The Lens Blur filter gives the effect of a narrow depth of field, keeping some parts of the image in focus, whilst blurring the rest. This filter allows you to take photos which as perfectly crisp and clear, and add selective blurring later, with wonderful control over Highlight (keeping the whites bright), Iris and Noise, together with of course the degree of blur.
Often it’s a distracting background that can spoil a photograph for us, or maybe you’d just like the photo to have a dreamy feel without additional filters. Obviously, you don’t want the whole photo to be blurred, so you need to tell Photoshop just where you want the blur, and how much. We do this with simple selections with the selection tools, or with masks & alpha channels - basically it treats black as though it were in front of the photo, white will be more at a distance, with shades of grey in between.

In my example I’m using a photo of baby Joshua, I love this photo but fell it could do with a bit of dreaminess. Maybe for practice you could find on to which you’d like to give the same type of look?

Step 1.
Open the photograph you want to work on & duplicate it as you don’t want to work on the original. Then use one of the selection tools, probably one of the lassos to make a selection around the subject, in my case baby Josh. Don’t worry about being too accurate, because now you are going to soften the edge with feathering. I have given mine a feather of 60. Now Select > Inverse so that the background becomes blurred not Josh! (If you forget this step Photoshop have provided for you! There is a check box in the filter itself for inverse!)

Step 2.
Once you have saved your selection, click on the “Channels” tab, just to the right of the “Layer” or at the top, Window > Channels. Scroll down & you will see your selection at the bottom waiting for you. At this stage your selection is saved, you can deselect, make further selections in new channels.
The screenshot to the left shows the “eyes” clicked on in each of the channels – try clicking the RGB one off & see what happens? Yes, you see your subject in black on a white background – just what you want as remember, the lens blur will see black pixels in front, white further away. To add to the softness, I pulled a radial gradient, black to white, from the tip of Josh’s nose (the point that would be closest to the camera) out to a corner..

Step 3
Now click off the eye on your selection channel in the channels palette, and return to the layers palette. You will notice that the top layer ( mine is labeled” Background copy”) is grey, click on this to activate it. Select Filter > Blur > Lens Blur.

Step 4.
You will now see the Lens Blur’s dialog box (see left) with a full preview of your photo.
1. Click here to zoom in / zoom out.
2. Preview is checked by defauklt so that you can see what is happening. Just below are 2 buttons faster & More Accurate – leave Faster checked for now, More accurate slows things down considerably & does NOT affect the final result, only the preview.
3. In the drop down box – if you are following my example select as the source your selection channel, in my case its Baby Josh.
4. Blur Focal Distance affects the degree of blurring, move until you are happy with what you see. If as I have in my example, a depth map loaded you can click in the image to fine tune the blurring – I found that clicking on his right eye gave me the best result in the end.
5. Specular Highlights – one of the features which makes the lens blur so good – in normal blurring, white pixels take on a grey tinge, this slider allows you to whiten the whites!
6. It seems you can safely go higher on the brightness, but very carefully with Threshold – a tiny movement makes a huge difference.
7. Noise & film grain are softened by blurring, add them back with this slider – I chose 3
The Iris sliders I left default. At this stage I don’t know enough about photography to be able to be too critical of them – but if you do, they are apparently wonderful!

The final result – my dreamy picture of Josh in the Sun!

I do hope you have enjoyed working through this tutorial – there is LOTS more in the lens blur, read up on it & play with it all you can! As with anything in Photoshop there are many ways to do everything – this is just one of the many ways you can use the lens blur – I hope you will find lots more

Meryl

Tutorial: ADDING DEPTH OF FIELD USING THE LENS BLUR OF PHOTOSHOP CS By Meryl Bartho

Tutorial: ADDING DEPTH OF FIELD USING THE LENS BLUR OF PHOTOSHOP CS
By Meryl Bartho