Depth of Field

A basic definition of Depth of Field (DoF) is: the area of acceptable sharpness within a photo that will appear in focus. In every photo there is a certain area of your image in front of, and behind your subject that will appear in focus.

It is the distance between the nearest and farthest objects in a scene that appears acceptably sharp in an image. If everything is in focus then you have a large DoF. If very little is in focus then you have a shallow or small DoF. 

It might be easier to remember this simple concept: The lower your f-number, the smaller your depth of field. Likewise, the higher your f-number, the larger your depth of field. For example, using a setting of f/2.8 will produce a very small or shallow DoF while f/22 will produce a big or deep DoF.

The Aperture you use is a big factor in determining how much DoF you get. A small F-stop will produce a small depth of field. A large F-stop will produce a large depth of field. Another factor you need to keep in mind is the length of your lens and how close you are to your subject. All three of these factors determine how much DoF you end up with in your photo. The closer your subject is to the camera, the shallower your depth of field becomes. Therefore, moving further away from your subject will deepen your depth of field. 

DoF is not always evenly spaced throughout your image either, it’s usually about one third in front and two thirds behind your focal point, but as your focal length increases it becomes more equal.

DoF is often the most difficult of the three variables to learn, and people often get confused. Try shooting the same simple set up like a flower in a vase and change F/Stop to see the difference you get at each, from the same distance from your subject. Don’t forget to adjust your ISO and Shutter Speed.

The Aperture you use is a big factor in determining how much DoF you get. A small F-stop will produce a small depth of field. A large F-stop will produce a large depth of field. Another factor you need to keep in mind is the length of your lens and how close you are to your subject. All 3 of these factors determine how much DoF you end up with in your photo. The closer your subject is to the camera, the shallower your depth of field becomes. Therefore, moving further away from your subject will deepen your depth of field. 

In the photo below I am shooting at about an F/2.8, and you’ll notice that the main garlic head is in focus and then drops into a blur the further back you go into the scene. This would be considered a shallow depth of field compared to if I had the entire photo in focus because I chose to shoot at an f16.

With Macro the depth of field is much tighter since we are much closer to our subject. In the photo below you can see that even though I’m shooting at a medium aperture of 5.6 – much of the flower is still in blur unlike the photo above where there are whole photo in blur.

If we move up to an F/9.0 we are increasing our focus and have a deeper depth of field, but because we are shooting so close to our subject, we are still going to have quite a bit of blur going on in our photo.

When shooting macro you need to be more conscious and intentional in the decisions you make. Don’t just use the same settings you would use on larger objects, because they are the ones you always use. Really take the time to think through your photo and decide:

• How much do you really want in focus?
• Look at your subject and decide where you want to focus and exactly the areas you want in focus on
• How much do you want in blur?
• And how much structure do you want that blur to have?
• How narrow/wide do you want that plane of focus?

Take several photos of your scene using different apertures and different lenses if you have more than one choice you can be shooting with. By doing some of this base work, you will be able to look at the differences it makes with the selections you choose. By doing this for most macro setups you can often be surprised at what you like, after editing them. Always shooting with a small F/stop is not always the best approach, in fact when you are starting off, very frustrating. It is also often a cause of why people give up. Start with a mid-range Aperture, say F/9, on average I usually shoot with a F/4.5, but will also shoot at F/1.8 or even F/11.

Depth of Field