Port body to use with 8" Ikelite dome and Canon 10-22mm

When I first purchased my u/w setup in 2006, the 8" dome (5510.45) came without a shade and the port body that came with it for the Canon 10-22mm zoom was the 5510.11. Today the recommendation is the 5510.22 port body. I have always been a bit miffed with the corner sharpness and distortion I get when shooting at 10 mm. My question is, is the 5510.22 port body an improvement or not? I have contacted Ikelite about this and their reply was:

"In looking at the port recommendations on your web site for the Canon 10-22 zoom, I see that you list port body #5510.22 for this lense but when I bought the 8" dome port in 2006 it came with the 5510.16 body. Would I get better performance from the 5510.22 on the 8" dome port or is this just a matter of fit? Possibly sharper edges in your photos at wide angle settings. We do not test lenses for the best optics since zoom lenses have floating nodal points and optically change as you zoom the lens underwater behind the dome. Our founder and the man who controlled the Ikelite website "Ike" died at the end of 2006. It could be that this lens was tested at some point afterward and it was determined that the slightly longer 5510.22 port was a bit sharper edge-to-edge at the lens's widest angle setting. The short answer is "possibly." Finally, when I purchased my 8" dome there was no shade, is it possible to add this now? No, the first domes did not have a slot on the side which is necessary for the four set screws that hold the dome on to screw into."

So I am reaching out the Canon 10-22mm lens and Ikelite 8" dome users on this forum for some feedback on this ... is there any improvement in edge quality using the 5510.22 port body over the 5510.16 port body? BTW I am using a 30D.

Best regards,

Charles

I use the setup very rarely, I prefer the 15mm FE for wide angle. Even with the 5510.22 corner sharpness is an issue. I recently tried using a +2 diopter but it will never be as sharp as a fisheye.

I am not sure which port body you use now: is it the shortest 5510.11 or the slightly longer 5510.16 ? I can measure the portbody if that is of any use...

Well my message was confusing, first I said I had the 5510.11 then the 5510.16. Now I actually looked at the port extender and it actually is ... the 5510.22, so that is the one now recommended for the Canon 10-22mm. I looked at my shots I just took in Guam and I see that when shooting at f8 and smaller that the edges looks somewhat better than at wider aperatures. I might have to spring for the Tokina that everyone raves about.

Dankje wel Gerard

Did you try using a +2 diopter? That is supposed to help corner sharpness. If you do a search there are many threads explaining

Such as

http://wetpixel.com/forums/index.php?showtopic=34309&view=&hl=&fromsearch=1

http://wetpixel.com/forums/index.php?showtopic=29378&view=&hl=&fromsearch=1

Good luck and graag gedaan

Thanks Gerard, read through all the threads, seems like a +2 diopter may help a little. I think stopping down below f8 helps more though. We have a Canon 15 mm at work, maybe I will play with that one as well.

I started shooting the Ikelite 6" dome port in 1974 with a 35 mm lens on a Pentax ESII also in an Ikelite housing (which BTW cost me $199.99 USD) so am familiar with the fact that the port creates a virtual image to focus on. I had to add a +2 diopter to allow the lens to focus on the virtual image. Once set I never had to focus the lens ... very handy.