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Depth of Field - Some General Things to Think About

Derek McMorrine Derek McMorrine 81 posts

Depth of field is the distance within an image where the subject is sharp when compared to the background. Increasing the depth of field will keep the focal point of the image sharp, while blurring the background further. This technique can give the sense of something coming out/forward from the image and influence ones perspective. Depth of field will vary depending on aperture (F Numbers), focal length, focal point, distance from your subject and potentially camera type, depending on how much control you have over your camera’s settings.

To control how much of your image is in focus you will need to think about focal length, distance from your subject and aperture (primarily).

If you are looking to provide a shallow depth of field (a small focus point with a lot of blur) you need look to set your camera to a large aperture (which confusingly is a low F Number, such as F4) and have your camera closer to your subject, reducing the focal distance.

If, however, you are looking to have a lot of your photo in focus, but still have a strong blur in the background, you will need to be further away from your subject, but still keep a large aperture (again, this is a low F Number).

Finally, if you are looking to have as much of your image in focus, including the background, you will be looking to use a low aperture (a high F Number, such as F11) and be far away from your subject.

One thing to note, however, longer length lenses, i.e. Telephoto Lenses (300mm-500mm), often appear to create the sense of shallow depth of field, even if you have a mid to large aperture (say F7 to F11). This is because they can be used to make subjects appear larger when you are not able to get as close as you would like – the main reason we all buy them for say wildlife photography.

Now to make things a bit more complicated (sorry) – While you are concentrating on your aperture and focal distance, you must not forget about your shutter speed. If you are looking to use a large aperture (low F Number) to create a lot of blur around a single focal point, your lens will be letting in a lot of light, therefore you can use a faster shutter speed. If, however, you are looking to use a low aperture (high F Number) to create a larger, clearer image, you will need to use a longer shutter speed, which is where you may need to use a tripod to keep your camera steady if you do not have good light – and where is this leading to… Always remember keep an eye on your ISO number, especially if you are using an auto function, as high ISO numbers (say 800 or above) will give you a grainy effect, that will take away the clarity of your images, try to keep your ISO below 400. If, however, you do use a low ISO number, this will also require a longer shutter speed, as your camera will again, require more light.

Below are some examples of my work using depth of field:


Focal Length:55mm
F-stop: f/5
Exposure: 1/60 sec
ISO: 320


Focal Length:105mm (Macro)
ISO: 250
Exposure: 1/320 sec
F-Stop: f/4


Focal Length: 300mm (telephoto lens)
Exposure: 1/250sec
F-Stop: f7.1
ISO: 200

If you are looking for more information on depth of field you may also like this which you can find in the Group’s Journal section.

I hope this has provided some helpful information, but the best way is to learn is by doing. Go out and practice and let us see some examples. Feel free to add your own tips and advice.

Derek

Gene Walls Gene Walls 213 posts

Excellent tutorial on DOF! The information is very clearly presented and will be extremely helpful to many RedBubble members, I’m sure. Nice job!

EdsMum EdsMum 14047 posts

What a great idea, us not so clever people still trying to learn can now at least try your suggestions, thank you.. Will you be running another DOF challenge to test us out now.Shirley