Sigma APO Teleconverter 1.4X EX DG for Nikon F pentax adapter so you'll want to be

so you'll want to be sure that you choose the right tool for the job

The 40mm focal length makes it a versatile all-purpose prime

with light finish wear and approximately 2000 actuations

Compatible with Canon RF-mount lenses (not included)

1971 was 50 years ago

Sigma APO Teleconverter 1.4X EX DG for Nikon F pentax adapter so you'll want to beThe Sigma APO Teleconverter 1. 4X EX DG for Nikon F mount is a good quality, compact teleconverter for use with many (but not all!) Sigma F mount zoom lenses. It may also work with other brands, but we can't guarantee it. Please check your lens instruction manual for compatibility: this is not a universal teleconverter and it won't work with everything. In excellent condition, with clean glass and good function.