Aperturepedia collects data on various vintage first-party SLR lenses in one easy-to-reference site.
The goal here is to provide a free resource with long-term support for referencing and comparing specs for most vintage first-party camera lenses, as well as a repository for helpful links to other sites which may not immediately come up in Google, or Wayback Machine-cached dead sites (RIP Geocities). Those of you who are seeking to break into adapting vintage glass on your mirrorless camera or expand your legacy lens collection can find easy-to-parse comparison charts for the lens systems listed below.
It's very much a work in progress, and any feedback on features or enhancements are welcome. The contact email address is this website's name at gmail dot com. (This hint is an effort to minimize spam)
Aperturepedia itself was built by Nick Klein, with data aggregated from a number of online resources. In addition to listing these resources on each lens system's "Links" page, here's a short list of sites which were especially instrumental in the success of this site.