Even when you break it down to the simplest terms, the relationship between aperture and depth of field can seem confusing. Whenever I teach a class, or try to explain the manual settings on a friend's camera, this is the always topic we have to go over again and again. The good news is that with practice and concentration, the aperture/depth of field relationship will finally 'click' for you. The bad news is, there is more to understanding depth of field than just using your aperture.
But let's start at the beginning. What is depth of field?
In simple terms, the depth of field is the area behind and in front of your main point of focus, that is also acceptably in focus. So if you focus on a subject one metre away, you might look at your photo and find that everything from 0.9 to 1.2 metres is in focus. In this case, your depth of field is 0.3 metres (30 centimetres).
The very first thing a new photographer learns about depth of field is that it is controlled by the aperture on your lens. Very simply, a smaller aperture creates a larger depth of field, and a larger aperture creates a narrower depth of field. So if we go back to our previous example, let's say the 30cm depth of field was captured with an aperture of F-8. You could narrow the depth of field considerably by adjusting the aperture to F-2.8, a much wider setting.
Sound confusing? It is hard to explain it any more simply, especially without showing you photos as examples. If this is your first time working with depth of field, don't worry. Go outside right now and take some shots just as I have described, and you should be able to see the results right away.
So if it is that simple, why do so many people struggle with depth of field? As I wrote earlier, there is more to depth of field than just the aperture.
Depth of field is also affected by how close the subject appears in your photo. That means either how close you are to the subject, or how much you magnify or reduce the subject using different sized lenses.
The closer you are to your subject, or the closer you make the subject appear by zooming in with your lens, the smaller the depth of field becomes. Let's say you are photographing a person five metres away. At this distance, a standard or wide-angle lens will not only show a lot of background, but the wide depth of field could make the background quite distracting. However, if you walk much closer to the subject and re-focus, the depth of field will become much smaller. As a result, the well-focused person will stand out clearly from a blurry background. You can maximize the effect by opening the aperture to its widest setting.
Now imagine your subject is posing in front of a beautiful waterfall. If you stand close to the subject and photograph them with a wide aperture, you could get a great shot of the person but the waterfall will be an out of focus blur. You could improve the situation slightly by closing the aperture a few stops. However, the most effective way to improve the depth of field is to stand a few metres further back, and/or zoom back to a wider angle with your lens. Not only will you capture more of the background, but it will be much sharper than if you only adjusted your aperture alone.
So there you have a quick look at not one, but three factors than can make it easier to master depth of field; aperture, distance from the subject, and the size of the lens. This really is a topic that needs to be illustrated with a few photos, but hey - you have a digital camera. Why not go and try out these ideas at the next opportunity? It won't cost you anything, and you can see the results right away. You will soon develop a feel for the best way to make depth of field work for different subjects in your photography.
One creative photography tip that's used by photographers is Depth of Field. Depth of field refers to how much of your photo is in sharp focus compared to how much is in a softer focus or blurred.
Ideally, our subject is always in sharp focus. The eyes particularly have to be in sharp focus if our subject has them. Eye sharpness is absolutely critical when doing portrait work, so be sure to check on your auto-focus. Often it has not locked on to the eye area, but more often the nose since it protrudes from the face of man and beast.
Most point-and-shoot cameras are designed with a small lens aperture (opening) to allow everything in the scene to be in focus. However, the DSLR cameras have a lens which will let you choose the size of the lens opening. Generally, the larger aperture opening, the smaller the depth of field. Meaning, only a small portion of your image, the part you consciously focus on, will be in sharp focus while the rest of the scene will be in a softer focus or blurred.
Apertures are designated as f-stops. f4.5 is a much LARGER lens opening than say f16. F16 might be a good small aperture for keeping everything in a landscape scene in focus. The larger lens opening of f4.5 would provide the smaller D.O.F. (depth of field) more appropriate for a portraits.
This DOF effect can be multiplied when using a zoom lens. As you move from a 50mm lens to a longer 200mm lens, and increase your distance from the subject, your depth of field grows even smaller.
A smaller depth of field is a great way to separate your subject from the background. This makes him or her stand out, almost in a 3D effect, which is why a great many portraits are created this way. It also works well for photographing wildlife. Or scenes where you're stuck with just an awful background.
Experience and practice are the best ways to gain a better understanding of the proper settings you need to get the best shot possible.
One of the more apparent differences between film and digital video is the way the cameras handle depth of field. Film cameras have allow for a shallow depth of field (resulting in only the subject area being is in focus), while video cameras offer a larger depth of field (resulting in everything being in focus). To achieve a shallow depth of field with digital video camcorders a depth of field adapter is generally used. Before you rush out to purchase an adapter you should ask yourself if you really need one.
Before you decide if you need one, you have to understand exactly what you are purchasing. A depth of field adapter is not a quick solution. It will not provide perfect results once you install it. They are a tool like any piece of video equipment in your arsenal. This tool, like any, requires mastering. It will take time and practice to achieve the results desired from an adapter. With that said and adapter should not be an impulse by nor one you should rush to buy/build. I will say for most videographers it is a fun tool to experiment with.
Ok, so you decided you want to go for an adapter. The first thing you should do is research. They're are many high-end commercial solution that cost $1000+, however there are also as many 'DIY" versions on the market ($150+) and tutorials for building your own DIY adapter. I can say i have seen footage from many of the 'DIY' adapters and they can be very comparable, if not superior, to commercial solutions. This is why research is the key. You can search sites like Vimeo.com for HD footage from most of the adapters out there. There are also many comparison videos there as well. While researching adapters keep in mind that there are 3 types of adapters; static, spinning, and vibrating. Static is fine, but you run into trouble with keeping the internal ground glass(heart of the adapter) clean, which results in noticeable artifacts and patterns in your footage. The solution is to add movement to the ground glass...hence the vibrating and spinning adapters. Spinning adapter are larger and use a rotating disc as the ground glass, this can actually cause a 'pumping' focus effect if not aligned correctly. Vibrating adapters are my personal choice. They actually vibrate the ground glass, usually in a slight circular, pattern. The vibration is very slight, but enough to make any dirt on the ground glass disappear. Usually vibrating adapter allow for speed adjustment which provides you with even more control.
Okay so you decided you want an adapter and you understand the basics of each type, now what? Now you decide if you want to attempt to build on yourself or purchase one. Purchasing a DIY vibrating adapter will run you at least $250 (most likely more), while a commercial version will be at least 3x as much. Building your own sounds like a cheap route to go right? Well, not exactly. Unless you have the parts available to you at a local store (most likely not) you will probably end up sourcing them online. And you can find great prices online, however, since there really isn't a one-stop shop for parts, you have to factor in shipping. Which really ranges greatly from store to store. This will make a vibrating DIY adapter about $100 - 200 easy. However there are a few creative solutions utilizing PVC pipe and other easy to get parts from local stores. Tutorials for these can be found at here.
I hope this helps, also don't forget to figure in lens support and a tripod into your budget...once you start experimenting with the actual adapter you will understand why these might be needed.
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Depth of field is the distance that is acceptably sharp within your photograph and varies depending on these three elements:
- aperture focusing
- distance lens
- focal length
There isn't a sudden change from sharp to unsharp but the change occurs gradually with everything in front of the focusing distance and everything to the back of the focusing distance losing sharpness. The first element to consider is the aperture and how wide this should be when the shutter is fired. A wide aperture (small f-stop) will give a shallow depth of field while a small aperture (large f-stop) will increase the depth of field. So when shooting a landscape and you want as much in focus as possible you may want to set your aperture at f22, for example, to give maximum focus, whereas if you are photographing a portrait and you want to separate the subject from the background you might shoot at f1.8 to push the background out of focus by using a narrow depth of field. When setting your aperture you must also take into account the light levels as your shutter speed will also change. Your shutter speed will decrease with a small aperture, possibly necessitating the use of a tripod. Your shutter speed will increase with a large aperture, possibly to the point where underexposure occurs and you have to consider changing your ISO level or using neutral density filters.
Distance from the subject is an important aspect of depth of field control. Generally, the closer you are to your subject the narrower the depth of field at whatever aperture is used. The further you are from the subject, the larger the amount of focus. This combined with lens choice are further aspects to consider when controlling depth of field. Depth of field varies depending on lens focal length and even lens manufacturer. Wide angle lenses give a greater depth of field while longer lenses give a narrower depth of field. Landscape photographers generally use wide angle lenses and small apertures to gain a maximum amount of focus while portrait photographers use longer lenses and larger apertures enabling separation of the subject and background.
As you can see there are a few elements to consider when controlling depth of field and how it will affect your photographs. The three main elements are aperture, focal distance and focal length. Learning about depth of field and how it affects your photographs will give you control in determining whether your background or foreground will be sharply in focus or blurred.
The best way to gain knowledge in photography is to take photographs and experiment. There are always rules of thumb and in general with depth of field the larger the aperture (small f-stop) the less in focus and the smaller the aperture (large f-stop), the more in focus.
Gregor Menzies is a photographer and designer with experience in various areas from scientific photography and poster design, portrait and wedding photography and a passion for landscape photography. Have a look at
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