Nikon AI Lens Conversions: A Bit of History
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This post is about Nikon AI lens conversions:
Many years ago before I specialized in Mamiya cameras, I serviced many of the popular Japanese brands and of course Nikon was a popular camera manufacturer. When Nikon introduced the AI lens mount in 1977, they offered a conversion on earlier non AI lenses. The conversion kits were not made available to independent repair shops so customers needed to send their lenses to Nikon USA.
Sometime in the late 1980’s I was at Nikon’s new facility in Torrance, CA and had the opportunity to speak to the National Part Manager, Harry Papian. I asked him why Nikon was not providing repair shops with the AI conversion kits. He thought for a moment and then said that he would change the policy and allow sales of the AI kits. As soon as I returned to my shop, I began ordering AI kits from Nikon (there were around ninety different kits for the various lenses) and started providing conversion service. I did about five hundred conversions until Nikon’s supply ran dry.
End of the year and I am doing chores like removing the AI prongs from rings of conversions that I did many years ago as seen in photo one. While the prongs may seem the same, photo two shows my parts box of new prongs and there are at least eleven varieties. The various lenses had different diameters and thickness of aperture rings so the prongs were slightly different to keep the distance from the center of the slot to the inner ring surface to around 5mm. As seen in the photos, the difference in prongs can be very subtle.
