Learning Center
How to Buy A Lens

Try these tests yourself before you buy a lens. We think that once you evaluate and compare the results you'll join many professionals who choose Tamron. The clincher comes when you factor in one more important consideration: Value. Of the handful of fine lenses available today, no one gives you more performance for your money than Tamron.

Looking into a quality lens is like looking into a dark well filled with clear water; deep and dark, with no internal reflections. This appearance is the result of careful finishing, state-of-the art multi-coatings, and blackening of all reflective surfaces including the edges of lens elements. It’s one of the most important factors in lens performance, because stray light reflections detract from picture quality.

With the lens focus set at minimum distance (if the lens is a zoom, set both the focusing and zooming rings to bring the maximum number of elements into a forward position), angle the lens slightly to reflect the room lights. Count the number of colors you see. Three or less means the manufacturer has reduced the number of costly and time-consuming multiple layer coatings, which are necessary for superior light transmission and accurate color balance. Both sides of every element in each Tamron lens are multicoated with Tamron's patented BBAR (Broad Band Anti-Reflection) multi-coatings to assure optimum image quality.

Turn the control rings over their entire range from end-to-end. Focus and zoom action should be silky smooth, with no play, looseness or binding. The action of the zoom ring in particular should be well damped and hold its position well. Diaphragm click-stops should be positive, with no slippage. Any problems encountered in this test mean awkwardness in use, and are an indication of poor machining and assembly.

Now mount the lens on your camera and see how it feels. The manual focus ring should be wide enough to grasp easily and securely and the lens should be well balanced and, compact enough to work in some of the tight spaces you may find yourself in.

Check the maximum aperture. It's not only important for light-gathering power, it also determines the brightness and clarity of your focusing screen under low-light conditions, and can affect focusing accuracy when focusing manually. For example, an f/2.8 lens transmits twice the light than an f/4.0 lens, and lenses with apertures smaller than f/5.6 may be difficult to focus manually, especially in dim light.

Check the minimum aperture as well. If you're using higher ISO settings such as ISO 800 and 1600, you'll need to stop down to f/22 or f/32 in some daylight situations or risk over-exposure. Small f-stops like f/22 or f/32 also provide the best depth of field. Working at long telephoto focal lengths in the 200mm or greater range requires very small aperture settings to ensure good depth of field.

The manual focus ring should operate smoothly and hold their settings well. Lenses with aperture rings should lock at their minimum aperture when using the AE Program mode to prevent accidental incorrect exposures. If the lens is a push-pull zoom (not too common with newer lenses) point the lens upwards and downwards to be sure the zoom ring doesn't slip; it should stay in place.

Check that the lens you are considering provides continuous focus from the normal distance range settings right down to the macro settings. In real life, you usually don't have time to take your eye away from the viewfinder to focus on a close-up subject. Note that the very best lenses will provide full zoom action even at macro distances, a great convenience.

Most photographers ultimately invest a lot more in their lenses than in their cameras. Even weekend enthusiasts use a variety of different lenses for different shooting situations. So it's a good idea to protect your investment in lenses by making sure they have superior quality optics that will stand you in good stead for the long haul.

Fine lenses are built to be rugged and reliable. A good indication of just how rugged they are is how long the manufacturer warranties them. Top optical companies such as Tamron provide the longest warranties in the business.