The truth in lens diagrams

[Blazer0ne]

...

[Oldhand]

I don't see very much difference between the lens and the diagram - the concave surfaces both look about the same as the picture.
Tom

[Lightshow]

The non optical surfaces can and do change to make manufacture of the lens easier, those surfaces are not critical, they aren't described in patents, the drawing may come from a patent of a prototype, the production lens could be different to aid in assembly, but those curved optical surfaces should be accurately drawn.

[visualopsins]

Well that mystical element very well could and probably does make those ringed bubbles with those perpendicular edges! Maybe not a complete untruth giving the correct curvatures but blurring the (secret, patented?) edge construction detail which probably does produce those bubbles. I think you've found it!

[kds315*]

Naaaaa, this is just made to mount it better/easier. And certainly has NOTHING to do with the two-focal lens (predecessor of aspheric lens)...

[Alex TG]

First of all, bubble bokeh is just the result of overcorrected spherical aberration, and it is a function of the whole lens, not some mystical single element.
Second, side surfaces of the elements indeed have virtually no effect on image, especially when the lens is stopped down.
Third, optical diagrams are quite approximate - they only show types of curvature of both sides of lens elements (flat, concave or convex) and relative sizes of the elements to avoid confusion between them.

[Blazer0ne]

...

[visualopsins]

Conclusive? (#1image) Sure other lenses have bubble oof highlights but not with the ring as we see with this lens. I was joking about the purpose of the shelf is to produce the ring -- the engineers were probably horrified at their design mistake until they discovered people really like it!

[visualopsins]

PS Lots can be see in oof highlights, the entire inside of any lens! Try with holiday lights oof enough to get oof bubbles. Compare inside of bubbles with shining lamp through back of lens to see inside of lens dust,, element defects, fungii etc....

[Blazer0ne]

...