or you can do this:
1. Create a solid layer on top of your image(keyboard shortcut- ctrl-Y)
2. Make your solid layer opacity to 50 percent
3. click the Q several times to choose the elliptical mask. Assuming you solid layer is selected, drag it across the viewer window with while click holding the shift key to create a perfect circle. Don’t overdo it & keep the elliptical mask whre you can view it at 100 percent.
4. Click the aspostrophe key(or the key beside the semicolon key,to the right) to activate the Action safe in your viewer. When activated, you can use the crosshair at the center a a reference.
5. Double click your mask, now your mask will have a crosshair at its center.
6. Position your mask in the middle of the viewer aligning its crosshair to the crosshair of the action safe.
7. Now drag your image to properly place it in the middle of the viewer using the solid layer as reference. scale your image to properly fit the size of the solid layer & properly aligning it to the solid layer.
8. Now click Y in your keyboard. Notice the selection tool(or your cursor) changes its appearance(basically your selection tool with a circle attached to it). It’s now the Pan Behind Tool.Its a tool for repositioning the anchor point without changing the position properties.
When doing so, notice a red chrosshair appears in the viewer. Using the Pan Behind Tool, select & drag the red crosshair in the middle of the viewer using the crosshair of the action safe as guide.
9. Click V to change the tool back to Selection Tool. Now you have your proper ancor point on you image.
Hope it helps.