Most still lenses are not built with the same build quality as cinema lenses. This is especially true for modern lenses. Photographers nowadays rely heavily on autofocus, which means the manual focus control is not as precise. However, when manual focus was standard, as on older lenses, the focus ring was much more usable.
The nice thing about old lenses like the Nikkor AI and AI-S line is that they're no longer being made, so they are very inexpensive relative to lenses of similar quality. Find them on eBay, Amazon, at garage sales or on Craigslist. There are many things in addition to their inexpensive price tag to love about old Nikkors.
When filmmakers pick up and use these lenses, they usually note that they're built like tanks. According to Ken Rockwell, “Nikkor manual focus AI-s lenses... [are] built to the highest mechanical standards of any lens ever made.” This is true for the AI line as well, which are identical in optical and build quality.
The AI lenses have a slightly longer focus throw than AI-S lenses, but both lines have a much longer focus throw than any modern autofocus lens. Still not as good as cinema lenses, but this feature makes achieving sharp focus much easier. Also, most AI and AI-S lenses have a hard infinity focus stop, essential for most experienced focus pullers because it is much easier to rely on muscle memory.
Difference Between AI and AI-S
There is no real practical difference between the two lines, and Shane Hurlbut loves both: “they are the cream of the crop in the Nikon line.” Similar in optical quality, the main difference comes in focus throw; the AI-S series was designed for autofocus cameras and have a slightly shorter focus throw.
The drawback of these lenses is that they focus in the opposite direction to all other lenses, cinema or still. This can be a pain for seasoned focus pullers or Canon photographers but not an impossible switch. It is impractical to flip the focus direction in the lens, as this requires a complete rebuild of the focus mechanics, but follow focus systems sometimes have a switch that allows you to pull focus normally with the flip of the switch.
Another potential drawback in these lenses is you need to buy an adapter for each lens if you own a Canon body, or one adapter that you can place on each lens. When you use an adapter all internal automatic metering is lost. But often the money you save with these lenses justifies the purchase of a dedicated light meter and adapter.
Check these Lenses Out
If you're building your lens collection, it's probably a good idea to have a wide angle, a standard and a longer lens. These lenses will allow yout to take the majority of the shots you want. Prime lenses offer superior quality to zooms, though you'll sacrifice some convenience because you'll need to change the lenses out when you need a different focal length. Look for Nikon 24mm f/2.8 AIS, 50mm f/1.4 AIS and 105mm f/2.5 AIS at Amazon here and other retailers that sell used equipment to fit your needs for fast wide, standard and long lenses.