This is just idle curiosity, I suppose, but many of you are much more technically adept than am I. So maybe someone can explain:

I happened to notice that a Nauticam wwl-c on a Nikkor 24-50 lens has a converted field of view of 130 to 81 degrees. The wwl-1 with the same lens and camera has a converted FOV of 130-72. I would have thought that any difference might have been on the wide end since with the wwl-c, the lens can be used at 24mm while on the wwl-1, the soom range should be limited to 28mm on the wide end.

I am guessing it is just a result of the optical construction, but it confounds me. Perhaps the optical design accentuates the wide end (to allow 24mm) and that resulted in a reduction in the effects at the long end?

If this is a technically stupid question, please be gentle.

The WWL-1 is designed to use with 28mm lenses min and the WWL-C 24mm and at shorter than design focal lengths they will vignette. However they are designed to produce the same field of 130° diagonal field at their designed minimum focal length. This means they have different magnifications, the WWL-1 is about 0.35x while the WWL-C is about 0.41x to both achieve 130° diagonal at the widest, which happens at 28mm and 24mm focal length respectively.

With the higher magnification of the WWL-C it has slightly more reach on the long end. if we are looking at the 24-50 lens, it will vignette between 24 and 28mm focal length with the WWL-1, while the WWL-C will work over the full zoom range of the 24-50mm.

I had not even thought about looking at the magnification differences. Being dense, I guess. Thank you for the explanation.