I use Simple DoF. Its quite easy to use all you have to do is to select your camera from a drop down list and then enter your aperture, focal length and focus distance. As an example if you enter f/2.8, 400 mm and 8 m the depth of field is 6.4 cm compared to 9.1 cm at f/4.0 (Canon 5D). How often do I use it, once in a blue moon. I think that if you know your limitations and that of your kit you can have more fun taking the images.