A little AI to brighten my day!

AI? Not artificial intelligence, but automatic indexing instead.

One of the reasons I love Nikon is found in their apparent passion for forward compatibly. In 1959 Nikon released the F Mount lens when it released its F camera. This completely changed the landscape of professional photography. Prior to 1959 the SLR concept was young and the other available options were much more expensive and did not have the array of accessories. Nikon launched the F model with interchangeable options. It was enormously successful.

The next major innovation in lens mounting for Nikon came in 1977 when it added Automatic Indexing to its lenses. This enabled faster lens mounting and the ability for the camera to ‘know’ where the aperture was set with out cycling the aperture ring to it’s fullest extents. Nikon called these lenses AI since the indexing of the aperture was now quick and automatic. The actual mounting portion of the lens remained unchanged, and pre-AI lenses could be converted to AI with kits that Nikon made. To ensure customer satisfaction Nikon even did these conversions at the factory for a paltry $20 from 1977 to the mid 1980’s. This makes all those vintage lenses work with every Nikon SLR or DSLR camera to this very day.

Nikon’s professional grade cameras and the new D7000 camera all have the metering tab that reads the AI lenses. Less expensive models did not have this feature and work with all lenses since 1959 without issue, but these model cameras cannot know what the aperture setting is on the lens. This was true of my first Nikon D40. I came across a 1973 Nikkor 400mm f/5.6 lens last year on Craigslist for a steal of a price. It was owned by a doctor who had taken immaculate care of it, simply pristine. Until I purchased my D7000 I was not concerned about the non-AI design. It was then I learned all about these conversions, and what it really meant.

This kicked off an extensive search to find someone who converted these old lenses still. I found a few small groups that do a mechanical cutting of the original lens parts to make it work correctly. I learned that this ruins the collectible value of the lens but would make it usable. I was really torn, what I really wanted was one of those Nikon factory conversions done on my lens. The problem was I was 25 years too late to that party. I found that a few small companies had purchased Nikon’s remaining conversion kits back in the 80’s. I found 2 still offering inventory, one in Europe and one in the US. The group in Europe did not have any further kits fitting my lens. I was able to connect with a gentlemen in Nevada that had the one of the few remaining cache of these parts in the US. He checked his inventory and had ONE remaining, and he said it was probably the last on Earth new in a box.

I sent my lens to Nevada and he benched it and did the conversion. It returned home today. I cannot share how happy I am to have it back. If you have been reading my blog long, you know how much I used this 400mm lens in my shots, and now I can have assurance it won’t damage my camera, and it will meter correctly.

I was naturally itching to get a shot with my newly AI-Converted lens. The weather was not cooperating, the skies were gloomy and it was getting late in the evening when I was out shooting. I mounted up my flash and cranked it to 1/1 and went hunting. I was hand-holding the lens, so I needed speed to keep down motion blur from shotting free hand. The flash helped tremendously and I ran up the ISO a bit to give me the edge I needed. This male cardinal was sitting atop my 2nd story roof chirping for some attention from the ladies.

camera :: Nikon D7000 | 1/500′s second shutter | ISO 1000 | Meter: Spot | Exposure Comp +0.3
lens :: Nikkor 400mm | set at f/5.6 | Manual Focus
flash :: Promaster 7500EDF | Full Power


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