Nikkor 135mm f/2.8 (all versions)

General
In my continuous search for cheap but good lenses, I try plenty of older, manual focus lenses. They are usually quite cheap (depending of course), and still they offer very high quality - both in terms of optical performance and in terms of construction quality. The 135mm f/2.8 is such a lens. The lens I tried recently was the AI-S variety, but even the older, AI and pre-AI versions (which I have also tested) aren't far behind either.

Pros/Cons
+ great value. The pre-AI is less than $100, the AI-S ~$150. It's worth at least that much, and more.
+ even in absolute terms, optical quality is on very high levels. Very good wide-open, excellent beyond that.
+ built like a tank. It will outlive your camera. Maybe even you.

- manual-focus
- the older, pre-AI had a tiny loss of contrast wide-open. Irrelevant for portraiture.
- the pre-AI can't be used with all digital Nikons. Double-check compatibility to avoid breaking your camera!

Even wide-open, it performs very well.

Intended Users
Great for:

• FX users who need a cheap but capable portrait lens
• low-light candids (provided you have working room; this is not an indoor lens)
• As a sports tele in low(er) light, it can be a budget solution, but manual focus will force you to work a lot on your discipline and technique - which, hey, it's not such a bad thing!

Not for:

• entry level cameras. Manual focus is OK, loss of exposure metering is more of an issue
• moving subjects can also be a problem in terms of there not being autofocus
• Skip for DX in general. Too long to make sense as a portrait lens (unless if there is ample space outdoors).

Closed-down a stop, it's flawless really.

Final Verdict
An outstanding 'little' lens. Small and light, very well-made, delivering stellar optical quality. Exactly as lenses should be made. What you give away? The comfort of autofocus, obviously, and...that's about it. If primes are your thing, this is a great portrait or short tele lens. It makes more sense on FX, but of course some DX users might also find use for it.