October 25, 2023

Lens blur without a fast lens

Now, you can create lens blur in your photos without a fast lens, thanks to the new Lens Blur feature in Adobe Lightroom.

Portrait and wedding photographers love that blurry effect behind a subject, sometimes called bokeh. Very often, those photographers are spending hundreds of pounds on fast lenses. The widest aperture on these lenses can be as wide as f/1.0 to f/2.8. These lenses can be very expensive, so often, beginner photographers can be disappointed when they try to get similar results from kit lenses. However, the latest update to Adobe Lightroom, Lens Blur, might get you closer to achieving the results you’re looking for.

I can’t see Lens Blur in my version of Lightroom

The new Lens Blur functionality is available in Lightroom 13.0.1, released on 10 October. As this update is a new full version number, you must also update the Lightroom catalogue. The first time you open Lightroom after the update, you will be asked to upgrade the catalog. Once you’ve done this, you won’t be able to use the older versions of the catalogs. It’s an excellent opportunity to free up some disk space by entirely deleting any backups you may have taken of the version 12 catalogs.

Where do I find Lens Blur?

The new Lens Blur functionality is included in the Develop module. On the right-hand panels, scroll down to find the new box included. You’ll see Adobe is doing something quite strange with how it releases new functionality. It has a Beta program that is easy for anyone to subscribe to, and it was here we saw the AI functionality rolled out. However, while the Lens Blur functionality is included in the full-release version of Lightroom, it’s being badged as ‘Early Access’ functionality.

How does it work?

Let’s use the image below to see the new tool’s capability (and limitations). I’ve chosen this shot from a few years ago. It was shot at f/7.1 at 16mm focal distance, so while there is a clear focus on the three subjects, there’s still quite a bit of detail in the foliage behind.

Pressing the Apply checkbox will automatically apply 50% blur using the standard circular bokeh that most modern lenses would create. You can adjust the amount of blur being applied by sliding the Blur Amount between values of 0 to 100. Zero value is the same as if you hadn’t pressed the apply button. You can see the effect below at 25%, 50%, 75% and 100%.

With the default Lens Blur setting, the subject is selected using AI. You might be able to see that, with this complicated set of subjects, the AI isn’t quite doing the job required. I’ll show below with a crop on the 25% full-sized image where some of the limitations are.

Zoomed in, there are a couple of clear issues in how the AI has selected the subjects. The selections are much sharper than you would see in using a shallower depth of field in-camera, so the people in the shot look like they have been cut out. The bell of the trombone is level with the head of the sousaphone player; however, as the AI isn’t using a depth-mapped image, it has struggled to select the image correctly. As a result, the trombone has had more bokeh applied to it than would have occurred naturally. There is a similar issue with the bunting tied around the bell.

Bokeh types

When you have selected and applied the appropriate amount of blur, you can change the type of bokeh that is applied. The five options, displayed below from left to right, are;

Circle – Modern circular lens.

Bubble – Standard circular shape with over-correcter spherical aberration.

5-blade – Penta effect, commonly seen in vintage lenses.

Ring – Commonly seen in reflex or mirror lenses, also known as “Doughnut”.

Cat Eye – Typically caused by optical vignetting in certain lenses.

You can increase or decrease the intensity of the blur effect by adjusting the Boost slider.

Refining the selections

So far, we have been adding and adjusting default settings. However, further down the Lens Blur section, we have some tools that help refine where the effect will work. First, Let’s adjust that trombone issue by extending the focal range. The AI functionality has created a depth mask to identify how far elements of the image are away from the camera. The focus range bar represents things close to the camera on the left side and further away on the right. By dragging the box, which represents the subject selection, left or right, we can adjust the areas which remain in or out of focus. Stretching the focal range much further to the right has brought the bell of the trombone back into focus, but it has also affected the other parts of the image that have been selected with the same depth.

Final refinements

There are still some issues that the Focus Adjustment slider hasn’t entirely fixed. The trombonist was wearing a headdress with skeletons on it – it’s still not selected as the subject. The three subjects still feel like they have been cut out of the scene. This is where we can use two adjustment brushes in the Lens Blur Panel.

Click on the Focus button will add focus to areas that are painted over. Lightroom can automatically detect lines if you check the Auto Mask button. This has allowed me to select the headdress accurately. The cut-out effect can be adjusted by selecting the Blur button, and you can now paint in blur to the image. Selecting a small brush and deselecting auto-mask has allowed me to paint over the edges of each subject to apply a small amount of blur to allow them to blend into the background.

It’s just a start

Remember, this is an Early Release development to Lightroom. You could almost call it a Beta release in production. Undoubtedly, the selections will improve as Adobe develops the tool even more. Honestly, the post-processing version of bokeh isn’t yet as good as using a fast lens, and it will never be as satisfying as taking a good shot in camera. However, if you’re prepared to spend a bit of time getting to grips with the tool, it has the potential to make up for any deficiencies you might have in your kit bag.

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About the author

As well as running Edinburgh Photography Workshop, Rich Dyson is a professional photographer. His photographs are regularly used in newspapers such as The Times, Guardian and Daily Telegraph. He also had two solo exhibitions and was featured in a members-sponsored exhibition in the Scottish Parliament. You can see and buy his photography at richdysonphotography.com.

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