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Depth of field

Sunday, 09 December 2007

Depth of field is often mentioned when it comes to photography and paintings. What exactly is that and how can we achieve this in a painting? This is what I am going to talk about with this issue. Depth of field is used to have a painting not appear flat. Photo lenses use the fact that our eye focuses on a point which will then appear to be sharp. Everything closer or further apart then the focus point will look more blurry. Take a look at those pictures as example. In general it will help you understand how to paint and why to paint a certain way if you make it a habit of studying pictures or nature. It will in term help you guide the eye of the viewer to the point in the painting you think is the most important. The most obvious use of depth of field is of course within a landscapes. The further away objects are from the main focus the more desaturated and blurry they get. Now, on order for your painting to not look flat we also have to take a look at the smaller details. Depth of field pretty much applies to every object you are painting not only to the painting as a whole. I will be showing you a rough process of painting an eye and how depth of field in small makes a big difference. Brush it If a painting appears to look flat, the painter most often used the same brush strokes all over. Meaning your eye doesn't have a guide or something to rest on. In order to create the depth we need we will use different brushes to help us in the process. As a very rough rule of thumb the farther away from your focus point something lies the softer it's edges. Now to start off I grab my most used brush and block in the general colors and shapes. All pretty flat and rough for now, right? This is what it looks like after a few minutes of work. The brush settings for this brush are as follows: Brush Tip Shape -> Spacing: 10% Other Dynamics -> Opacity and Flow: Pen Pressure Smoothing checked With the colors roughly in place I use the airbrush tool to smooth out some of the transients. It is important that you don't overuse the airbrush. Nowadays I use it extremely rarely..maybe 1% of the whole painting process if not less. One other thing you need to keep in mind is the fact that you need to know which transients need to be smoothed out and which not. The cheek for example is of course a roundish shape and has soft edges. But where it meets the nostrils or say the eyelid it will have of course sharper edges due to the form of said objects. You can see that I started to blend some colors into each other in this step (namely the cheek and a bit over her eye). It still feels quite flat but due to the fact that we used a slightly harder edged brush on the first step and now the airbrush tool we start to work out a more natural and less flat look. If you are having troubles with blending the colors nicely you can always set the flow as low as 4% manually while painting. The brush settings for the airbrush: Brush Tip Shape -> Spacing: 25% Other Dynamics -> Flow: Pen Pressure Smoothing and Airbrush checked Now that we used the airbrush we might have lost some of the edges we need to make it feel realistic. Therefor I use a similar brush then the first one we used but with slightly different settings to work on some harder lines again. Keep comparing the earlier steps and try to see the differences the brush strokes make. Specially the inside of the eye and the edges of the eye lids need a bit more sharpening now. That will lead to the impression that the actual eyeball is slightly further back. The difference is hardly noticeable but it will enhance the overall feeling immensely. The brush settings for this brush are as follows: Brush Tip Shape -> Spacing: 10% Shape Dynamics -> Size Jitter: Pen Pressure Other Dynamics -> Opacity and Flow: Pen Pressure Smoothing checked Speaking of brushes I should mention how much a speckled brush can add to the realism of painting skin. Little imperfection can add that little difference to not have skin appear flat. Using a brush in places where the values between two different colors vary strongly will fetch you the best results in giving the impressions of skin pores. Take a glance at yourself in the mirror and you will see that there are places where the skin naturally consists of bigger pores (the skin beneath your eyebrow for example). Now comes one of my favorite steps while painting and I have to admit I fight with myself almost every time to not use this too early during the process. As we go from a very soft brush to harder ones we now are at the step where I am using the hardest brush I have. This is also the one I use for sketching at 50% flow. I have to stress that you should use this brush at very few places. If you overuse it it will in term flatten the image down again. We do add the strongest highlights and the sharpest edges now. The sharper a highlight is the more smooth the surface beneath it appears. Since the eye is a wet sphere it will of course have the harshest highlights. The same applies to the inner corner of an eye. Once more feel free to compare with pictures to see how nature applies). Even though we haven't painted an actual sphere for the eye it appears that the highlights are closer to use and cheat our eye in thinking that there is an actual form beneath. The brush settings for this brush are as follows: Brush Tip Shape -> Spacing: 25% Shape Dynamics -> Size Jitter: Pen Pressure Smoothing checked Now that we have a nice base in place I start to add more little details like the eyelashes. Once more a tiny detail which uses depth of field to create a more realistic approach. Using the airbrush tool we used earlier, you can paint in single lashes. Remember here that they are not nicely separated. They naturally cling together sometimes and have various weight themselves. Now the trick is to use the eraser with the settings of the first brush we used. You can then workout and harden the very tips of the lashes. That basically means they go from blurry to hard which in terms make them appear to start further back and come more unto focus. (Our depth of field explanation again). To finish this you might want to take a step back and look at what we have now. Try to figure out which parts lay further back or closer to the viewer and compare their blurriness or sharpness. Does it make sense? Do you need to sharpen some line or smooth some others out to enhance it further? Concerning painting the actual eye: I added some color variations to the iris and also used another brush (much like using a toothbrush on paper) to give the skin some more texture. I could work on this some more as it is far by perfect but I think it worked nicely to explain some of my points. Depth of field and the blur tool. Another fast and easy way to create more depth in your painting is to use the blur tool. I am not talking about the actual blur filter because I think it doesn't give you enough control. It's is easier and more accurate to use the actual blur tool. I am using a book cover I am currently working on to show you how I created a bit of depth in this forest scene. Obviously the main character and everything that is on the same level as her are the most crisps (1). Then there is a second level which is supposed to be just slightly further back (the leaves hanging in from the top right (2)). To further enhance the sharpness of the actual main level I added a third one behind the rock in front (3). And last but not least the actual background level (4) which is pretty much out of focus. Something you can't see on this cutout: There is another level in front of the character consisting of some big leafs hanging in from the side which are also out of focus. All those levels of blurriness help you not only in having the viewer look at the most important parts first but it also gives a nice depth to the painting as a whole. Basically, I use the blur tool to create those levels. The actual background starts of with pretty much everything containing the same crispness. You will notice that using the blur tool at parts will “push that part back”. It is actually quite fascinating to see that happen. Try it out!

 

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