One of the benefits of an SLR camera over a regular point-and-shoot is that an SLR gives photographers more manual control. This means photographers can adjust shutter speed and aperture as well as other controls to get the exact picture they want. Manipulating depth of field allows photographers to attract the viewers attention to a certain place in the photograph.
Depth of field refers to how much of the photo is in focus from foreground to background. A shallow depth of field means that only a small part is in focus. A large depth of field means that most or all of the photo is in focus. Changing the aperture of the lens effects the depth of field in the photograph. A large aperture diameter causes a very shallow or thin depth of field and vice versa.
Photographers shooting portraits often use a relatively large aperture diameter (small f-number) because they want to isolate their subject. Shallow depth of field will put the subject in focus, but blur the background. A blurred background helps take attention away from possibly distracting background objects. This blur is often referred to as bokeh and will look different and often more appealing with better lenses.
I took this picture of Camilla on f4.5 with my 50mm lens so her face is in focus, but the background isn’t too distracting.
Landscape photographers tend to use small aperture diameters (large f-number) so that their subject will all be in focus from foreground to background.
I took this picture of Old Faithful in Yellowstone NP with an 18mm lens at f11
In food photography, photographer have to choose how much depth of field they want in their photos. Often food photographers choose a shallow depth of field and focus on the foreground or a prominant object, while allowing the background to fade into a blur. This helps to make the food stand out from the background and catch the viewers eye.
I love Mexican food, so Camilla made Chorizo con Huevos for me this week. In China we can’t buy very good sausage, but there is plenty of pork. Below is an example of how changing the aperture can dramatically effect the depth of field. (It is also an example of how small our apartment is!). I was debating between the f5.6 and f8 photos, but chose the f5.6 in the end for the final blog post. I like how it shows enough of the subject detail, but not too much background.
Note that there are other factors besides aperture that effect depth of field. These include lens focal length and how close the lens is to the subject. Therefore a lens with a long focal length such as 200mm will need a much higher f-number (smaller aperture diameter) to keep everything in focus than a wide angle lens like 18mm. Also, in macro photography the depth of field will often be very shallow because of how close the lens is to the subject.
Tips for using Depth of Field in Food Photography
- Food doesn’t move, so experiment. Try different apertures and see what looks good.
- If your camera has “live view” check out what the depth of field looks like before you press the shutter release.
- Choose your focus point carefully, especially when shooting with a large aperture diameter. Focus on something interesting!
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