Hello
I know this is purely speculative at this stage but here are some questions about the 67mm thread on the new housing for the Ikelite S90. My understanding is that the Inon UWL-100 28AD wide-angle lens is optimised for 28mm zooms but that Inon’s UWL-100 67mm mount lens is optimised for 35mm zooms.
1) Does that mean that the Inon 67mm 100WA lenses would require you to zoom to 35mm to use it on the S90 without vignetting (and therefore lose most of the WA potential)?
2) If so, does that imply that you would also need the dome for that lens make it useful again! (and therefore double the cost of the lens!)
3) Is there any chance that using the Inon 100WA 67mm with the Ikelite S90 housing would result in the same corner softness that is reported with that lens on the Patima G10 housing.
4) Is there any such thing as a commercially available 65mm to AD adaptor? If so, would that allow you to use the Inon 100-28AD lens to it’s full potential with the S90? I read somewhere that the 67mm mounts accept a much wider cone of light than the bayonet mounts. So presumably if Ikelite put a 67mm thread on their S90 housing, it is because a smaller mount would not have worked. Or would it work but just effectively keep the lens at a smaller aperture?
5) Reef are making a 67mm WA lens for the Patima G10 housing. Presumably this is optimised for the 28mm zoom on the G10. Is it likely that this will work better with the S90 than the Inon UWL 100 67mm WA lens (which is optimised for 35mm zooms)?
6) How far can you zoom to a longer focal length with an Inon Wide angle lens attached? I read a post that said there was no point in doing that because you lose the wide angle. But I’m still not clear about whether you could do it if you wanted to (e.g for a quick change in composition without having to remove the lens).
Sorry for the long list of questions. Any answers or speculations would be gratefully received.
Rob
1. Using the 1non 100WAL you will have to zoom into approx 32 to 35 mm to eliminate vignetting is my bet. No, you do not lose the wide angle potential because that is where the lens was designed to operate.
2. The dome is a wonder. The Inon 100WAL operating with a prime lens at 35mm provides an approximate 90 degree diagonal FOV, with the dome it is about 130 degrees. Without, the camera with the flat port would produce a FOV, diagonal, of about 45 degrees, with a dome correction for the prime lens it would be 64 degrees.
3. The corner softness in the Patima G10 is due to the G10 long zoom being backed too far away from the wet lens rear objective. As well, the large diameter of the G10/G11 lens does not mate well with the Inon. An additional factor with wide angle lenses is corner distortion, it is what it is.
4. No, to my knowledge there is not, however, I made my own and posted a thread on it to which there were no responses, I think I later removed the how-to picture links and I no longer have them, sorry. Here it is mounting my Inon 165AD fisheye to my Ikelite housed 67 mm threaded housing with Canon 570.
5. The photographs I have seen posted with that combination appeared considerably more distorted that the Inon 100WAL or Inon 100WAL with dome when used with my 570. Based on some very crude experiments I believe the S90 will work well with either the 28AD or the 100WAL. The S90 lens does not rack in and out like the G10/G11 and it is a smaller lens diameter (though much faster).
6. You are not supposed to zoom beyond the operating requirements with any wet wide angle lens, for the Inon 100WAL that would be 32-35 mm and the same for the Ikelite and Epoque types as well. Doing so will cause distortion and coke bottle effect for lack of a better term. Zooming a wide angle lens diminishes the "wide angle effect," yes, of course. I have had decent results out to about 45 mm equivalent on the camera which is about equal to the 28 mm native through the flat port, because I don't feel like calculating it right now, approximate.
The S90 has a very short zoom ratio, the lens barrel does not rack in and out very far compared to the G10/G11 thus allowing the lens to remain close to the port. The closer the lens is to the port then the closer it is to the wet lenses rear lens element and the less vignetting and distortion. As well, the S90 lens is relatively less diameter than the G10/G11 and it optically couples better with the Inon lenses.
I believe that the S90 will couple with the Inon 100WAL with good results and possibly with my AD adapter to my 165AD fisheye. You are not going to get dSLR results with these wet lenses. Of course we don't know for sure yet but Ikelite does say that minor zooming will be required, that does not surprise nor concern me but I guess we will find out for sure at some point.
N
