The following article on creating depth of field using photoshop was submitted by Big Bouquet Photography.from
If you didn’t quite get your aperture settings right when you were out and about with your camera it’s possible to recreate a depth of field effect in Photoshop.
Similarly if you want to heighten the either of depth of field in your photography you can use Photoshop to do that too. Depth of field allows you to draw attention to an element in your photograph.
With some quick tweaks to your image’s sharpness using Photoshop’s filters and Layer Masking you can easily recreate the look of a small depth of field.
Here’s how you do it in 7 Simple Steps (click to enlarge images):
1. Copy your layer
Open up an image that would suit a depth of field look (close-up shots work best for this as you will be able to isolate elements in the foreground easily from the background). Open up your Layers Palette and drag the Background Layer onto the icon at the bottom of the Layers Palette called ‘Create a new Layer’. This will make a copy layer of your image.
2. Gaussian blur
Make sure that your ‘Background Copy’ layer is still selected and then choose the following from the upper toolbar: Filter>Blur>Gaussian Blur.
3. Your blur settings
In reality, the blur in an image that had strong depth of field wouldn’t be as much as the blur that shows from the default Gaussian Blur settings. So, using the slider controls take the blur amount down to a Radius of 8.5 pixels. Then, press OK.
4. Masking out
Now here’s where we can set the areas that will remain in sharp focus to give us our depth of field effect. With the ‘Background copy’ layer still selected add a Layer Mask by clicking on the ‘Add Layer Mask’ icon at the bottom of the layers palette (this looks like a circle in a rectangle). A white rectangle will appear in your ‘Background Copy’ layer.
5. Applying your mask
Masking is a really good technique to master in Photoshop. It will allow you to reveal more or less of the layer underneath and it’s a much better technique to use than the Eraser Tool as it’s completely reversible. You apply a Layer Mask using the Brush Tool with a Soft Brush selected. Using a black colour will reveal the image underneath (in this case our sharp version of the flowers), whereas a white colour will erase any unwanted applied masking. With your Layer Mask thumbnail still selected use a black brush to paint over the areas you want to be sharp.
TIP: If you want to move around your canvas easily without using the scroll bars, you can hold down your Space bar and drag the canvas with your left-mouse button or your graphics pen.
6. Reversing your mask
If you think that you have applied too much Layer Masking as you’re going along, it’s easy enough to paint out your mask with a white Brush. Simply change the colour in your foreground palette to white and paint over it again.
7. Subtle masking
If you want to blend together your sharp elements with your blurred areas to make the transition look convincing you can apply a grey layer mask. Change your foreground palette to grey and then brush over the elements that you think would still be in relative focus. Remember to zoom out now and again so you can judge how successful your masking looks. When you’re happy flatten your layers by choosing Layer>Flatten Image and Save.
TIP: When you are applying your mask make sure you zoom in enough to be able to see all of your details for accurate painting. You can get around awkward spaces by altering the size of your brush. The easiest way to do this without breaking your concentration is by pressing the ‘[‘ and ‘]’ keys on your keyboard to make your brush smaller and larger.