Learning Center
How to Buy A Lens

Try these tests yourself before you buy a lens. We think that you'll join many professionals who choose Tamron. Especially when you add one more important test: 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 black, with no internal reflections. It's the result of careful finish, one of the most important factors in lens performance, because stray light reflections detract from picture quality.

With focus at minimum distance (if zoom, set to bring the maximum number of elements forward), 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) multicoatings.

Work the controls end-to-end. Focus and zoom should be silky smooth, with no play, looseness or binding. Diaphragm click-stops should be positive, with no slippage. Any problems mean awkwardness in use, or 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 the lens should be 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 determines the usefulness of your focusing screen under low-light conditions when manually focusing. For example, an F/2.5 lens transmits 25% more light than an F/2.8.

Check the minimum aperture as well. If you're using higher speed film, you'll need to stop down to F/22 or F/32 in some situations or risk over-exposure. Small f-stops like F/22 or F/32 also provide the best depth of field. Working with a long telephoto lens requires very small aperture settings to ensure good depth of field.

The manual focus ring should have good torque and lenses with aperture rings should lock at minimum aperture for the AE program mode to prevent accidental incorrect exposures. If the lens is a push-pull zoom, point the lens up and down to be sure the zoom ring doesn't slip, it should stay in place.

Check for continuous focus from normal focal range settings right down to macro. In real life, you usually don't have time to take your eye away from the viewfinder. (the very best lenses will give you full zoom action in macro, too)

Most photographers ultimately invest in a lot more lenses than cameras. Even weekend enthusiasts use 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.

Fine lenses are built to be rugged and reliable. A good indication of just how rugged they are is by how long the manufacturer warranties them.