Nikkor ED AF-I 600 mm f/4 D

[Tersn]

I wonder how slow the AF-I is. Is it too slow for action ? Suppose its weight is 5 kg or so?. There is an offer of one at  about $3000  (NKr 25.000)  presently.

[PedroS]

I have used a lot until I got my 600VR, a 800 AI-S.
For action (just used for BIF, but it's the same), I mainly used two tricks:
One was only shooting when in focus (you can program your camera like that). So to catch the birds I just clicked down continuously and turned the focus ring until it starts to shoot. Then continue to turn left/right the focus ring always following the bird;
The other one was trying to guess the distance and click, click...
Either way, you have to be prepared to accept a low percentage of good photos...

Ah, a sturdy tripod is always a plus!!

[Akira]

Terje, you should make sure that you can have the AF motor replaced, if it would fail.  AF-I motor is a rare part.

[Bjørn Rørslett]

I would advise against buying any of the AF-I lenses at the moment. They are getting old and while the optics still are good to excellent, motor failure is quite likely to happen in the life span of the lens and spare parts are tricky to source if they at all can be found.

[Tersn]

Thanks for your inputs, guys. Guess I will go for a newer version with AF-S, or perhaps the new 500mm f/4 FL that should even be handholdable (at 3.09 kg).

[Roland Vink]

If the motor gives out, you still have an excellent (but heavy) manual focus AI-P lens

[Erik Lund]

the old AF-I lenses focused about as fast as AFS just with a little more sound...

As long as the AF-I motor works it works So if you can get it cheap it's a super nice lens

[Tersn]

If the motor gives out, you still have an excellent (but heavy) manual focus AI-P lens

Certainly, but I don't really need a manual focus 600mm lens.

the old AF-I lenses focused about as fast as AFS just with a little more sound...

As long as the AF-I motor works it works So if you can get it cheap it's a super nice lens

Yes, but when the motor stops working (which seems likely  to happen rather soon after all these years), I am left with a MF lens that I don't really need and that will be hard to sell.

[Erik Lund]

If the motor was likely to fail the marked would be flooded with old AF-I MF lenses... and the prices would drop...

[Bjørn Rørslett]

People might keep the lens as it lost much of its sales value ...

I have been contact a number of times by people asking for help with dead AFI motors.  So yes, it happens. I have no statistical valid estimate of the risk level of course, but it is pertinent to point out that spare parts no longer are available. Thus Nikon's own estimate of motor longevity must be off.