Is the voigtl nder septon 40mm f 2 aspherical good in low light?

The Septon is a reasonable choice in dim light, but it isn't a low-light lens. Its f/2 aperture lets in far more light than a typical kit zoom, which is the main reason primes are the better pick for this.

It's manual focus only, which is slow in dim scenes, and it has no stabilisation, so you'll need a shutter speed you can hold by hand, or a camera with stabilisation built in.

If low light is the main job, the Voigtländer Nokton 40mm f/1.2 Aspherical is a full frame 40mm with a much wider aperture. Full frame also helps on its own, since a bigger sensor collects more light than APS-C at the same settings.

Written by Claude from this site's pages.