Digital Diversity

The term ‘Bokeh’ comes from the Japanese word for blur (or so i have read). This term is used for the photographic technique of blurring the background while keeping the subject in focus.

Different people have different ideas about what they would class as a decent bokeh. Some insist it adds something to the picture, some only class a decent bokeh to be one that creates nice circles of light within the blur. Seeing as this is a tutorial aimed more towards the beginner level I will simply be working on the basis of standard blurring of the background in Photoshop. Its main purpose being to help the subject stand out without background distractions.

It is created by something called the Depth of Field (DoF). This is the area in which your photo will be in focus and where it will start to fade out of focus (start to blur). There are 2 main factors involved in controlling the Depth of Field. The aperture and the focal length.

Aperture

Quite simply, the larger the aperture (smaller number) the more blur. This is because larger apertures have smaller Depths of Field than small apertures.

Focal length

You may have heard people tell you to use full zoom when trying to achieve a blurred background. The focal length doesn’t make your depth of field larger or smaller, what it does do is change how the DoF is distributed. For example, using wide angle focal lengths at an aperture of 2.8 will have the same DoF as using full zoom at an aperture of 2.8. However at the wide angle you will have less in focus in front of the subject (point of focus) and more behind. With the telephoto you will have more in focus in front of the subject and less behind. This makes it easier to blur what is behind the subject.

Another aspect that effects this is your distance to the subject. The closer you are the smaller the DoF and therefore easier to blur the background.

If that all sounds a bit confusing try reading this website http://www.cambridgeincolour.com/tutorials/depth-of-field.htm
I found it explained it fairly well with some nice diagrams to help.

Sensor size

Your cameras sensor size also comes into play with this type of photography. You may often hear people tell you that you cant achieve these bokeh shots with a compact because of their tiny sensors. Well clearly this isn’t completely true. I use a superzoom with a tiny sensor and the example shot at the top clearly has bokeh. The reality is that the smaller your sensor the harder, it is to achieve. This is because smaller sensors naturally have larger depth of fields due to how the smaller sensors and lenses work.

The opposite of this is also true. The larger your sensor the harder it is to have a large DoF. This means your compact actually has a small advantage over larger sensor cameras (such as DSLR’s) for landscape photography where you want everything in focus.

To get round this issue you need to be closer to your subject and you need to use maximum zoom. Also make sure the background is as far away as possible from your subject. What you wont be able to do is have such a shallow depth of field that you can blur a background that’s right behind your subject. Saying that, even DSLR’s need a specific lens to achieve this but you need to know your limits.

What ever camera type you have the basic rules of aperture and focal length apply. The best way to blur your background is to use full zoom and as large an aperture as possible.

In this shot i used full zoom, was about 1-2 meters away and had the aperture wide open. As you can see the ape is sharp while the background is nice and blurred.

Faking it

Sometimes you may find it hard to get the DoF right or you just didn’t think about it at the time. You then put the image on your computer and think it would have looked better if you managed to blur the background. Well you can fake it in Photoshop (CS or elements). It is however tricky to do so be warned, to get a good result can take time. It is always better to try and achieve this in the original shot, especially with hairy subjects. Trying to mask around hair isn’t the easiest thing to do and your final result can look a little odd if not done right.

I will use another of my Gibraltan Ape images that had no bokeh to show how this is done. If you try this yourself you will see how hard it can be to get hair masked properly. With time and patience it can be done. This is a lot easier to do on subjects with smooth, easy to follow outlines.

Right, lets get the starting image up.

This image really could use a blurred background. The people standing there take something away from the subject and make the shot a little crowded.

First thing i did was crop the image slightly. This is to frame the ape a bit better.

Now duplicate the layer. Right click the layer your image is on and click duplicate.

With the new duplicate layer selected you need to add a Gaussian blur.  Filter > Blur > Gaussian Blur.

In the Gaussian blur options window, move the slider till the blur amount you want is achieved. For this one i used 25.

You will notice the whole image is now blurred. Before we do any masking you need to make a duplicate of the blurred layer. Right click it and select duplicate from the menu. Make it invisible by clicking the eye on the left of its layer window. Finally add a mask to the top blurred layer.

If you are unsure of how you use masks please visit the layers and there masks tutorial.

Your layers window should now look like this if using CS.

If using elements you will have an extra layer in there for your mask.

The reason we use 2 blurred layers is to create a fading effect that simulates how depth of field works. The top blur layer will be for the main background while the second is for the closer parts of background that lead up to the subject. The idea is to created a gradual blur near the subject that looks more realistic.

So for the top blurred layer we are going to blur the distant background and the area with the people standing behind the ape. Carefully unmask the ape and the area near him. Use a soft brush and be extra careful around the fur. If you end up with hard edges that don’t look right, try using a larger softer brush to slightly blur the tips. This should help it blend a little better.

Now select your other blur layer (the one below). Click the eye to make it visible again. You will notice the whole image blur. Add a layer mask to this layer and select it.

Now select the gradient tool (a rectangle that fades from black to white). Make sure you are using a white to black gradient. Then create a gradient from the top of the apes head going to its feet.

If you havn’t used the gradient tool before then this is what you do. You click and drag it. By this i mean to click where you want the gradient to start, then drag (without releasing the mouse button) to where you want it to end. You should notice a line going from where you clicked to where you are now. Release the button and the gradient is created.

You should now have a gradual blur going from the apes head to its feet.

With the mask still selected, use white to reveal all of the ape and the area on the floor in front of it.

When done you may find that this layer isn’t blurred enough. To fix this simply duplicate the layer by right clicking it and selecting duplicate.

You should notice the blur is now a bit stronger. If you find it to strong then simply reduce that layers opacity a bit.

If you look at the image you will see there is a brown haze going around the apes head. This is an effect of using the blur tool. What we want to do is tuck that in behind the mask so it is no longer visible.

To do this you need to select the smudge tool. It looks like a finger.

This tool literally smudges the work by pushing the pixels about. So with this tool selected, selected the top blur layer and smudge the brown haze into the masked area. So click on the brown haze and without releasing the button drag towards the apes head. You should notice the haze disappear. When done i cropped the image again to frame it a little better.

Due to the trickiness of this technique you will have mixed results. The fur makes this one more challenging than most. The result here is OK but would look a lot better had i got the shot right in the first place.

Here is another example of a bokeh i faked for someone and i think it had a much better result. The technique i used was exactly the same.

There you have it. Bokeh – how its achieved and how to fake it.

Tags: aperture, blur, bokeh, elements, flowers, layers, lighting, masks, panasonic fz28, panasonic lumix fz28, photo editing, photography, photoshop, telephoto, thoughts, tutorial, tutorials

This entry was posted on Monday, August 24th, 2009 at 11:16 and is filed under photography, photoshop. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.