70-210 AF 4-5.6D Jumpy AF

[trevor_newman1]

Hello all,

 

I have been shooting a lot of rowing races with my F5 and 70-210 lately and I

noticed that whenever I go from focusing on something close to something far

away (or vice versa) in single servo mode the front element turns the opposite

direction for a split second before going the right way and locking focus. Focus

accuracy is not a problem, it is always dead on but it is kind of odd that it

almost consistently turns the wrong way first before going the right way. Is

this just a feature of the lens I am going to have to learn to live with or

should I get it checked out. It does this on both my F5 and my N90s so I don't

think it is the camera. Any comments would be greatly appreciated! Thank you much.

[Jerry_]

The camera is 'seeking' something of contrast to lock focus on. Once the image is in focus, you should be good to go. Rowing is not that quick-action of a sport to be concerned over (my guess.)

 

 

Your lens gets 'focusing speed' from the camera.

[robert_hooper1]

Yes, it sounds normal to me. That lens is pretty slow to begin with(f4-5.6), so shooting

in low light or low contrast situations the lens is going to hunt for focus. You might

consider getting a faster lens like the Nikon 80-200mm f2.8 AF which will focus quicker

than the lens you have, or better yet, a used version (its out of production) of the Nikon

80-200mm f2.8 AFS which will focus really fast.

[lex_jenkins]

"Chatter" is normal with many AF Nikkors. Hunting occurs more often with slower, variable aperture zooms. Felt "chatter" and vibration is more noticeable with telephotos and zooms due to the larger moving mass of the optical elements. The "screwdriver" focus lenses transmit quite a bit of felt chatter.

 

But all lenses, including wide angles and AF-S types, also hunt and chatter. We just don't feel it with the lower moving mass and don't notice it with AF-S lenses because they focus more quickly.

 

The best way to illustrate this for yourself is to compare the 80-200/2.8D AF Nikkor and 70-200/2.8 VR AF-S Nikkor side by side. In dim lighting, especially when panning around while autofocusing on objects ranging from minimum focus distance to around 10 feet way, you'll feel a significant amount of chatter in the 80-200/2.8 AF. The 70-200 VR is doing the same thing, but it's barely felt and happens much more quickly due to the SWM.

[nsfbr]

Hmm, I thought it was the fact that my old one doesn't have a "D". But, I guess not, because my 70-210 will sometimes do that as well.

 

It is still one hella sharp lens though. Best $150 lens (used) I ever bought.