Strongest feature of a SLR/DSLR camera is its ability to change lenses. Entry level DSLR’s provide 18-55mm kit lens with camera body. In other cases, you’ll need to buy lenses separately.  Different types of lenses are expert on different ability. Wide angel lenses are used for Landscape, Nature photos; Normal range lenses are used for Portrait, Street photography. Telephoto lenses are used for wildlife, sports and outdoor portraits etc.

Photo By Harshit Sekhon

Different types of photography genre require different ability in lens. Landscape and nature require sharpness, Portraits need nice bokeh, Sports and wildlife need fast focusing speed, low light photography need fast aperture etc.

If you are planning to buy a new or used lens, its better to check the ability and specialization of the lens. It will help you to buy the appropriate lens for your purpose.

Zoom VS Prime Lens A zoom les is always helpful and nice attraction. It will be difficult to find a photographer who didn’t used a zoom lens. Most of the pro photographers prefer prime lens for their work. Well it doesn’t mean they don’t like or don’t use Zoom lens. The main difference is Zoom provides you the freedom of focal length and Prime give you more sharpness and color contrast. For details of Zoom VS Prime lens, visit the post Zoom VS Prime Lens. Become sure on your requirement of focal length freedom, Sharpness, Contrast. If you think you can’t pay more for different focal lengths by buying multiple prime lenses, go for a nice zoom lens. If Sharpness, Color Contrast is your priority, go for Prime lens.

Sharpness: Sharpness of A zoom lens can very easily in different focal length. Typically in long range zoom lens, the longest end doesn’t product good result in case of sharpness. But this is not an obvious. Sigma 50-500/ Sigma 150-500, Nikon 18-200 is known to produce fine result in longest end. It will be better for you to check the sharpness in maximum possible focal lengths before you buy.

Aperture: A fast lens means a lens with large aperture. Aperture is the gate for light in your DSLR. If you are a low light photographer or you need a large aperture, than go for 1.4, 1.8, 2.8 aperture lenses. If low light is not your concern, then you don’t need to pay much for a large aperture.

Focus Speed: A fast lens doesn’t ensure fast focus always. Modern Canon lenses use USM (UltraSonic Motor), Nikon use SWM (Silent Wave Motor) but in Lens it is marked as AF-S (Autofocus-Silent), Sigma use HSM (Hyper Sonic Motor) and Temron use USD (Ultrasonic Silent Drive) technology for fast focusing speed.

Taken from Wikipedia

Chromatic aberration (CA) Chromatic aberration is an issue which happens when a lens fails to bring all wavelengths of color to a focus at the same point. When chromatic aberration occurs, objects can appear blurred, and halos and streaks of color may appear in the image.

There are two types of chromatic aberration: longitudinal and lateral, also known as transverse. The good news is, it is easily recoverable in Photoshop, Lightroom or with other editing software.

Check in lens review sites if your chosen lens have CA problem or not. If yes, how much it is and can you accept it.

Famous Review sites are: DPReview.com, Ken Rockwell (Specially for Nikon), Canon Lens Reviews, The-Digital-Picture.com etc

Example from Wikipedia

Distortion A perfect lens would render straight lines as straight, no matter where they occur. Most practical lenses aren’t that good, though, and instead bend lines outwards (barrel distortion) or inwards (pincushion distortion). Wide-angle lenses and wide-range zoom lenses often suffer particularly badly from this. Wide angel lens produce more distortion rather than telephoto lens. Check how much distortion your chosen lens produce.

If you are purchasing a used lens, then check if the lens has any fungus in front or rear elements. Check if there any scratch in the lens. If it’s a zoom lens, check if auto focus works on every focal length.

Well this is not the full checklist and there might be any item unknown to me. If you have any tips to share, share in comment.

Related Posts:

1. Know DSLR Lenses – Part 2 | Zoom Lens VS Prime Lens
2. Know DSLR Lenses – Part 1 | Types of Lenses
3. Know DSLR Lenses – Part 3 | Variable VS Fixed aperture Lens
4. Best Portrait Photography Lens for amateur photographers