So what really is DoF? Depth of field is the zone within a photograph which is in focus or is sharp.
So why are people obsessed with DoF?
DoF is the very first thing that an amateur photographer can easily achieve to impress anyone. And also DoF is mostly equipment dependant and not everyone has access to these equipment.
DoF is particularly critical for two group of photographers, one group is landscape photographers, the other group is portrait photographers. Landscape photographers want a ‘far’ or large DoF so that most of the foreground to the background is within the ‘sharp’ zone. On the other spectrum is the group of portrait photographers who wants a shallow or small DoF so that the subject is in focus and separated from the blurred background.
So what governs DoF?
A few factors governs how large or shallow the DoF will be:
In general, the larger your aperture, the shallower the DoF and vice versa. For portrait lenses, you can find that they are usually equipped with eye popping F/2 or lesser. The DoF on the F/1.4 lenses is so shallow that the nose and eye lashes of your subject can be in focus but the eyes are already out of focus! While if you want larger DoF, you simply do the reverse and increase the aperture size. However, it does not mean that if you turn it all the way up to F/22 your photo will be the sharpest! All lenses have their “sweet spot”. They usually falls in between F/4 to F/16. For more information on Nikon lenses “sweet spot” please check out here.
2) Focal Length
The longer your focal length the shorter the DoF you have. Sometimes if you do not have a fast F/1.4 lens for portrait, you can use a longer focal length lens like a 300mm to get a similar DoF. However please remember that with a longer lens, your minimum focusing distance will increase. You may need a walkie talkie to communicate with your model if you use a 400mm lens to shoot a full body portrait!
3) Distance of subject to camera
A lot of people (even more experienced photographers) missed out the distance from your subject to the camera also play an important part in determining DoF. The nearer you are to your subject the shallower your Dof will be from your background.
This is another subject which is particularly hotly pursue by most amateur landscape photographers. Hyperfocal distance settings means the a certain “sweet spot” in a particular lens that allows for maximum depth of field. This mystical “sweet spot” can be hard to find or put into practice because we carry at least a few lenses when out shooting. To remember all their hyperfocal settings is almost impossible.
I will update more about Hyperfocal Distance when time permits.
Link: DOF Calculator