When you see a beautiful landscape photograph hanging on a wall in a gallery, it was very likely was shot on a very small aperture (large f/stop number) to get as much depth of field as possible.

depth of fieldDepth of field is the distance between the nearest and the farthest objects in an image judged to be in acceptable focus. The focal length and the aperture of the lens you’re using and your focused distance govern your depth of field. The longer the focal length, the less the depth of field.

The shorter the focal length, the more depth of field. The smaller the aperture, the greater the depth of field, other things being equal. In layman’s terms, telephoto lenses have less depth of field than wide-angle lenses, and a more powerful telephoto lens gives less depth of field. It also follows that extremely wide-angle lenses provide the most depth of field.

When you see a beautiful landscape photograph hanging on a wall in a gallery, it was very likely was shot on a very small aperture (large f/stop number) to get as much depth of field as possible. Even on a sunny day, using the smallest aperture may require a rather long shutter speed and may therefore require the use of a tripod. This can create a dilemma.

For instance, you would ideally want to use a high shutter speed for shooting action photographs. Yet the subject is traveling at speed, so a small aperture would give you more of the subject in focus, thus making it easier to get the picture sharp. Some people would just use a higher sensitivity for their sensor, thus enabling higher shutter speeds and lower apertures. But this comes at a price—and perhaps the most expensive price when it comes to photography— the all-important quality of the image. The sad fact is that as you increase the sensitivity of your sensor, the image quality can decrease. (Camera manufacturers are improving greatly in their high-ISO performance as we write this.)

So now it’s decision time: You can’t have everything, so you have to choose what is most important to you. Even on the brightest day of the year, with the sun on the subject, if using 100 ISO, your exposure at 1/1000 second would be f/5.6. This would not give you much depth of field on a long telephoto lens. And if you were photographing floodlit football, you would really be in trouble. A typical exposure setting would be 1/500 second at f/2.8 at 800 ISO.

When you would like as much depth of field as possible, remember that the depth of field extends farther behind the point of focus than in front of it. If you focus one third into your subject, you will know that the depth of field will extend by equal amounts before and after the point of focus. Some lenses have depth-of-field markings showing approximately how much depth of field is available at a given aperture. To give a crude example: with a 20mm lens set to f/11 and the focus set approximately 5 feet into the picture, your depth of field will extend from 2 1/2 feet to infinity. Using a 400mm lens set at f/4, your depth of field with the focus set at approximately 30 feet would be less than a foot.

Remember that you can use depth of field creatively by using a wide-open aperture to isolate your subject. Your subject will stand out sharply as the rest of the image surrounding it remains pleasantly blurred. Equally, with a wide-angle lens and a small aperture, almost everything in your picture can be sharp, enabling you to fill the frame and isolate your subject in the foreground while keeping a sense of place with a sharp background. To sum up, the smaller the f-stop, the more depth of field you will get. But always remember to use a shutter speed that is suitable for your subject.

You may need the articles below :

Tagged with: • • • • • • •

Filed under: Concept

Like this post? Subscribe to my RSS feed and get loads more!