Woody's Diopter Technique

When pushing on the diopter underwater how important is it to ensure that it is perfectly straight against the port? Obviously I think its important but am a bit afraid to push somewhat hard underwater in case water gets past the oring.

Once you are at depth, the water pressure is going to be much greater than the pressure you would apply pushing the diopter on.

Phil

I hadnt thought of that! When I was pushing it on at home prior to going out I saw the port (Ikelite) move a little and was worried that the seal would be broken even if only momentarily.

Thanks!

The lens has holes in the rubber mounting because it needs to have water on both sides. So the pressure doesn't push it on underwater.

James

The important thing is to ensure that there is nothing but water between the port and the diopter (no air, crud, etc.). I use the 100 mm (diameter) on a 110 mm flat port. I had the 100 and too cheap to buy a new one. If the skirt is catawampus on the port, it is possible to vignette. As previously noted, there is no pressure differential..

It was the vignetting (sp?) I was worried about. The first time I used the lens it seemed to me that there were some "softer" edges on some of the sides of pictures but I couldnt be sure that they werent just fine silt or a salinity differential.

CATAWAMPUS, what a great word and the cause of most flooded equipment. This word should be added to the underwater photographers dictionary.

Phil

Hi IslandBound,

I only mention the possibility of vigneting when using a diopter with a smaller diameter than the port diameter. I use and have used the 90 & 100 mm diameter diopters on the respective ports (for Nikkor 60 & 105 macro lens) on a 35 mm camera and have not noticed any softness in the corners. With a smaller digital sensor, this would be even less of a problem. I don't seem to have soft corner problem with the 100mm diapter on the 110 mm port (Nikkor 60mm), but I will give it a closer look.