Guys,
thanks for the Kingslake reference! I just looked up on the library website of our university... they have it available, between other books:
A history of the photographic lens Rudolf Kingslake 1989;
Optical system design Rudolf Kingslake 1983;
Lens design fundamentals Rudolf Kingslake 1978;
Light : its generation and modification Rudolf Kingslake 1965;
Lenses in photography : the practical guide to optics for photographers Rudolf Kingslake 1963;
Applied optics and optical design A.E. Conrady 1957-1960;
Applied optics and optical engineering Rudolf Kingslake 1965
they jave them all available except the second one, which is out at somebody.
I think i'll take a walk to check them out! it's at five minutes distance... i love working at an university!
If i find stg interesting, i'll keep you informed.