For an easier understanding of what this means it should read Depth of Focus in my opinion.Basically it means how much of the pic is in focus from front to back.This can be controlled in two ways, aperture control and focal length.The aperture is adjusted by means of a dial and is a set of blades designed to close and open inside the lens and acts like the iris in your eye.The smaller the aperture blades are closed then the more DOF you will get in the pic and vice versa.The settings on the camera are given as `f` stops.The smaller the `f` stop number then the wider the aperture and the shallower the DOF will be.For example an aperture of `F 5.6` will have a much shallower DOF than an aperture of say `F 22`.This can be used in two ways.For landscape work where a wide DOF is needed then use a small aperture (large f number) and focus about one third into the scene to ensure everything is in focus.For portrait work use a larger aperture (small f number) for a shallow DOF to isolate your subject from the background.
Focal length also has an effect on your DOF with small wide angle lenses having a much wider DOF than large primes and zooms.A lens of say 18mm focal length will only need to be stopped down to around `F 10` to ensure front to back focus (see pic below) but a long focal length of say 100mm will need to be stopped down to about `F32`.
This is exactly the same as when film was used and your choice of film depended on its use.You used a high iso film for sports (iso 400+) to freeze the action and a low iso film (iso 50) for landscapes to capture fine detail.Digital cameras record the image on a light sensitive sensor pretty much exactly the same as film and the sensitivity to light is adjusted via the iso settings on your camera.If you are working in bright conditions then use a low iso (iso100) to capture fine details.In low light conditions or to freeze movement then use a high iso setting (iso 400+).High iso settings are not without its problems and in place of grain in the days of film you get `noise`which are tiny blobs that are more noticeable the higher iso you use.
This is a method of photography mainly used in Sports,particularly Motor Sport.All you do is lock the focus point onto the subject and follow it with a smooth motion shooting as you go.Obviously this only works when the subject is moving in front of you from left to right or vise versa.It gives a sense of speed as the subject will be sharp but the background blurred as you can see in the pic below.This method can also be used in Wildlife Photography but as the running Animal or flying Bird can change direction at any time its a lot harder.
This is how long the sensor in the camera is exposed to light and is determind by the shutter speed used.A fast shutter speed will expose the sensor for a minimum amount of time freezing any action whereas a slow shutter speed will blur it.In certain situations the exposure can be used to a great effect.One of the more obvious situations is blurring the flowing water of a river by using a slow shutter speed.To get this effect you need to select the least sensitive iso (100) and a small aperture (F16).Also to get a fast shutter speed to freeze say a flying bird you will need to select a sensitive iso (400+) and a wider aperture.The shot below shows a bit of a `cliche`shot as nearly all landscape photographers have done it somewhere along the way.It is also remarkably easy to achieve.First chose your location and visit on a cloudy/overcast day.Sunny conditions will make it way too contrasty and very difficult to get the right shutter speed for the effect.Chose your viewpoint and set up your camera and tripod ensuring that you dont include the sky in your shot as it will just burn out.Set your camera to 100 iso in Manual Mode and select an aperture of about f10 or lower depending on the focal length used.I would suggest spot metering and taking the reading from a mid tone part of the scene (in the shot below the brown patch to the left of the main falls).Dial in the shutter speed given which will ensure that the shot will have an even exposure throughout with little or no burnout on the water.Then after focussing and composing the shot either use a cable release or self timer to trip the shutter and you should get something similar to the shot below.
This usually occurs at longer focal lengths or when a slow shutter speed is used and will result in blurred pics.When using zoom or large prime lenses say of 300mm or above then any movement by you will be magnified resulting in camera shake.This needs to be counteracted by using either a fast shutter speed,a support such as a tripod or an image stabalised lens.These lenses are usually more expensive than their counterparts but will allow slower shutter speeds to be used as they use small motors to compensate for any movement by you.Also you can eliminate camera shake by using a fast shutter speed but this method still needs a steady hand when using powerful lenses.
This term usually applies to landscape photography.Basically it is splitting the pic into thirds from either top to bottom or left to right.The thirds in landscape format are usually the bottom third being the foreground (a rock,river,plants or tree etc),the middle third being the landscape (mountains,fields,etc) and the top third being the sky.This isnt a set rule that has to be followed of course but is a start point for successful landscape photography.The example below shows the sunlit rock and foreground frosty grass as the bottom third.The hills beyond as the middle and the sky as the top third giving an equal balance to the photo.
This is another photography term mainly used in landscapes.It can also be used in urban photography to the same effect.All it means is using an element in the image (a river, road, wall etc) to `take` the eye through the photograph hence the name `Lead in Line`.This not only helps the viewer explore the whole pic but gives the photo a sense of depth and less two dimensional.Wide angle lenses are great for this as they accentuate the effect when done correctly.
This method of photography is becoming more popular as it can eliminate the use of graduated filters and the problems that can arise when using them.Basically HDR,or High Dynamic Range,is how much difference there is between the brightest part of the pic to the darkest in a high contrast scene.Modern camera sensors have a very limited Dynamic Range compared with the human eye so to get the pic looking the same as you saw it through your eyes needs a bit of help.This is where the HDR technique comes in.
The scene below is an example of where the image needed HDR to get it looking as I saw it through my eyes.The camera couldnt expose for both the sky and the ground in one shot as the difference in brightness between them would be too much Dynamic Range for it to cope with.What you do is set up your camera on a tripod and lock it down tight after composing the shot.Then set your camera to manual and take a shot using an exposure for the sky.This will mean that the ground will be black and underexposed (pic 1).Then take another shot but with the exposure set for the ground.This will then show the sky to be burned out (pic 2).The idea is to then `blend` both shots together giving an equal exposure (pic 3).This can be done in various HDR programme software or even in some of the menus in Photoshop.The alternative to this technique on this particular shot would be to use a hard edged grad filter.This would have held back the sky but would also darken the buildings that break the skyline,the HDR does not do that and gives a much more natural looking result.