Nick I hadn't thought of the 3rd party angle, good point

Sounds like I'd better sit down and have a large G&T (maybe a smoke) before I look at the prices of 35.5mm.

Also hadn't thought of a step-up so that could be a good option. I really only want it for when I'm using the camera near the sea here as the light can be interesting to say the least and also salt on glass as we all know is not a good combination