Today, we’re going to be talking about the Power of Depth of Field in your photographs. When we choose to use any particular lens, we insist that that lens be well-made, particularly in terms of sharpness. Indeed the eye is tuned to focusing on that within the frame which is sharp.
For landscape photography, we usually prefer to have focus extending right from the foreground through completely to the background, so the eye is led through the image because everything is sharp. But when we as photographers select a subject and we zoom in and focus on that, does it automatically mean that everything within the frame needs to be in focus? Or should we just choose to highlight that which we want to be the subject? Well, that depends. If we choose an aperture like f/1.8, the picture will be very different to choosing an aperture of say f/16, f/22, or f/32.
In these photographs taken of Jessica, we can see a very, very significant difference between the two. This shot, taken with a 200mm lens at f/22, shows a very sharp background— and a very distracting background— as against this one taken with the same lens at f/2.8. Let’s have a look at these two shots side-by-side. On the left, a very distracting background taken at f/22; and on the right, a very blurred background at f/2.8. The same series of portraits taken with a 35mm lens, also at f/2.8 though, shows the difference between how one lens will interpret depth of field as against another. That second shot again, taken with a 200mm, but at the same aperture.
Depth of Field is a powerful tool for telling the viewer that which you consider to be significant in the image and highlighting the subject, removing subjects from potentially distracting backgrounds. Photographers who use very long lenses with very wide apertures achieve this effect very powerfully, such as this 180mm f/2.8 lens. For this shot, a 300mm f/4 lens was used; and for this photograph, an 85mm f/1.8 lens was used.
In order to highlight the subject and make the viewer look directly into the model’s face, the camera and the lens was focused on the model’s eyes, making everything else out-of-focus and yet still placing her very clearly in a context. In this image, of course the same technique and the same lens was applied, and your eyes are taken directly to the subject’s face. The advantage with this, of course, is also that in available light circumstances a wide aperture can be used and hand-holdable shutter speeds can be employed.
For landscape photography, though, it’s a different kettle of fish. And photographers who shoot landscapes prefer to use wider angle lenses with small apertures, making sure that sharpness exists from the very foreground right through to the background, and thus leading the eye not only through composition but through sharpness throughout the entire image. That is the nature of landscape photography, and of course as such, would call for smaller apertures and greater Depth of Field.
For macro and close-up photography, small apertures are usually used along with flash of course to give a shutter speed that can be used to take a picture. Lenses like a 90mm microlens are very effective for this.