This lens is a good compromise for Leica M users who want a 'standard' lens that is fast, has very respectable performance and is not too bulky.

The 50mm f/1.4 Summilux-M lens is sometimes regarded, within Leica circles, as sligthtly inferior to other current Leica M lenses, on account of its old design. Its optical formula that hasn't changed substantially since the 1960s. There is speculation that Leica may one day upgrade it, as happened recently with the 50mm f/1.4 Summilux-R, which is now an excellent performer in all respects. However, it is still generally agreed that the 50mm f/1.4 Summilux-M remains one of the very best 50mm f/1.4 lenses on the market.

Performance of this lens is very good even wide open, a strength in general of Leica lenses, and is improved further by stopping down by 2 or 3 stops. It has excellent color rendering and contrast; the control of coma and flare are also very good. Vignetting is noticeable at f/1.4 and f/2 but in low light that is often not a problem; it disappears by f/4. There is no distortion.

The 50 Summilux is quite a compact lens, with a weight of 275 grams (black) or 380 grams (chrome), a length of 46.7 mm and a width of 54.5 mm. The current version can focus as close as 70cm and has a built-in retractable hood. Previous versions had minimum focus of 1 meter and a detachable hood.

The 50 Summilux is one stop slower than the much bigger, heavier and more expensive 50mm f/1 Noctilux, which weighs in at 630 grams, is 62 mm long and 69 mm wide. The performance of the Summilux is about the same as the Noctilux at all stops the two lenses have in common (f/1.4 to f/16). The 50 Summilux is one stop faster than the slightly smaller and much cheaper Summicron. Its optical performance is not quite up to the standard of the Summicron at apertures wider than f/5.6 but is very good nevertheless.

As with most Leica glass, the biggest drawback of the 50mm f/1.4 Summilux is
its price. It retails for about $1,800 compared with "only" $950 for the 50mm f/2 Summicron. That's a lot of extra money for only one f-stop! On the other hand, the 50mm f/1 Noctilux is about $2,600 but that is a very special lens.

There are some good used examples to be had on the market for about half the price of a new lens and previous versions are available for even less. Grey market is another option for economizing, offering savings of about 20% of the official retail price.