One of the most attractive effects in photography is blurring the background while keeping the subject sharp – this is often called differential focus.
It’s a widely used technique in portrait photography as it helps to focus attention on the main subject, and also literally ‘blurs out’ background distractions, like cars or bins. NB: you may have also heard the term ‘bokeh,’ which is increasingly used as shorthand for background blur, but it’s actually more about the ‘quality’ of said blur.
Anyway, the easiest and quickest way to blur out the background is to use a ‘fast’ prime lens with a wide aperture of, say, f/1.8, or zoom in close on the subject with a telephoto lens, again opening up the aperture. Make sure the autofocus point is carefully set on the person or animal’s face if it’s a portrait (turning on Eye Detection AF if your camera supports it can help here.)
You may not have suitable lenses however, or the conditions might not be right… or you may take a quick grab shot without remembering to open up the aperture. It is still possible to get nice background blur, however, as more and more editing programs now enable you to recreate the effect after the shot.
Adobe has recently introduced a new ‘Neural Filter’ as part of its latest series of upgrades to Photoshop. Don’t worry too much about what Neural Filters mean, the tool we are focussing on here is called the Depth Blur filter. Here’s how it works.
Open and adjust the original raw file
Assuming you shoot in raw, which we recommend as you get the maximum resolution from your camera sensor, begin by opening the original file in Adobe Camera Raw. Here we have increased the contrast and cooled down the white balance, so make these important adjustments first.
Find the Neural Filters
Then click ‘Open’ to open the image in Photoshop. The relevant tools are found under Filter/Neural Filters. You will need to click to download Depth Blur feature unless you have used it before.
Move the sliders
Once the neural filters are open you can make a variety of further adjustments, e.g. warmth or saturation. To blur the background on your image, move the Blur Strength slider as required; you may need to experiment with the sliders for the best results, but the default settings work pretty well. This is rarely an instant process, however, Be aware that the editing is taking place in the cloud, i.e. on Adobe’s servers, so it can be slow. One tip is to turn off the graphics processor (GPU) acceleration via Photoshop Preferences.
You can also adjust the focal range and focal distance for more realistic looking results and if you are shooting a portrait, you can apply skin smoothing (the AI recognises a human face). It all works Ok but as mentioned, it’s not for the impatient, particularly if you have a slower home broadband connection. This Depth Blur tool is only at the Beta stage however, so it should get faster and slicker when the final release is ready.
Don’t forget your phone
While Adobe’s Neural Filter tools are useful, you may not need to fire up Photoshop just to blur out backgrounds on portraits. Many smartphones now have a Portrait Mode, with sliders to adjust the background blur – it’s a lot faster than the Adobe solution as the phone is doing the processing, rather than it all being done via the cloud. Here is an example from an Oppo Find X3 Pro phone and it can be very useful if you want to really narrow the depth of field, something that can be tricky with most smartphones.
It’s best not to push the background blur slider too far, however, as the results can look a bit artificial and synthetic. At the end of the day, while instant background blur tools are useful, you will still get the most authentic-looking results by getting it right in camera.
‘Fast’ 50mm or 85mm prime lenses, with a wide maximum aperture, are ideal for this – one of the best buys we have seen recently is the Sigma 56mm f1.4 AF DC DN, which you can pick up for under £340. With a maximum aperture of f/1.4 and smooth, fast focussing, you are pretty much guaranteed beautiful bokeh!
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