What's the difference between a SLR Lens, a metal bayonet and a plastic bayonet? Are there any differences in the imaging?
Metal bayonet lens, relative to plastic bayonet lens, the service life may be longer, professional lenses are metal bayonet.
Plastic bayonet lenses are generally inexpensive entry level lenses;
The bayonet itself has no effect on the image, but the life of the plastic bayonet is short. It is only used in the low-end entry lens, and the good middle and high lens of the image will not use plastic and all the metal bayonet.