What are the issues when using film camera lenses for digital?

Leica and Nikon digital camera bodies can accept their older lenses. Great, but what are the results and issues for the images taken? Do we need to be concerned about aberrations, etc?

Pentax and Nikon have the greatest backwards compatibility and some very old lenses can be used.

Reduced size sensors are advantageous in that only the centre of the lens's field is used, but equally well chromatic aberrations may not be so closely controlled as they are these days.

Very old lenses can be fine on digital, older zooms will probably not be as good as current ones.

In the case of Pentax any AF lens, and any "A" series manual focus lens, will perform well and with full function but older kit zooms may only be adequate.

It's a case-by-case situation and it's worth being a member of a forum that specialises in whatever marque you use. There you will find specific information.

John