Part 8 Lesson 2: Depth of field

In this lesson you will review how to use aperture to control the depth of field in your macro image, and learn how to use a shallow depth of field to create selective focus.

This lesson corresponds to Chapter 19 in Book 2.

If you've been with the course since the beginning, there is nothing new covered in this lesson. But everything you have learnt about aperture becomes critical when you are shooting close up.

You will remember that a large aperture (small number) gives a shallow depth of field, and a small aperture (large number) gives a larger depth of field. With macro photography, for any given aperture, the depth of field is much smaller than when shooting at normal distances.

You can use a shallow depth of field to create beautiful selective focus in macro photography, but first you need to know your lens inside out - what will the depth of field look like at different apertures, and at different focussing distances:

Both of these images of the hydrangea were shot with a 100mm macro lens at f2.8. The first was shot at a distance of about 1.5m. The second at a distance of about 30cm.

THIS WEEK'S PROJECT

Methodically get to know one of your lenses, inside out. You can do this exercise on macro mode (but you may have less options to change the aperture), with extension tubes and with a macro lens.

If you are using the reverse lens method you can only use the fixed focus point available (you'll know what I'm talking about if you've tried it). You can change your aperture if you don't mind risking dust on your sensor (ie. you know how to safely get rid of it).

For everyone else:

1. Set up a static subject, the same as last week, in bright indirect daylight.

2. Set up your camera on a tripod, or tripod substitute, at its closest focussing distance to your subject.

3. Pick a focus point, and don't change it (use manual focus).

4. Take a series of images, running through all of your apertures. Don't worry about half and third stops unless you want to. Let the ISO creep up if you need to, at smaller apertures.

5. Move your camera a little further away (10cm or so), and repeat the whole exercise.

6. If you're up for it, move further away and do it again.

Review your images. At what distance and at what aperture did you create a depth of field you like? It's not always the widest apertures that create the most appealing selective focus in macro photography - sometimes having too much out of focus creates muddy, distracting areas in the frame.

Don’t forget there’s an A Year With My Camera app where you can meet other people doing the course. Search on your Apple or Android app store, or click here for more details.