markhamwong

SIGMA的18-200mm也有3个版本，第一支是普通的，第二支是带有“OS”防抖的，第三支是带“OS”还带“HSM”超声波的，一支比一支好，尤其是第三支带“OS HSM”的.
你用哪一支呢？有多老？你有沒有將其發送回simga維修(對齊alignment)

markhamwong

3# kg87 try reset a  to factory default settings (D7000)Two Button reset
simply holding two buttons simultaneously for two seconds (both buttons are marked with a green dot for reference). QUAL (image quality/Size) and +/- Exposure Compensation button.

markhamwong

Do you have other lens to try?

markhamwong

Did you forgot to turn off Manual Focus from your D7000 body?
Choose how the focus point for autofocus is selected.
• Single-point AF: Select the focus point as described on page 96; the camera will focus
on the subject in the selected focus point only. Use with stationary subjects.
• Dynamic-area AF: Select the focus point as described on page 96. In AF-A and AF-C
focus modes, the camera will focus based on information from surrounding focus
points if the subject briefly leaves the selected point. The number of focus points
varies with the mode selected:
- 9-point dynamic-area AF: Choose when there is time to compose the photograph or
when photographing subjects that are moving predictably (e.g., runners or race
cars on a track).
- 21-point dynamic-area AF: Choose when photographing subjects that are moving
unpredictably (e.g., players at a football game).
- 39-point dynamic-area AF: Choose when photographing subjects that are moving
quickly and can not be easily framed in the viewfinder (e.g., birds).
• 3D-tracking: Select the focus point as described on page 96. In AF-A and AF-C focus
modes, the camera will track subjects that leave the selected focus point and select
new focus points as required. Use to quickly compose pictures with subjects that
are moving erratically from side to side (e.g., tennis players). If the subject leaves
viewfinder, remove your finger from the shutter-release button and recompose
the photograph with the subject in the selected focus point.