Vignetting Issue

Im new to the forums and to shooting housed SLR's. Ive shot digital point and shoot and hated it. I plan on housing a Nikon D70 before my next trip in October, This picture is one of the reasons why. I wasted 4 rolls of film, all vignetted and out of focus (attempted setting the hyperfocal and botched the attempt).

All the photos are from different trips but the camera is essentially set up the same.

17mm

Ikelite dome port

1st was taken using the flash

2nd and 3rd natural light no flash

I dont know why i have the vignette in the corners of the third picture, every one of my wide angle shots on all 4 rolls from bonaire had this.

Coud it have been an issue whith setting up the hyperfocal distance? This makes no sense to me.

I read in another post that flash could cause vignetting, but hey, no flash.

Did the port cover get twisted funny, and these are the edges? This makes more sense but i'm having a hard time accepting that answer, particulary since it did not happen on any other pictures from any of the other trips. It shouldn't show no matter how the hood is turned.

I doubt is was sunlight at the surface either, vignetting occured at 100ft as well.

Your help is appreciated.

You get vignetting when your lens/dome port set up is incorrect. You are in essence "seeing" the corners of your image sensor (film). You get this when the distance from the nodal point of the lens to the dome port is incorrect. I believe too far away.

You will get this with digital as well. But with the feedback of digital you will notice it earlier. Hopefully to correct before the end of your trip. This is why you use your housing manufactures recommended dome port and lens combination.

I had a similar problem with my Nexus 12-24 port after over tightening it with the result was that the "port shade" was further around than it should have been (correctly aligned it should have been at the top of my port).

Port shade orientation is likely culprit. Notice it has a top and bottom position to allow for the picture corners............

Thanks for the input, I think the port positioning was the problem. I just overlooked it as an issue.