Since all year levels from Grade 3-Grade 6 last year did my Photography 101, I thought that I would get the older students ready for Photography 102. Now they know a little bit about how Photoshop works, I wanted to teach them the principals of depth of field and how it’s used.
Simply, the depth of field in a photo is the area that is in focus. A shallow depth of field means a small amount in focus, a wide (or deep) depth of field has most of the area in focus. I explain to the students that a camera lens can only focus on one single point. The area that stretches in front and behind that focus is the depth of field.
We look at some portraiture examples of how a shallow depth of field can help bring the subject to sharp focus. We look at examples of macro photography that does the same thing.
Now a camera in automatic mode will likely try to bring the photo into as much focus as possible. When you want to play around with that, on a SLR camera, you could be adjusting the focal length of your lens or adjusting the size of your aperture, which is measured in f-stops. The wider the aperture, the smaller the f-stop value. This greatly depends on the lens of your camera.
Now, remember, we are currently using iPads to take photos, so unless you use a specialised app, you can’t play with the aperture. Even with those apps, it’s essentially faking the effect. I would rather discuss aperture when we eventually get some SLRs in, so what we are doing is faking the effect inside Photoshop.
The workflow is pretty easy to understand. Load up a photo in Photoshop, select the background, and soften the focus. For our purposes, that’s all there is to it. Of course, professionals would go to great pains to make the effect look as natural as possible by perhaps feathering the effect, and so on. But the students are really only looking at blurring out the background.
So we go back to the techniques we learned last year about selecting an area in a photo using the quick selection tool and brushing a selection using the Quick Mask tool. Those two are the best ways, but I also showed them the lasso tool as a way to start of making a selection and then refining it with the tools they know.
Here is a before and after of the image of my daughter that I used for the example.
The students had to go out and quickly take their portrait shots. Each pair partnered up with another and their partner group took a photo of them. The photo of themselves is what they used for the work. I told them that they needed a photo that had some distance behind them otherwise it wouldn’t be as effective.
The lesson was understood very easily, but students are still at varying degrees of getting their selections perfect. But for this project, accuracy wasn’t so important, as we wanted it to look more or less like a realistic area not an absolute exact measured out area. In other words, we were trying to make it look imperfect so you can’t tell it’s photoshopped.
Here is the video where I explain the techniques in creating the effect inside Photoshop:
And here are a few of the students’ examples: