Dallmeyer lenses (named after the optician John Henry Dallmeyer) are rare and some have a very high collector's value. Dallmeyer was a significant lens manufacturer in the 19th and early 20th centuries.

Lenses are typically brand-specific, with each camera manufacturer using different mounts. This means that a lens from one brand often won't fit on a camera from another without the use of adapters. However, even with adapters, there can be limitations in lens functionality.