This article is part of a larger series on lens buying options.

Scenario: Wildlife photography on a shoestring

Mark’s story:

Mark contacted me with a difficult task.
Mark is a photo enthusiast who upgraded his Canon S2 to his first D-SLR, a Canon XTi. The XTi is an excellent choice and apparently, he got a good deal on it, too.
Mark lives in Alaska and always enjoyed the great range of his S2 (432mm equivalent) to capture wildlife.

What we considered:

Since his XTi already came with a kit lens, we focused on the most reach for the money. A 300mm lens gives him an equivalent focal length of 480mm due to the XTi’s 1.6 crop factor.

Budget Lenses can be good

Hunting for budget lenses is often a hit and miss game. You will always be happy with an L-Lens if you can afford it, but even a cheaper lens can give you excellent results.
Cheap lenses often vary significantly within the same model. It is important to find a store with an excellent return policy, even if it is slightly more expensive. Most photographers obsess about lens built quality to the extend that they completely neglect the optical qualities of a lens. Even a lens with lots of plastic can take great pictures.
Affordable lenses often just have a wider spread, due to cheap quality control. Within the lot, there are always good ones.

Image Stabilization/ Wide Aperture

Both are extremely desirable but may be outside your budget. With an equivalent focal length of 480mm (300mm * 1.6), a shutter speed of 1/500s or faster is required for handheld shooting. You can only get these speeds in bright daylight. With image stabilization, you could gain 2 stops (1/125s) or more (1/60s), making it easier to shoot wildlife in undergrowth or dim light, when the animals are most active.
affordable IS lens If you cannot get these speeds, you have to stabilize your camera (tripod, monopod, gorillapod) or you have to increase the ISO sensitivity of your camera (check my Exposure Series).

Mark’s decision:

Mark decided to buy the 70-300mm USM Canon Lens. Without Image stabilization it costs less than $200 on Amazon (IS costs $500).
The lens is an excellent value. Having this much reach will go a very long way towards better wildlife shots.
Mark was able to put together a system that will enable him to take excellent outdoor shots without breaking the bank.
Often it is more important to get maximum reach than having Image Stabilization. With today’s cameras, even a photograph captured with an ISO setting of 800 will look excellent when enlarged. Noise is less visible on prints than it is on your screen.

Scenario: One Lens that does everything

Maureen’s story:

Maureen picked up a Canon 450D with the kit lens. She wants to travel with her camera and take great pictures. She is not quite happy with the reach of the kit lens.

What we considered:

Many people feel uncomfortable having to change lenses on their SLR cameras. Dust can enter the camera and will eventually become visible in the pictures. Cleaning the sensor yourself is not something everyone is comfortable with either. It is nothing to be afraid of, but the camera manufacturers do not support it and some claim that it voids warranty. Do not fall for this. They have no way of knowing that you cleaned your sensor if you use the brush method. Do not use solvents though, as they may smudge.

Superzoom Lenses:

A superzoom is a zoom lens with a very large zoom range. If you do not wish to change your lens frequently, but you also require a very large range for a variety of situations, a superzoom lens is your solution.
Lens makers try to beat each other with ever-greater range; although I doubt that this is useful, especially since image quality starts to deteriorate. It is similar to the megapixel race that did not improve camera quality at all. Tamron just announced a new lens (18-270mm). If you really think you need this much range, you should reconsider if you really cannot change lenses in the field.

Kit Lens only:

Another alternative is to go with the Kit Lens alone. I would guess that about 80% of your shots would end up in the 18-55mm range. Since this still means that you will miss about every fifth shot, it is not really an option I would consider. The Kit Lens is great for indoor photography and for less threatening looks. A small lens intimidates less; a feature candid street photographers greatly appreciate.

My recommendation

Maureens lens of choiceI think Maureen could be very happy with the Sigma 18-200mm OS. I recently bought this lens for Dani and she is very happy with it. Although the lens is slow (f/6.3 at the long end), it has image stabilization and therefore, easily makes up for its slowness with plenty of margin. The Sigma lens has surprised me with an optical quality that is very good for a lens of such a tremendous zoom range.

Alternative:

You could go with the Canon 55-200mm f/4-5.6 IS. The lens is a bit faster than the sigma, features image stabilization as well, and is probably supposed to be the ultimate companion for your Kit Lens. On the down side, you still need to be able to switch lenses.
People who bought the Nikon 18-200mm seem to be thrilled with its performance. If you are the proud owner of a Nikon camera, this may be a better alternative over the Sigma lens.

Testing lenses

Cheaper lenses need to be tested and possibly returned until you find a good one. I would normally look for front- or back focusing and for image sharpness in the corners.

Testing for Front Focus and Back Focus

Some lenses focus in front or behind of the actual focal point. I have only experienced this with third party lenses, but it can happen with all lenses.
Put a coin on the table and set your camera to use only the center focus point. Use your lens at minimum aperture (to minimize Depth of Field) and take a few shots of the coin. Then look at the pictures with 100% magnification on your screen to determine if the coin is the sharpest part of the image (where you put your focus). If the area in front or behind the coin is sharpest, you may have an issue and need some more testing.
Perform this test at different focal lengths if you have a zoom lens.
Do not forget to select all focus points again after this test is complete.
I always put my camera back to “normal” settings, because I sometimes forget to check when I head out for a shoot.

Testing Image Sharpness

Your lens will be sharpest at around f/8 in the middle of its zoom range. If you cannot get the lens reasonably sharp even at the corners of your image, there maybe something wrong with it.
Cheaper Lenses will lose sharpness towards the corners of the image at wide apertures. That is quite normal. This is the reason why you often hear people referring to “stopping a lens down,” which is the process of setting a smaller aperture than the maximum. Decreasing aperture about two stops often increases sharpness quite dramatically.
Take pictures at all apertures and focal lengths and review them at 100% magnification to get a good feeling of your lens.
You will also notice sharpness to decrease at smaller apertures (e.g. f/22). Diffraction (light bending) is to blame.