutter ( http://wetpixel.com/...showtopic=48625 ), we still use autofocus to focus, but with the camera in manual focus mode and using the back lever on the Nauticam housing to trigger focus.
Posted by coroander on 02 February 2014 - 09:36 AM
I won't use this lens underwater again without the diopter.
Just looking at the geometry of the 52mm +5 with a step up ring and it seems like there should be no large difference between doing this and using a B+W 46mm +5 directly. I think the 46mm is preferable and may produce somewhat better results.
The focus distance changes very little behind the dome -- since the virtual image only extends from about 0.10m touching the dome to about 0.22m (maybe 0.26m) at infinity, and for distances from 1m and beyond, there's very little change at all. So no reason to believe there won't be a similar improvement at all focus distances. I'll try a close focus test (at minimum focus for no diopter) sometime.
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