I was going to label this Aperture and Bokeh. But the definition of bokeh is the quality of the out of focus part of your image. I don't want to make this assignment more complicated than necessary so I am addressing just the technical aspect, and leaving the artistic part open to interpretation.
Most of you already know this stuff. I hope to help those that don't totally understand it, and to give those that do some extra things to think about.
So here is a video that explains depth of field pretty well. It's only about 15 minutes and easy.
And here is a pdf with photos illustrating what I think are the main things to consider when deciding on aperture, depth of field and the type of look you are trying to achieve with your photos.
THE ASSIGNMENT: (edited Nov. 8)
I want you to take photos with shallow depth of field. The requirements:
1. blurry background and sharp eyes
2. shoot wide open. (the largest aperture on your lens--smallest number)
3. The photo must include a dog as the subject.
4. Since we are learning about how aperture and lens affects DOF, every photo posted must include the focal length and the aperture setting (85mm f2.8)
Experiment with how to get the background out of focus and have the eyes sharp.
The pdf explains the principles on how to create images with shallow depth of field, but to summarize:
1. Use a large aperture (small number)
2. Use a longer focal length (larger mm for your lens)
3. Get closer to your subject.
4. Get farther away from your background.
I know for some of you it will be a challenge as you will need to set your focus point on single point and be more critical when focusing. Make sure that single focus point is on the eye of your dog. It's harder at wide apertures. Take more photos if necessary. It may require learning about the focusing system of your camera a little better. Practically everyone expressed interest in learning to take great action shots. Well, this lesson and understanding the focusing system of your camera are both critical first steps to getting there.
Thanks for reading if you get this far, and I look forward to seeing you practice these principles.