Set your camera to Aperture Priority mode (A or Av on the program dial). Select the smallest possible aperture (f) number for your lens (should be ≤f/4). Switch your camera to manual focus and manually adjust the focus to the closest setting. Zoom your lens to somewhere around 50mm. Find some nice points of light at a distance of 10′ or greater from the camera (your Christmas tree is the perfect subject this time of year). Fire away!
Select the smallest possible aperture (f) number for your lens (should be ≤f/4).
Switch your camera to manual focus and manually adjust the focus to the closest setting.
Zoom your lens to somewhere around 50mm.
Find some nice points of light at a distance of 10′ or greater from the camera (your Christmas tree is the perfect subject this time of year).
Fire away!