(CLICK FOR FULL-RES)
When you first open the Gallery in Iris Blur mode, you’ll see an oval of sharpness in the middle. Grab it by its center to place it. To adjust the blur level, move the slider in the toolbar or grab and move the circular slider in the center of the floating blur tool. As you adjust, you’ll see a heads-up display showing you the level of blur. You can always go back and modify it using either method.