Just measurebating I guess, but remember that the 10.5 should be less affected by a small dome than a zoom
Definitely. Wider reclinear glass works better with dome glass matching the field of view.
Much like the glass vs PC debate, there has been no evidence provided that Glass is better than PC, or that a larger dome is sharper than a smaller dome.
I think glass vs. PC debate is meaningless as a general discussion which is better.
From my understanding:
+ better contrast
+ more resistant against flare / reflections
+ more resistant against scratches
- if scratched, more difficult to polish
- refraction index differs from water
- easily scratched
+ more easy to remove scratches
+ refraction index more close to water
- less resistant against flare/reflections
I want to add that UK-Germany,Sealux and Subal put fisheyes behind dome glass with less than 180° coverage as well (and the curvature centre doesn't meet the entrance pupil). Fisheyes are not that critical as super wideangles (see point above). But the glass is still big enough for split shots and maintaing a certain radius. This is where the 8" Dome comes in from Ikelite. And for super wideangles it provides the appropiate coverage allowing the usage of the full radius.