Skill Level: Beginner
Here's a quick tutorial demonstrating how to add lens blurring to any cityscape photo, creating a great abstract effect.
I've chosen the beautiful city of Paris to demonstrate this effect.
Once you've opened your photo in Photoshop, click on the adjustment layer button at the bottom of your layers panel and choose Curves.
Click on the black colour picker tool, then click on the area of your photo you would like to be darkest.
Then do the same with the white colour picker to choose the lightest area.
Don't worry if the sky looks too over exposed, we will amend this later.
Next choose Hue/Saturation from the adjustment layer list, and take the saturation down to -35%.
Now we can add the lens blur.
First right click on the background layer and choose Layer From Background.
Give this layer a layer mask by selecting it and clicking on the Layer Mask button.
In the layer mask we want to paint the area of the photo that will be unaffected by the blur.
Choose a large, soft black paintbrush.
With the layer mask thumbnail selected, paint over the area you want to keep in focus.
Now click back on the image thumbnail.
Go to Filter>Blur>Lens Blur...
In the window choose Layer Mask as your source, and adjust the Iris using the settings shown above.
Click OK to apply the effect, then either delete of disable the layer mask.
Now go back to your Curves layer and apply a layer mask.
With the layer mask selected, choose a large, soft mid-grey paintbrush and paint over the sky to lessen the effect of the Curves layer in that area.
Finally use the Crop tool to trim the edges of the image, in this case I wanted to get rid of the gargoyle in the foreground, and reduce the amount of sky in the image.
And here is the final outcome.
