35mm SLRs and Electronic Flash (MM404)

For this week's mono Monday on the theme of 20th Century inventions I have gone for some of the significant developments in photography.

35mm films in cassettes were introduced in the mid 1930s,  the SLR came in ~1949 and the electronic flash in the early 70s. 

I suppose with the economics of the 70s and 80s meaning that more of us (in the West?) could afford to buy this sort of thing,  progress became faster too?

The Pentax is loaded with Ilford Pan F (50 iso)
The Canon with Ilford Delta (400 iso)
Both still work although the Pentax is much quieter, and we've owned it from new in ~1982(ish)
The Canon was £10 in a camera club bring & buy sale.

A nod to modernity in the Peak Design strap connectors and 3LT tripod plate.

Thanks to Laurie54 for hosting.