SkipD wrote in post #16654979
What do you mean by "bulb design"? I've never heard that term applied to photographic lenses.
I believe the OP will need to give us a specific radius, as the term most likely has no meaning otherwise.
The front element of most lenses, and certainly all wide angle lenses is noticeably curved. If such a front element has a very small radius relative to other lenses, that front element will appear to be 'bulbous' in layterms.
But since all front elements (pretty much) are curved, there is of course no defined radius below which an element's front element is specifically 'bulb design'.
Probably more importantly, there is no relationship between the radius of the front element and the lens flare performance.
What I think the OP should focus on in looking at wide angle lenses:
1) If the front element is compatible with the use of screw in filters or not. This is the main point where a bulbous front element can be a hassle.
2) How the lens performs for flare. And looking at the shape of the front element is a terrible way to assess flare performance. Flare is a function of the overall lens design including number of elements, coatings, internal reflections etc.
