How to test your lenses

Quality lenses are more important than quality cameras. A sharp colorful photograph can be taken only with quality lenses, quality tripods, and for those using film cameras, quality films. That is if you also use good technique. I have had many people asking me about my camera brand when they see my pictures. They believe it is the camera that produces good pictures. No matter how sophisticated newer cameras are, they are still just a box that hold film flat during exposure. Even top of the line digital SLRs are still just tools for taking pictures. Pixels and storage devices have replaced films, but they have not replaced good photographic technique.  I'll give you an example. The sharpest lens I currently own is my Konica Minolta Maxxum 200mm f/2.8 APO lens. This lens is an extremely sharp medium telephoto lens. It obviously fits only Maxxum AF 35mm and digital SLR cameras, but if this lens could be fitted to all other manual focus or autofocus 35mm and digital SLR cameras made by other manufacturers, it would produce identical images. I bet my 200mm f/2.8 APO lens that you wouldn't be able to tell which camera produced which picture.

As you can see, sharp lenses are very important and you should buy the best you can afford. Before you buy a lens, if you can, run a test to check its quality. You can test your current lenses as well if you haven't done so already.


Left image: Canon EOS D-60, Tamron 70-210mm f-2.8 lens, 1/60sec at f-5.6, Bogen tripod and ball head.

If you are buying a new lens, take you tripod and load your camera with a slow ISO slide film and visit a well supplied camera store. Film cameras are better for testing lenses. You should use slide film for testing lenses even if you prefer print films or digital pictures. Slides are easier to evaluate than prints since you'll be looking at the original rather than second generation copy. You can test the lens outside the store (usually with the sales person watching) by photographing buildings, cars, or anything else you feel is a good test target. Shoot at every f-stop, and if you are buying a zoom, at all marked focal lengths. Take notes and compare results using a high quality 8X loupe on a light box, when you get your slides back from the lab. Do not project the image on a wall or scan the slide to view on your computer monitor. The quality of projector lens and the surface you use for projecting the image will always degrade image quality. Computer monitors won't show overall corner to corner sharpness either.


A good test target is your daily newspaper. This way you can read the current affairs while checking lens' sharpness.  Make sure the paper is flat and focus in the middle. Again, shoot at all f-stops. When you view the slides, check to see how clear the letters on the newspaper look. Check especially the corners. I have noticed that most lenses produce soft edges around the corners at larger apertures. All lenses however, are at their best when closed down two or three stops from open apertures. They begin to show loss of image quality at their smallest aperture due to diffraction. When you test one  lens, you obviously can't tell if the lens is sharper than another model. You need to compare different models.

 If you already own some lenses you want to test, don't worry about other lenses. Just test to see if your lenses are capable of producing images you want. If you get a chance to test similar lenses, compare focal lengths and f-stops. Not all lenses produce same results at any given focal length and f-stop. You may not be able to tell the difference between two lenses even with an 8X loupe. As a general guide, a good lens should produce quality 8X10 images at all f-stops. Many lenses are capable of even larger prints. You should do your own printing or use a quality lab to further test your lenses. I have found that more expensive lenses are always good. I yet to see a bad three thousand dollar lens. This is especially true with fixed focal telephoto lenses. I'm not too careful buying more expensive lenses! I just compare prices, features, and available accessories and buy the one I like and can afford. High priced Zooms or any zoom as well as shorter fixed focal length lenses concern me the most. They are not all equal. You can test them at your local camera store or rent them for a day. Renting a 300mm f-2.8 is expensive, but a pair of 28-85mm f-3.5-4.5 and a 75-300mm f-5.6 cost you 30 dollars for a weekend. For the price of a movie and popcorn for you and your date, you can test to see if spending $400 will buy you quality lenses. I'm sure your date will understand.

Photographic Lenses The camera lens determines, to a great extent, the quality of the image produced in any camera and must be a major consideration when selecting a camera and lens for serious work. This guide offers a complete, dedicated treatment of all types of lenses for all types of cameras, including digital. Explored in detail are the terminology of lenses, how different lens types function, the advantages and disadvantages of different types of lenses, and how the angle of view, aperture, shutter, and focusing abilities of a lens affect the photos taken with it. Photographers will also learn the basics of lens design, aspheric lens elements, retro focus lenses, shift control lenses, image stabilizers, and much more.