100-400/5.6 autofocus trouble

[jpbeale]

I borrowed a friend's 100-400/5.6L IS lens to try on my D30. The zoom is impressive but the autofocus seems unusable. With the AF range-limiting switch at the more distant setting, the focus would "chatter" back and forth continuously at 400mm focal length with about half the subjects I tried, even outdoors at noon on a cloudy-bright day and with high contrast subjects (black tree limbs against the sky). With the other setting of the range-limiter it doesn't focus at all beyond about 200 mm.

Has anyone used this lens sucessfully at 400mm with autofocus? Manual focus could work, but is pretty hard with flying birds, which is the reason I'd want to use this lens.

[Roger_Cavanagh]

Your friend's lens sounds as if it is performing much worse than mine. I have no trouble in the circumstances you describe. Did you have the central focus point selected?

Mind you, it's pretty hard to hit those birds in flight _and_ in focus whatever the circumstances. :)

Regards,

Roger
www.rogercavanagh.com

[ErnieE]

I get the chatter effect on ALL of my L series glass with the D30 under certain circumstances. I basically chalked it up to YET ANOTHER annoying thing about the D30. The same glass on an EOS-3 performs without a problem. I figured it has something to do with the crappy AF system (compared to the EOS3 or 1V) and just lived with it.

The chatter ONLY happens for me at infinity under a few light conditions.

I figured that the 1D would fix this problem. :)

[jpbeale]

To follow up my original post, trying the same lens this evening indoors with office-type flourescent lighting overhead, the lens focused very well! This was light so dim that the exposure was f/4.5, 1/10 sec at ASA 400. Mysterious, maybe I did have the focusing points mis-set earlier (normally I use center point only). The IS feature is truly impressive, I hand-held the lens at 200 mm at 1/10 sec and got a fairly decent image.

[atosheff]

I get the chatter too on my brand-new 100-400 IS USM and the D30 - especially at 400mm. I will be playing around to try to baseline this behavior and will post results asap...

Alex

[jpbeale]

I wandered out into the parking lot at lunch and a hawk obligingly flew overhead. http://www.bealecorner.net/D30/010902/hawk01.jpg

Shot data: D30 with 100-400/5.6 at 400mm, ASA100, 1/500 s, f6.7, IS mode 2. The sky was around 50% so the hawk was very underexposed- I brightened, sharpened, and cropped to about 20% of the full frame in photoshop.

The autofocus works sometimes, but chatters back and forth a lot- it seems like a servo loop with the gain turned too high, to me. Oddly, it doesn't chatter so much in dim light.

[Wayne Booth]

After ready this thread I got my 100-400 IS out and gave it a try because I don't remember having this problem. Results: no problem! It is a bright day and everything focused in quickly ( I was doing all this at 400mm mode 2). Tried again with mode 1 and did get a "little" clatter but nothing serious and focus was pretty darn quick.

[roine]

Hello

I also have the 100-400 IS, and have no problem.

What version of the firmware in the camera do You use?

Following several forums, there seems to bee some difference in the two latest releases.

Ver. 1.0.2.0 and a off record release Ver. 1.0.2.2 seems a bit faster and better than the originally firmware.

Roine

[atosheff]

Well - I took my camera out and played with the different setting on the lens - the chatter really only happens at 400 and in bright sunlight, but I noticed when I turned the Servo AI focus off it stopped!

alex