I know that this effect occurs when there's a shallow depth of field.
My question is, what are the various ways I can increase this effect in my photos when I'm taking them?
Note that I'm not asking how to use an editing program to achieve this effect after in post production or after the image is captured.
Here's the list of things that influence depth of field the most (in this particular order):
While using shallow depth of field is the most common technique to get blurred background, there are some other ways:
using motion blur
with a moving subject, use longer exposure and pan with the subject
or switch roles - move the camera, keeping it aimed at a steady subject
Ultimately, you want a shallow depth of field, which means a low fstop number (f/2.8 for example). The lower the fstop number, the more light that gets in, so in order to expose correctly, you need to increase your shutter speed (1/1000 is better than 1/25), lower your iso (100 is better than 400), and if all this is not enough, add a neutral density filter to reduce ambient light, so that you can further open up your aperture.
It's more complicated than just depth of field. You can have two photos with identical depth of field, but one can have more background blur than the other. In addition to background blur, there is also "bokeh", which describes what kind of blur there is. Check out this article which describes it in detail, and gives you a tool for calculating the various parameters.
Obviously, smaller f-stop means shorter depth-of-field, so I'm not going there.
There are a couple of things you can do: 1) Remove the subject from the background as much as possible. How much will depend on the lens and aperture you can use. 2) Use a longer lens. Longer lenses have more narrow DoF.
Hope that helps.
Use a large aperture (small F number) when you take a photo. The larger the aperture the narrower the depth of field will be (compensate with with a shorter shutter speed). In addition you can try to vary the distance between the camera and the subject. The shorter the distance, the smaller the DOF will be.
First of all, start by ignoring all the answers here that talk about depth of field. You are after background blur which, although somewhat related, is really not the same thing as depth of field. Be aware that most people mix this two notions.
The two main factors affecting background blur are:
The tighter you frame (the bigger the subject in the viewfinder), the more background blur you have. If you frame twice as tight you get double the original background blur.
You get this by dividing the focal length by the F-number. For example, a 85 mm f/1.4 (when used at 1.4) has a 61 mm entrance pupil (which is plenty). The larger the entrance pupil, the more background blur. Double the diameter and you get, again, twice the original background blur.
The distance to the background does not really matter as soon as it is significantly larger than the distance to the subject. If this condition is not met, then start worrying about depth of field. Other factors such as focal length, subject distance, crop factor, etc... have no effect as long as you compare pictures taken with the same framing and same entrance pupil diameter.
To increase the effect of "bokeh blur" with thin depth of field, there are a number of things you can do in-camera.
Obviously, opening up your aperture wider will decrease depth of field, but moving from the typical fast prime widths of f/1.4-f/2 into the rarer f/0.95-f/1.2 will have a notable effect, if you can afford the glass, simply because not many people shoot with glass that fast. Be prepared for a big heavy lens, softness, vignetting, and catseye bokeh, though.
Get closer to your subject. The shorter the focus distance, the thinner the DoF becomes. This is why P&S cameras can still achieve background blur when shooting macros.
Increase the distance between your subject and the background. This increases the amount the background blurs.
Use a longer focal length. Longer lenses actually do produce a thinner depth of field, although the effect may not be particularly pronounced, especially compared to shooting from closer distances.
Use a bigger format. Shooting with a larger format of sensor/film has the effect of either causing you to shoot at closer distances or to use a longer lens to compose similar to how you would with a smaller format. Both of these can create thinner depth of field. This is one of the reasons medium format is so prized for portrait work.
Use the Scheimpflug principle with a tilt-shift lens. Changing the shape of your DoF, so that it's no longer perpendicular to your lens by tilting the lens (or image plane) up can also create a fake thin DoF effect. Tilt-shift lens and view camera users often use this to create a "toy/model" effect and shoot landscape shots from above and make them look as if they were small models.
Shoot with a fast lens, a flash, and high-speed sync or ND filters This can still let you get a thin depth of field while shooting outdoors in daylight, but can "pop" your subject even more from the background by allowing for two different lighting levels: one for your subject and one for the background (see this Jason Lee photo on Flickr).
With post-processing, you can also do the following techniques:
Use the Brenizer method of shooting a "bokeh" panorama. Shooting a scene with a long fast prime in many frames, and then doing a panorama stitch has the effect of faking a larger format sensor. You can imitate medium format with a crop or full frame camera this way.
Use gradient masks and/or depth masks and blur to create the toy model effect in post. See: How to get a miniature effect on pictures without special equipment? and specialized software like DOF Pro.
If you want to increase this effect when making photos, then shoot on the longest focus end and with smallest possible aperture value (F number).
If you are talking about the post production, then in Photoshop you can use layer with gradient mask, copy the main layer, apply any blur filter to it, then use gradient for the mask. Here is the lesson for this technique. If you have a landscape shoot from the high point, then you can apply 2 gradients on top and on the bottom leaving the center of the image focused and sharp so that it looks like toy model.
Here's how to make the background as blurry as possible while keeping the subject sharp.
It’s the contrast between a sharp subject and a very blurry background that makes this effect stand out. Simply setting a wide aperture and getting a shallow depth of field is not how you get this effect, because then the subject may not be fully in focus. Background blur depends not just on the aperture setting, but also on the positioning of the camera, subject, and background, and on the the focal length of the lens.
First, decide how large the subject should appears within the frame. That's the magnification (relative to the frame size, ignoring differences between formats). The magnification is an important aspect of the composition that will probably override all other considerations for sharpness and blurriness, so this procedure assumes the relative magnification will be decided first and held constant.
Next, find the largest aperture (smallest f-number) that keeps the subject entirely in sharp focus. That means the focus field must be just deep enough to include the subject front-to-back, with nothing in front of or behind the subject in sharp focus. Focus must also be set accurately to include the entire subject. Note that the subject appearing sharp on a screen (or in a print) depends on how it is viewed. If you are viewing the image on a screen at reduced resolution or from a far distance, more of the image will appear sharp (that is, the focus field will be deeper). So try to emulate the final viewing conditions as best you can. If you want the image to appear sharp according to the limit of your camera's resolution, use your camera's focus magnification feature to zoom in all the way as you are adjusting the aperture and focus. For a given magnification and format, the focus field's depth depends largely on the f-number, and is largely independent of the distance between the camera and the subject, and the focal length. So with the aperture now set, it shouldn't require much adjustment from this point on. (Though with the subject very close to the camera and with a very wide lens, the focus field is deeper for a given f-number and format.)
With the magnification and the f-number now set and held constant, background blur is maximized by maximizing the camera-to-subject distance and the subject-to-background distance. Longer focal length lenses let you move the camera further from the subject and increase the background blur while maintaining the desired magnification.
Shooting indoors, where the camera-to-background distance is constrained, background blur is maximized by placing the camera as far as possible from the background, and placing the subject halfway in between. If your longest lens doesn't give you enough magnification, move the subject closer until you get the magnification you want.
Shooting outdoors where the distance to the background is large, use your longest lens and back the camera far enough away from the subject to achieve the desired magnification. A more distant background will appear blurrier, but the effect increases more slowly as the distance approaches infinity, so don't worry about trying to make the subject-to-background distance really large.
Note that moving the camera back also changes the perspective, making background objects appear larger relative to the subject.
A note about formats and lenses: If you are shooting with high magnification, the focus field will be shallow even at moderate f-numbers, and so having a fast lens is not important. In fact you might not be able to get the entire subject in focus even at the lens’s smallest aperture setting. Smaller format cameras have lenses with smaller apertures, which can overcome this problem. If you are shooting with low magnification (the subject is far away or the angle of view is wide), the focus field can be deeper than you want even with a fast lens. Larger format cameras can overcome this problem by having lenses with larger apertures.
Depth of Field (DOF), background blur, and bokeh are related, but different concepts. There is also subject-background isolation/separation.
Depth of field is based on focal length, aperture, distance, and a predefined acceptable sharpness level. It is concerned with what parts of the image are expected to be sharp, not what parts of the image will be blurry, or how blurry unsharp portions of the image will be.
Background blur – How blurry is the background? I think of it as something that can be quantified. How big are bokeh balls a given distance from the lens? Different lenses with the same focal lengths, apertures, and distances can create different, though similar, amounts of blur because of different amounts of distortion, aberration, and field curvature. (There's also foreground blur, but people tend to be less interested.)
Bokeh is a qualitative description of the blur that is produced. Are the bokeh balls round? Do they vary in shape throughout the frame? Are they smooth? Do they have edge highlights? Are they smeared? Some people refer to how lenses "render" images.
Subject-background isolation refers to (subjectively) how well the subject stands out from the background. This can be achieved with depth of field and background blur, as well as appropriate lighting (such as rim lighting and creative use of "glow"). The common formula is to try to use narrow depth of field with high background blur. However, some types of bokeh can achieve good subject isolation with high depth of field and low background blur. For instance, Sonnar lenses create bokeh balls with an edge highlight toward the center of the frame, but a smear toward the edge of the frame. This tends to emphasize the sharpness of the subject toward the center, while also emphasizing the blurriness of the background toward the periphery.
Depth of Field and Background Blur tend to be inversely related. To minimize DOF and maximize background blur:
You can also apply the 'Brenizer Method'. It is a hybrid solution that can produce outstanding shallow DOF images. See tutorial at ryanbrenizer.com. You still need post-processing though (and Photoshop works really well for this) to achieve final result.
The wider your aperture, the smaller your focal depth will be. So if you can shoot with a fast lens and use aperture priority to use the most open aperture setting possible you will increase this effect.
Assuming you have already taken the photo and everything is in focus, you can use software such as photoshop to select everything in the image you want to be blurry and apply a blurring filter. You can take it a step further and create an alpha layer to vary the amount of blur with the depth of the image. This will take longer but result in a very nice effect.
Apart from aperture and focal length, depth of field also decreases with camera-subject distance. So get you subject as close to the camera as possible.
There are also special lenses that don't actually have huge aperture, but that have bokeh that looks like they had. These are specifically engineered to blur the background.
The one of them I know is Sony 135mm f/2.8 [T/4.5] STF: http://www.photozone.de/sony-alpha-aps-c-lens-tests/390-sony_135_28
When fully open, the amount of light getting in equals to f/4.5 lens, but bokeh is like it was f/2.8.
You can find a little tool at http://howmuchblur.com which can give you some additional feeling for the subject. With this tool you can compare different lenses, cameras, and subject sizes and see a visual comparison between their ability to blur the background.
To a lesser extent:
...
Background blur has the "blur disk diameter" (also the size of specular highlight disks in aperture shape and distance far behind the subject) f/a where f is the actual focal length (not the effective one) and a is the aperture number, measured in the focus plane. Since it would be unusual for your subject not to be in the focus plane, this determines your background blur size in relation to the subject.
So basically use the longest focal length and the largest aperture. This will require you to move backwards solidly. Now here is the rub: while this does not affect the far distant blur size, stuff in vicinity of the subject then gets blurred proportionally less, eating up almost all of its focal length based blur.
So for stuff in vicinity to the subject, only increasing aperture will significantly increase blur, but with growing focal length, the blur of more distant objects will continue growing with the distance more than it would at shorter lengths.
Of course, increasing their relative distance can be done simply by increasing the absolute distance: make sure that you have lots of clear space behind the subject.
Bokeh is controlled by depth of field, the shallower the depth of field, the more bokeh effect you will get. So how do you get a shallow depth of field? The quickest way is to move the subject further away from the background. Combine that with a zoom lens, which moves you further away from the subject and you'll start to see more bokeh. The ideal way, however, is to purchase a lens with a larger aperture (think f/1.2 - f/1.8). If you shoot Nikon and are on a budget, I highly recommend the Nikon 50mm f/1.8D.
For shallower depth of field, increase the distance between the subject and the background. Greater the distance between your subject and the background, the greater will be the blurring effect - sharp subject.
