Is the leica apo summicron sl 28mm f 2 asph good in low light?

This lens is a good choice for low light. Its f/2 maximum aperture lets in plenty of light. I don't have test results for its high-ISO performance, though, so this is a reasoned answer, not a measured one. It isn't stabilised, so in dim rooms you'll need a faster shutter speed or a body with stabilisation built in.

The camera matters as much as the lens. A full-frame body gives you roughly a stop more clean high-ISO performance than APS-C, so the Leica SL3-S or the Panasonic Lumix S5 II will make the most of it. The Leica TL2 also takes this lens, but it frames it at about 42mm and gives you less light to work with.

For the reasoning behind this, see Sensor sizes.

Written by Claude from this site's pages.