A friend of mine has a similar problem with AF hunting and lack of sharpness for his Tamron zoom on the F-100. His Nikon lenss work great. His camera store said that they can make some adjustment to the Tamron lens. George ------------------------------------ I'm suffering from the same problem. I bought my F100 last January here in Switzerland. When using a Sigma 70-300mm and focussing at 70mm, the subject is not sharp when zooming to 300mm. If I focus at 300mm (the subject is now sharp) and I zoom back to 70 and focus again, the camera re-focuses and the subject become unsharp again. This is exactly conform the article in the latest issue of Chasseur d'Images. By the way, the problem doesn't occur when using my Nikon 35-105mm. It looks like a bug to me and I reported it to the Nikon Service. Regards, Toine