This is going to sound really rude but...
YOUR RIGHT IT'S TERRIBLE! For Depth of field at least.
Now that is over and done with I will focus on Depth in an Image.
So I took the image and butchered it to illustrate my point.
I do not have the original PSD, this has been a 10 minute chop from the JPG image.
The content changes in the image are designed to pull the eyes to the foreground and create artificial depth.
- Shadows: Shadows are really important, not just cast shadows but also self shadowing.
- Highlights: are just as important as shadowing, again not just self highlighting but also cast light.
(Light doesn't just illuminate everything, if you have too much ambient light, the image will look flat and without body, like having a flash on a camera.
- Blur: A subtle blend of blur at different levels of intensity in your image will alter the entire feeling of the image.
Paint Brush tool. (For painting new shadows on the ground and objects)
Blur Tool (For creating a layered depth of field
Burn tool (For intensifying existing shadows)
Dodge tool (For increasing highlights.
Overlaid layers to up the flat contrast.
The result is a mix of shadows that cross the image and a subtle yet intense blur that actually pulls the eye to a constructed foreground. The mere fact that it does this means the effect has been successful. It now has a depth of field...
10 minutes is not my best work but it will suffice.