One of the bonuses of babysitting my brother's camera equipment while he and his family moves house is I get to play with some really cool toys. In this case a Leicaflex Sl, Leitz's answer to the Japanese SLR juggernaut in the 1960's, alas for them, loo little, too late.
That being said Leica SLR lenses are really nice glass and it's a shame they never made them in third party mount for example Nikon F, Pentax K mount, etc.
In this particular set, I went out on a damp Sunday morning with a black Leicaflex SL and got a chance to put a 21 F4 Super Angulon through it's paces along with the 35 f2 R Summicron that I used as the prime lens on the camera. The film used was Fuji Pro 160 S rated at 100 ISO.