How to check when buying a lens - main features

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Today before buying Optics many are interested in the question of how to check when purchasing a lens.Indeed, the need to take seriously in the process.For each system, and digital cameras, there are dozens of different variants of lenses on the market, ranging from a modest $ 50 to $ 10 000 (for example: a telephoto lens Canon).Figuring out your needs - it is the first step to buying lenses.We need to clearly decide what you will shoot.Ask yourself questions like the following ... - Should I shoot indoors or outdoors?- Do I have to take pictures of fast moving objects (eg, sport)?- Do I want to shoot portraits or making a wedding?- Do I like to shoot wild animals and nature?- Doing shots of landscapes, architecture or interiors?These are questions that you should ask yourself, and decide on its own budget.If you plan to buy a digital SLR (DSLR), then, as part of a bundle, you will already have the basic lens, which makes it a pretty good pictures.However, the main attraction of this type of camera is the ability to switch lenses to get the best shot in any situation.The important question: how do you find the right one for your needs?

Understanding glass

Before you check when purchasing a lens, should understand what makes one lens and how it differs from the other, it is first necessary to be familiar with a few basic concepts.Focal length, technically speaking - this is the lens focal length, represented in millimeters, which is the distance between the back of the lens to the focal plane, where the parallel rays of light entering the lens to converge at a point.It is important for you, because the focal length determines the angle of the lens.The smaller the focal length, the wider the field of view.When you zoom in, the field of vision narrows, so you get less of the object that looks larger in relation to the environment.In the world of conventional 35mm film, the focal lengths of 16 mm to 35 mm, are generally considered wide angle.50-mm lens called "normal", because these lenses are very close to the human eye, and anything above 100 mm, it is considered telephoto.However, the focal length of a little more complicated when it comes to DSLRs.This is because the camera image sensors, less than 35mm film, so they cut off part of the picture and give the effect of a longer focal length.To get an idea of ​​how it will affect the divergence angle of the lens, it is necessary to multiply the crop of digital cameras.Nikon D40, for example, has a crop factor of 1.5 x.As a result, 35-mm lens has a field of view equivalent to 52mm when placed on the D40.

Aperture

Another key component of how to check when buying a lens, a diaphragm.This aperture is a mechanism that controls the amount of light that passes through the lens of the image sensor.The diaphragm usually called in terms of F-stops, and represent a number such as f / 2.8.The smaller the number, the larger the hole, and the more light that enters the chamber.The lens of the camera, which opens a wide aperture, allows you to maintain a faster shutter speed in low light conditions.This can be essential to obtain a sharp image with a handheld camera.Wider apertures also provide greater creative freedom, allowing you to throw the background out of focus.Before you check out when buying a lens, check with a good understanding people, as store employees are not always competent in these matters.Thus, you can save your time and money.