a strange thing happened to my lens suddenly yesterday when i was out. I attatched the lens to the camera, and tried to take a pic at 55mm.... the viewfinder was darker than normal, and the camera couldnt focus, but when i zoomed out to about 45mm, the viewfinder brightened up back to normal, and the focus worked perfectly, but when i'd zoom back to 55mm, the same thing would happen....my guess is something with the aperture, because when i remove the lens from the camera, and turned the zoom ring, it would catch, but if i hold the aperture lever (which attaches to the camera) the lens moved freely.

also if it helps, when i use the auto setting, and i try to take a pic at 55mm, the shutter slows way down to 1/20 or so, and the flash opens and the focus light comes on.

this just happened abruptly, and i was wondering if anyone had any input

it is the lens that came with my Nikon D40

much appreciated,
jer

I vaguely recall reading about that problem before, but can't remember what causes it. I too have had this happen recently with two zoom lenses I inherited for my Canon. Suddenly, at certain distances, nothing happens in autofocus, change shutter speed and it works.

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The railfan side

My pictures

Is there a depth of field preview switch, or function?
With the dark viewfinder and slow shutter speed, it sounds like the lens may be stopped down to f 22 or smaller and the preview is on.

Just a thought, I'm a Canon guy, but it sounds like something I've seen before

Dave Burman
former photo guy/teacher

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Dave Burman
Modeling the Modern Twin Cities

The autofocus miss/no function thing on the Canon's is likely not getting the Ultrasonic pulse return to the sensor in the view finder. It'll do that when its stopped down on a bright day. Some lenses can stick as well(dirty contacts on the back of EOS lenses are notorius for this). if you send the focus point at a dark object, sometimes the focus will swim due to the same thing

Early Canon's needed f 5.6 or wider to get AF locks. The camera stops down when you press the shutter for picture. a light press causes actuation of focus without activating the stop down to get the aperature. Later sensors could work at f8 or wider This helped 2x extenders work better on canon AF lenses

Probably way more than you wanted to know......

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Dave Burman
Modeling the Modern Twin Cities