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Testing Your Own Gear is a Great Idea

By Wayne Cosshall 

How can you take great images when you don’t fully understand your own equipment? Let’s look at how to go about this and why.

You might think, “I read all the reviews before I bought my gear, so why should I test it as well?”

There are some things you need to understand about equipment testing:
  • Many reviews are simply not very good;
  • Lab reviews may not reflect your shooting conditions;
  • Even field reviews may not reflect your usage;
  • Equipment varies enormously.
Many reviews are just plain no good. The people doing them may not really understand photography or even what they are doing. The review may be rushed. Many people writing reviews of cameras and lenses are not photographers (or not very good ones).

Reviews done purely in the lab or the office (as many are) will not reflect real shooting conditions in the field. Every photographer uses their gear differently, so your particular usage may give quite different results.

When a magazine (print or online) does a review they almost always get only one lens or camera of a particular model to test. Almost all camera equipment (with the exception of some German lenses) is manufactured using the concept of tolerances. So if a lens element is supposed to have a focal length of 200mm, it may be manufactured with a focal length tolerance of 2%.  What this means is that the actual focal length of the lens element may be anywhere from 196mm to 204mm. If all other lens elements have the same tolerance figure, then in a lens with five to eight elements the overall optical design can vary significantly. The same idea of tolerance applies to mechanical components, electronic components, etc. The result is that significant variations from body to body and lens to lens can exist on the same production line. So the lens you get, for example, can be anywhere from exceptionally good to exceptionally bad and still fall within the manufacturer’s tolerance values. 

By doing your own testing you will discover exactly how it performs, for you, in the conditions in which you actually shoot, and in the way you actually use it.

Let’s look at how to test a camera body and a lens.

Testing Camera Bodies: With camera bodies we are interested in testing two main things: image noise and vibration profile.

To test image noise, shoot multiple sequences at each ISO setting of the subjects and in the lighting conditions you typically use. Why does this matter? Because the perception of noise varies greatly depending on whether the subject has broad areas of smooth tone or lots of detail, and on the overall lightness of the subject matter (noise is more obvious in darker than lighter areas). Put the camera on a tripod, start at the lowest ISO setting and shoot two sequences at each ISO setting, one with noise-reduction on and the other off (make sure you know which is which). Evaluate the results zoomed to 100% in various parts of the image.  Then determine the maximum ISO that you can accept for different light levels and subjects. You can also decide whether the camera’s noise reduction gives you a better result or not.

To test vibration, you again want the camera on a tripod. Use a long-ish lens and frame on some subject with a lot of detail. Use the highest ISO and an aperture to give you a shutter speed of around 1/30 or 1/60 of a second, in aperture priority. Use a cable release or the self-timer. Steadily shoot while reducing the ISO so you get a sequence of shots at the same aperture. Then evaluate the sharpness in the center of the image when zoomed to 100%. What you should find is that there will be a certain shutter speed (or several speeds) at which there is noticeably less sharpness.  This means you have found the shutter speeds at which mirror slap (in a SLR) and/or shutter movement vibration has lowered the image sharpness. If you don’t find this, try again at a range of shutter speeds higher or lower than you were using. Continue to use the same aperture in order to avoid introducing new variables that could affect the accuracy of the test.

Testing Lenses: With lenses we are interested in determining the sharpest aperture and how sharpness varies by focal length with zoom lenses.

To determine the sharpness characteristics, set up the camera on a tripod pointing at a scene that has a lot of detail, all at roughly the same distance and covering the frame from edge to edge. Use a cable release or self-timer to shoot a sequence of shots at each aperture and focal length. Use the ISO to make sure you avoid any problem shutter speeds that you determined earlier. Examine the center and corner of the images at 100%. Determine which aperture gives the sharpest result and if there are any that are so blurred you consider them unacceptable. You will also see how the sharpness varies by aperture. If you are a numbers type of person you can shoot resolution charts, but I find many photographers prefer to actually see how the sharpness varies on a subject they are familiar with.

You can use similar approaches to test other gear. For example, test your flash for evenness of coverage by shooting a white or even-colored wall at various zoom settings.

Once you know how your own gear actually performs you will know which apertures, focal lengths, lenses, ISO settings and shutter speeds you prefer. You will also have fewer negative surprises as you examine the results of your shooting.

Happy testing and happy shooting!

 

Posted 03-19-2009 1:18 AM by Eileen Fritsch
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