Shooting with 200mm f/2, 135mm f/1.8 and 105mm f/1.4 lenses is the dream of many portrait photographers. But such lenses are not inexpensive. We may only have a kit zoom that will never give us the look we really want. But, there are other options. Stop down for sharpness, then simulate that shallow depth of field in post. It won’t look quite the same as doing it optically, but it’ll can get you pretty close with a little effort.
In this video, Unmesh Dinda from Piximperfect shows us an easy way to simulate a shallow depth of field in Photoshop. The technique involves using a depth map. This tells various plugins how far away something is. This allows us to get that blur falling off as we get further from the camera. It allows you to get that soft blurry background in just three simple steps.
Even though the steps are simple, they are not quick, as evidenced by the fact that this tutorial is 20 minutes long. Of course, Unmesh is explaining it to us as he goes, which is naturally going to slow down the process. Doing it for yourself, more practise will speed up your workflow, and it will largely depend on the image you choose.
The first step is to create a selection of the subject. This is the most important step to get right. You need to have your selection be as close to perfect as possible. There’s no right or wrong way to do this, though. Just use whatever selection methods you’re used to. Then refine the edges to tweak things just a little and turn it into a mask.
After the mask is completed, we need to paint in the environment, to create a smooth transition between white to black along the ground. This is our depth map. We know that our subject sits sharply defined from the background, so we would expect to see a sharp transition from black to white.
For the ground, though, it’s perpendicular to the camera. There’s no sharp transition between the foreground and background. So, it needs to be a smooth transition. The further the ground gets from the camera, the more blurred it becomes.
The final step is to run the Lens Blur filter, using this layer mask as a depth map. This then causes the background to be blurred, coming into sharper focus as it gets closer to the foreground. Our main subject, the person in the foreground remains sharp throughout.
So, while it is a simple three step process, it is a rather long one, especially the whole masking bit. But this is why people spend so much money on those fast lenses. For a start the results just look better if you can do them in-camera anyway. But, the money spent on the higher end super fast glass is easily saved with the amount of time you don’t have to spend sitting at a computer.
But, if you’re on a low budget with basic kit, have a lot of time on your hands, and want to give it a try, this can be a good option.