In general, good quality single focal length lenses from the 50's such as a Sonnar should not have that much more flare than current lenses. They were coated, and that's a very important factor. For the most part I would say the differences in low value contrast between a 1950s 50mm Sonnar and current Biogon could be compensated for in printing/scanning/processing. One way to help even things out even more would be to use a good lens shade with the older lenses and do your best to shield the front element from extraneous light, particularly bright light sources just outside the frame.
Originally Posted by puketronic