Just how good is the Leica 50mm f/0.95 Noctilux-M ASPH? It’s one of the world’s most expensive lenses that can be bought at a store, if you can find one in stock (if one does show up in stock, thanks for using the link from this site!). Leica reportedly can produce only twelve copies a day, and they are not made every day.
The Noctilux uses exotic types of optical glass, as well as an two aspheric elements. Five of the eight elements are “anomalous partial dispersion”, three of those have high refractive power, and the two aspheric elements are ground and polished mechanically, a very expensive and time-consuming process. Reportedly, one of the elements must be coated within 20 minutes or it will oxidize. Not exactly a simple lens to build, hence the high cost.
I have to chuckle when I get the occasional email complaint about purple fringing wide open with some Zeiss f/1.4 and f/2 lenses. If Leica can’t eliminate purple fringing for US$10,495, I guess that’s the way it is. See picture below and that’s the entire frame, not a crop. Purple fringing is also due in good measure to the sensor/camera, not the lens alone. The M9 sensor is very prone to it.