Lens technology....

[Flash In The Pan]

it's moved on a bit since the 1950s

As the front element (from the lens of my Ihagee EXA IIa,above) shows

 

[Barlines]

I had to study that a bit - it looks like the lens from a pair of glasses I once owned :shake:

 

[Flash In The Pan]

I had to study that a bit - it looks like the lens from a pair of glasses I once owned :shake:

Did you end up cutting a marble in half and making a pair of contact lenses?