Updated: Oct 25, 2021
Can an adapted manual focus or rangefinder lens on my Camera reduce the Image Quality / Exposure etc. especially during low light conditions?
For example, many Sony Mirrorless or FujiFilm X series camera owners use Voigtländer M mount rangefinder lenses on their camera for superior image quality. The only downside to using an adapted lens is that the camera will have no way of recording the aperture value, lens make & model to the picture's EXIF data, meaning, you will have to manually apply lens correction settings (if at all needed) in Lightroom or other similar post processing software.
Software like Lightroom, Afinity, Capture One etc. all have Voigtländer lens profile and can be easily applied when processing pictures taken with them.
Modern cameras have both phase & contrast detection capabilities. The intelligence to assess the light conditions is well within the camera body & not on the lens hence it doesn’t really matter what lens was used to take the picture. As long as you can mount the lens on your camera & focus with it, you are all set! You can shoot in Aperture Priority or completely manual mode depending on what's your lighting condition and how you want to take your shots.