DOF andBOKEH
By Diane Bohlen
Most of the time when we take a photo we expect everything from foreground to background to be in sharp focus. Cameras, however, are not capable of having everything equally in focus and so we make compromises. Our cameras have little boxes superimposed on the viewing screen that we are supposed to put over the most important part or subject of the photo so the camera knows where to put the sharpest focus.
If you are shooting a landscape with flowers in the foreground, meadows in the middle, and mountains in the background and you want everything in focus you choose a wide angle lens and you choose a small aperture, (which actually is a large number, like f/22). This will give you the sharpest focus possible throughout the picture.
Sometimes, however, you want a limited DOF. For example, when you are doing portraits, you want the person to be in sharp focus, and the background to be a soft blur so that your subject stands out.
To have a shallow DOF you would choose a telephoto lens and a wide aperture (which is a small number, like f/4). This will put objects in front of your subject and behind your subject in a soft blur, while your focus point or subject will be sharp.
When you want to be creative, you can also use DOF to make an interesting picture that is different than what you would normally see.
The photos I took where everyone was in focus seemed too busy. I didn't know where the subject was. When I blurred the background, this photo became more interesting. You can see the boys playing in the background but leaves it to your imagination to decide what they are doing. Chase is clearly the subject, watching his brothers, and you can just imagine him saying, "I want to be bigger so I can play, too."
A celebrity was sitting in the same row as me so I leaned forward and focused on her so she would be the main subject, while everyone else was softly faded in the background.
The following information was found on the internet from various photographers.
How Sensor size affects DOF
The physical dimension of the sensor in your camera affects DOF. Unlike the other variables, it’s not possible for you to change, unless you use a different camera.
Small sensors, such as in phones and compact cameras, give you the most DOF. This is one main reason people upgrade from a phone to a camera. Because they are not able to achieve a shallow depth of field with their phone.
Phone manufacturers are trying to mimic shallow DOF in various ways. But as yet it appears to be little more than a poor gimmick. There is no substitute for size..
Larger sensors in DSLR and mirrorless cameras have made them popular with video producers. This is because of their capacity for shallow DOF. Traditional video cameras contain small sensors so therefore generally have deeper DOF.
How aperture affects DOF
The aperture is an adjustable opening within a lens. The primary function is one of the controls used to control the amount of light entering the camera. A narrow aperture setting lets in less light than a wider setting. The settings are measured in f-stops.
Adjusting the aperture setting, (changing the f-stop value,) not only controls the amount of light entering, but also the DOF. Changing the aperture is the most common way photographers choose to control DOF. The wider aperture the shallower the DOF. So the lower f-stop number you choose (eg. f/1.4), the less of your image will be acceptably sharp. Choosing a narrower aperture, a higher f-stop number (eg. f/22), will render more of your photo in focus.
Lenses are made with differing maximum apertures. Typically a kit lens will have a widest aperture value of f/3.5 when the lens is zoomed to its widest focal length. This value changes the more you zoom in. So the widest f-stop at the longest focal length may only be f/6.3. Prime lenses usually have a wider maximum aperture. This is why they are often favored by photographers who like creating photos with a shallower DOF. Popular 50mm lenses have f-stop settings of f/1.8, f/1.4 or even wider.
How lens focal length affects (apparent) DOF
The longer focal length lens you use the shallower the DOF appears. But it doesn’t actually change.
If you take photos of the same subject with two different focal length lenses, the images made with the wider lens appear to have a deeper DOF. The aperture should remain constant. When you crop the image made with the wider field of view, so the elements in the images are the same size, you will see no real difference.
How Distance from Camera to Subject affects DOF
Changing the distance between your camera and the subject is another way to affect the depth of field. To increase the depth of field, just move back. To reduce it, move closer. Your camera works exactly like your eyes, becoming more focused as it gets closer to the subject.
Of course, changing your distance will also change your composition. To fix this problem, you can change the lens or focal length to maintain the composition you want.
How can you see the DOF when composing a photo?
Cameras with digital viewfinders or monitors will display the DOF as it will appear in the photo. Because of the small size, it can be difficult to see clearly unless you zoom in.
Cameras such as DSLRs with optical viewfinders will not allow you to see the effect of the DOF unless you use the DOF preview button.
Bokeh
Bokeh—from the Japanese ‘boke’, meaning ‘blur’ or ‘haze’—is the blurring or more precisely the aesthetic quality of the blurring of a photograph. Blurring is achieved by using a shallow depth of field. It can be used to create a number of striking light effects or simply to highlight a subject by keeping the rest of an image out of focus.
The Difference Between DOF and Bokeh
A shallow depth of field refers to the object or subject being in focus, but the areas in front, and especially in the background, are blurred. Whereas bokeh is the term that refers to the aspect of light sources that are blurred in the background or foreground.
Getting Started
Blurry backgrounds are nothing new when it comes to photography. The technique of blurring the background to emphasize a subject in the foreground has been used by photographers for decades, and by painters and other visual artists for hundreds of years. Now thanks to the proliferation of digital cameras this phenomenon has exploded in recent times.
Many people like photos with a tack-sharp subject and a smooth blurry background, and even though some might say it’s more of an over-used trend, the truth is that bokeh is here to stay. The trick to using it effectively, is to learn how to use the physical properties of lenses and light to create the look you are going for. While some people turn to creative editing tricks like adding blurry filters or doing Photoshop gymnastics there really is no substitute for the genuine article. If this is something you have always wondered about or wanted to try for yourself, here are four easy steps to get you started.
1 – Shoot with a wide aperture
Take a look at the front of your lens, you will probably see a few numbers that look like 1:3.5-5.6, or 1:2.8, or f/4 (read: What the Numbers on your Lens Mean for more on how to find this). These numbers refer to the size of the aperture in the lens itself, and how big the opening can get. Ironically smaller numbers are bigger, and a lens that says 1:2.8 will be able to let in much more light than a lens that says 1:4 or f/4. (Some manufacturers use different schemes to show the aperture size but it’s always the number after the colon, or on the second side of the / that you want to look for when determining the maximum size of the lens opening.)
The smaller the number, the wider your aperture will be, and the less light you will need to take a properly exposed photo. Wide apertures also mean your photos will have a shallower depth of field, and anything out of focus behind your subject will begin to take on a smoother, more visually pleasing blur. In other words, wide apertures help give you more bokeh.
If you’re itching to get some pictures with the same kind of buttery-smooth background blur you have seen in nature magazines or fashion spreads, put your camera in Aperture Priority mode (on Nikon) or Av (Canon, Pentax, etc.) It helps if you have a prime lens that doesn’t zoom in and out, since they usually have wider maximum apertures, but even a kit lens can give you decent results if you have enough light.
2 – Put your subject far away from the background
If you have been trying to get the kind of silky, blurry bokeh you seem to notice in everyone else’s photos you might try this one simple trick and you won’t believe what happens! Simply putting a great deal of distance between your subject and whatever is behind it, can go a long way towards creating the bokeh you have always dreamed about.
If you are shooting portraits, try moving your subjects to a location where there is a great deal of space behind them, or even just repositioning yourself so you are looking at your subjects from a different angle that puts more distance between them and the background.
3 – Get close to your subject
As mentioned in the opening paragraph there are many different optical elements that come into play when dealing with bokeh and background blur, and certainly shooting with wide apertures while putting a great deal of distance between your subject and the background are critical elements of the equation. Another thing you can do, is position your camera and lens physically close to the subject you are shooting. Combine this technique with the first two, and you’re virtually guaranteed to get good results.
4 – Zoom in
If you are trying to get bokeh shots and not having much luck, there’s another technique that could mean the difference between frustration and celebration. Due to how lenses collect, and focus incoming light rays, it’s easier to get blurry backgrounds with longer focal lengths. This is why these types of shots are difficult to get on mobile phones, which generally have lenses with a much wider angle of view. Grab your nearest camera, whether it’s a DSLR or a humble little point-and-shoot, and zoom the lens as far in as it will go. Now use the other tips I have already mentioned: set the aperture to the widest setting, find a subject that’s relatively close to you, and make sure there is plenty of room between the subject and the background.
Many beginning photographers always push for the lowest aperture available. This is a mistake. Often, the blurry portion of the photo is more aesthetically pleasing if enough detail is left in the background to make out some shapes or objects. The first rule to better bokeh is to determine proper depth-of-field rather than always choosing the blurriest background available.
25 baby foot Beth
Often, the most captivating photographs are those which do something that the viewer did not anticipate. Relating the sharp foreground subject of an image with something in the blurry portion of the image can create a truly creative image. You’ve probably seen this effect in wedding photography when a bride is close to the camera and in sharp focus, with the groom blurry in the background. This technique is even stronger when the foreground not only relates to the background, but when it interacts with it.
Two Types of Bokeh
The first is geometric bokeh. Geometric bokeh is out of focus highlights that actually take on a geometric shape. This particular shape depends on the nature of the lens, but circles, hexagons, heptagons, and octagons are all fairly common.
The second type of bokeh is creamy bokeh. This is the smooth, out-of-focus look that photographers often strive to achieve.
Impressive geometric bokeh is created by highlights. One way to get strong geometric bokeh is to look for bright lights in the background.
You can achieve this in a few ways. For instance, you might look for objects that filter sunlight, such as leaves. They break up the rays of the sun and turns them into small pinpricks of light that then become impressive geometric bokeh.
You can also look for elements that reflect light. Water is a great option. Another is water droplets. Areas that are wet with morning dew can generate beautiful bokeh when placed behind the subject.
30 droplets Paul Van Allen
Third, you might search for small light sources in the background. Car lights, street lamps, or christmas lights all work well, especially when shooting after sunset
One setting in which bokeh photography is particularly effective is in a city at night. The rush of lights and the glare of the streets can be captured with greater atmosphere when you let a little blur into the frame. Blurring is also a great way of expressing movement in photography, allowing you to portray the busy nature of the cityscape and the buzz of cosmopolitan life by night.
Fourth, if you really want to create bokeh but are struggling to find the proper conditions, you can create them yourself. Bring a string of fairy lights with you when you’re shooting, and place them behind the subject.
Here is a method of generating stunning bokeh, it can produce amazing creamy bokeh when used one way, and amazing geometric bokeh when reversed.
Both ways involve making sure that your subject is in the shade. Both methods also involve having a bright background. Ideally, you should be shooting in the early morning or late evening when the sun is low in the sky
Where the techniques diverge is in the placement of the sun.
If you shoot with strong frontlighting—that is, if the sun comes from behind you, over your shoulder—position your subject so that beautiful golden light spills onto the background behind your subject (while your subject remains shaded).
Then that golden light will often render the background similarly golden, and you’ll find that your bokeh becomes wonderful and creamy.
Whether you choose to shoot with frontlighting or backlighting, by placing your subject in the shade and working during the “golden hours” of sunrise and sunset, you’ll generate beautiful bokeh
Going Further:
Once you’ve mastered the basic techniques behind bokeh, you’ll soon find which kinds of background and subject matter best suit your style. You can take the technique further by making your own lenses to play with specific shapes and lighting conditions.
Bokeh background or El Bokeh Wall
El Bokeh Wall is basically a technique in which you can capture a photo with the backdrop full of bokeh, which makes your photo eye-catching.
Step 1
Take a sheet of aluminium foil long enough to fully cover the background in your frame. Now crumple the foil sheet gently and make a ball out of it, but do not press it too hard.
Step 2
Now open the foil ball that you just made and in doing so, make sure that you do not remove the crumples. These crumples on the aluminium foil sheet will be used to create the bokeh effect.
Simply lay the sheet on a flat surface and move your hand gently over it, without removing the wrinkles formed on the foil sheet.
Step 3
Once you have flattened the aluminium foil sheet, put it on the wall or hang it in such a manner that it fills the frame. Make sure that the crumples are evenly distributed and the sheet fills your entire frame in order to capture perfect results.
Step 4
Now place your subject in such a position that there is a gap of at least 2-3 feet between the foil sheet and the subject. This will allow you to capture shallow depth of field and make the background out of focus. In order to create a bokeh effect you need to allow some distance between the subject and the background.
Step 5
The last step is where you light up your subject and the foil sheet in order to create a well-lit photo. Start with lighting the aluminium foil sheet, you can either use a flash, studio light or even a table lamp. In order to make the bokeh appear colorful, you can place a colored gel in front of the light source.
Now light up the subject as per your desire. Make sure that the light source being used on the subject does not spill too much on the background which can make your background appear overexposed. This is another reason why you should maintain some distance from the background.
On a smartphone, depth of field and bokeh work differently. The elements needed are processing power and the right software. The smartphone camera needs to recognize the foreground and background of a photo, and then blur the background, while keeping the foreground in focus. So rather than occurring when the photo is snapped, smartphone bokeh is created after the picture is taken.
Remember that bokeh is an effect that can be used to produce a range of different aesthetics; it’s not restricted to certain kinds of subject matter.
You can use bokeh with subjects ranging from fall leaves and macro flowers to small toys and Christmas trees. Try it out, and you’ll see how versatile it can be!
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