Basic DSLR Training Camera Lenses
In this Basic DSLR Training Camera Lenses we are going to look at why a lens is important. I know without one you can’t take a picture. The camera lens allows the photographer to see and compose the shot they want to take.
It’s important to remember that all lenses are not equal; you get what you pay for. The more you pay the better the quality of the lens. You require the prime lens, those with a red ring around the front of the lens. Prime Lenses are made from glass which offers the best clarity.
If you’re buying a camera with a pop up flash, the lens that usually comes with the camera will probably be a kit lens.
Kit lenses are not the best quality. They are fine for taking snaps, but if you are going to consider anything else then upgrade the lens when you buy.
Lenses come in a variety of sizes and focal lengths. You have lenses for macro (close up work), wide angle (good for landscape work), standard lens (approx. 50mm) this sees what the eye is seeing, telephoto for taking photos of subjects that far away and bringing them closer. Lenses start as wide angle and move through to telephoto from 10mm (or smaller) through to 400mm or larger. The measurement is not the size of the physical lens but what is called the focal length.
This is the distance in mm from the optical centre of a lens to a point where a subject at infinity appears in sharp focus – usually the surface of a piece of film or a digital camera’s sensor. Think of this as the physical length of a lens in very simple terms.
What lens do I need to have?
Ask what photographs you want to take. Is it landscape, people, insects or maybe aviation? The subject dictates the lens you may need to use; one lens does not fit all. For landscape you might require a wide angle lens, for people a normal to telephoto lens, for insects a macro lens and aviation a long telephoto lens.
Have a look at this info graphic from digital camera. This shows the angle that the lens will take in from wide angle to telephoto. You will see a wide angle means width of the image but the subject in the distance appears small. To a telephoto where the angle of view is small but the subject appears closer in the image.
Simply put Aperture is about the amount of light that is let in by a lens. This happens because the lens has a diaphragm. To let lots of light in, the diaphragm is wide open and to restrict light it closes to a small hole. The confusing bit for a beginner is that when it is wide open, the aperture is referred to as a small f number (i.e. f2.8) and when closed it is referred to as a large number (i.e. f22). You can see this on the left hand side of the chart below.
Lenses of f2.8 or lower are considered to be fast lenses. This means they will allow more light in when being used in low light conditions.
You will have heard photographers refer to f numbers when referring to lenses. As you can see from this chart from N-Photo magazine, you have Full Stops, ½ stops and 1/3 stops. A full stop means that the aperture changes by either halving in size or doubling in size depending whether you are allowing less light in or more light in. The ½ and 1/3 stops are increments within the full stops and adjust light in in small changes.
It is also worth remembering that the aperture works in conjunction with the ISO and Shutter Speed. Change one and the others change as well.
Depth of Field.
One of the spinoffs from changing the aperture is the depth of field or in plain terms “what is in focus” in the image. With a large f number (f16 or larger) the majority of the image will be in focus. With a small f number (f4.0 of lower) when you focus on the subject you will notice that the background is soft or out of focus.
Basic DSLR Training Camera Lenses looks at how the lens works and the different effect they can create by changing the aperture. A camera is a wonderful device to create beautiful images. By experimenting with the various modes you can create a different image. You can have an image that the majority is in focus or to a soft background around your subject. It’s yours to play with and experiment.
Using the aperture setting, set your cameras WB to suit the lighting conditions i.e. Sun symbol for sunny day and set an ISO of 100. Ask a friend to pose for you and experiment by changing the aperture settings through f22 down to the lowest setting you have. Make sure you focus on the subject and take an image at each setting.
Download your images onto a PC. Look at your images, if you can side by side or slideshow them. Can you see the difference of what is in focus?
What to do next
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