Wide Angle Lens Distortion

[geokr]

I'm new to underwater photography and just purchased my first rig, an Equinox SD6 housing with a dome port and a Sony SR12 camera for both videos and stills. The set came with a .45X wide angle lens. Having a snow day on Monday I took the camera outside to take some pictures with the wide angle lens attached and in the 16:9 format. As shown in the attached sample, I found that with the zoom all the way back (wide) there was significant blurring on the left and right thirds of the frame though the center third was in focus. This is the case with shots at a distance or as close as a few feet.

Is this typical or did I get an unsuitable lens? Will the dome port correct this when installed? I haven't tried this installed in the housing yet but would not expect it to improve. Seems to me that the whole purpose of a wide angle lens is defeated if the sides are blurred.

 

[Nemrod]

Not sure on that but I have had P&S type cameras with the matching OEM wide angle and telephoto lenses and have seen exactly that same thing with them, thus my fascination with wet mount lenses which seem to avoid that severe distortion.

You may need a diopter, I had a video camera once that required a close up diopter when used inside the dome port of the housing with the wide angle attachment which eliminated then much of that fuzzy focus on the periphery.

N

 

[geokr]

OK - I know I'm really showing my ignorance here - but what's a diopter? And where do I get one? Do they come in different sizes, focal lengths, etc? I asked Equinox to replace the lens but the new one (clearly an aftermarket no-name brand) is just as bad. Thinking about dropping $200 for a genuine Sony brand but am worried that I might get the same results. A diopter would help?