E300 and 14-45

Lo all.

I just bought an Ike E300 housing, 14-45 zoom lens, 35mm macro and am busy waiting for my main strobe to arrive. I have the Ike recommended dome and flat port for each lens. I have a +4 dioptre Hoya on the 14-45, as recommended by ike.

I did some testing in natural light and seemed to get some pretty obvious vignetting (as in darker shaded corners not mechanical vignetting) at the 45mm end on the 14-45, when shooting at f3.5 and 1/125. Is this just to be expected or is there something possibly wrong setup wise? Im wondering if I have the wrong kind of dioptre or something like that, or do I just need to try and avoid high f stops if Im using the 45mm end? I can correct it using photoshop fairly easily but be nice to avoid it in the first place where possible.

Im trying really hard to stop convincing myself I really want the 14-54mm, so any help would be appreciated.

Otara

I have not used that particular setup so I can not say if it is to be expected but here are some things to try to pinpoint the problem.

On land with camera not in the housing shoot @ 45mm without diopter and with the diopter. Then shoot on land with the housing and port on with and without the diopter. Then shoot underwater with and without the water.