If your Ikelite housing has the 67 mm threaded port then you will use the Inon (Type II I think it is) thread on wet mount lenses. The dome port can be added to increase the view angle from 100 degress approximate to nearly 150 degrees approximate. Why approximate, it depends on your camera, it's native lens, it's set back from the port and to what degree (if any) you have to zoom to prevent vignetting. The Ikelite lens is similar to the Inon (which is high quality and hard coated) but it will not accept the Inon dome port for super wide (near fisheye) shooting.
Some Ikelite housing have a smaller 40 something other threaded port, those will use an adapter for either the Inon AD series or threaded series. I know it is confusing. Inon makes essentially three series of lenses:
Inon AD lenses, for small cameras with a typical native camera lens of about 34 mm focal length. Typical use would be something like the canon 570 and canon hosuing.
Inon 28AD lenses, for larger cameras and those with a 28 mm native focal length. Typical use on various Olympus housings.
Inon Type I and Type II thread on 67 MM lenses. I think Ikelite typically would use the Type II (if they have the 67 mm threaded port. Typical use on Ikelite housing and various G9 and similar applications.
The "typical" I gave as an example, each camera and housing must be evaluated for the correct set up on it's own merit.
Does that help?
N
i just got an SD870 IS and an Ikelite housing the housing can add WA lenses withe the adapter ring, the 870 is 28mm at its widest,will an additional WA lens be of any benefit or just be redundant, using just the camera flash Ikelite recomends a slight zoom out to avoid a "shadow" in the corner so will I lose some of the camera's wide angle capability, and will an external lens help regain this. I'm thinking If the 870's wide angle is going to be sufficient I can use the money better to invest in a DS-51 and avoid the issue of any "shadow " effect that may occur.this is my 1st rig, I appreciate any and all input.
