iyernat wrote:
Folks - I am not a newbie but rarely find time to learn all the tricks and hence I am an auto-setting user on my Nikon D7100. I only have three lenses - 18-55, 35mm/1.8 and 50mm/1.8.
I want to know how to take a picture of a person who is running but is fully in focus, however everything around him/her is blurred. I have seen pictures of famous athletes like this. I was just curious. Any and all help is appreciated.
For a subject that's running directly toward you, a long focal length lens with a relatively large aperture is the best way to get a strong background blur...
Above was done with a 300mm f/2.8 lens nearly wide open at f/3.2.
The subject is moving more slowly, but here's an even more strongly blurred background (there's a railroad track, buildings and other in the background)...
That was accomplished using a 500mm f/4 lens with a 1.4X teleconverter, for a 700mm f/5.6 combo, with aperture wide open.
Distances between you and the subject and between the subject and the background are another key factor. Below was shot with a 500mm f/8 lens at a fairly close distance (about 8 feet), while the background was about 2X farther away (a fence and firewood pile)...
Higher magnifications are another big factor.... macro lenses render very shallow depth of field and strongly blur down backgrounds. For example, notice how only a few millimeters of the below image fall within the plane of focus...
The image above was shot with a 180mm macro lens near it's maximum life size magnification. I don't recall the aperture but it was probably stopped down a little from it's maximum of f/3.5... maybe f/5.6.
A little or a lot of background blur creates a sense of three-dimensionality in a two-dimensional image and can really help "separate" or isolate the subject from the background... or even foreground... so that the more sharply focused subject stands out better in the finished image.
And, yes, using a slower shutter speed in combination with a panning movement with camera and lens that's tracking a moving subject is another way to cause the stationary background to blur...
Panning techniques such as above generally only work when the subject(s) are moving primarily perpendicular to the direction you're pointing your camera... i.e., when they're moving right to left of left to right across your field of view. (Though there is a "zoom panning technique" that can be used with subjects moving directly toward you.) When doing panning techniques, take lots of extra shots. There are always a lot of spoiled images... fewer "keepers". That's just inevitable when using a slow shutter speed with moving subjects. Practice helps increase the number of good shots you'll get, though. In the above image the panning movement was accentuated by using fill flash (set to second curtain sync... otherwise the subject would appear to be moving backward).
Note: If using a stabilized lens, it may have a special setting especially for panning, so that only the vertical axis is stabilized and the stabilization isn't working against your effort to blur the horizontal movement. Some lenses with stabilization automatically detect panning and go into this mode. Others require it to be set with a switch. Still others simply don't give you the option. If your camera instead has in-body stabilization, I don't know what can be done, if anything. I just don't use any cameras of that type. Maybe someone else can advise.