Is the leica apo summicron sl 50mm f 2 asph good in low light?

Here is what the site says about that.

From Leica APO-Summicron-SL 50mm f/2 ASPH: Leica APO-Summicron-SL 50mm f/2 ASPH: A prime lens by Leica for Full frame cameras, 50mm f/2. Specs - Maker: Leica - Focal length: 50mm (prime) - Maximum aperture: f/2 - Made for: Full frame sensors - Mounts: L-Mount - Stabilised: no - Autofocus: yes What it frames like - On full frame (L-Mount): as marked, 50mm. - On APS-C (L-Mount): like 75mm on full frame; f/2 gives about the depth of field of f/3 there. ...

From Leica Summicron-SL 50mm f/2 ASPH: Leica Summicron-SL 50mm f/2 ASPH: A prime lens by Leica for Full frame cameras, 50mm f/2. About half the weight of the APO-Summicron-SL 50.

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