Lens testing is fun and informative. While it won’t turn you into a Cartier-Bresson, it will have a visible impact on your photography too: if you understand the way your lenses behave, you’ll be able to make the most of them under all circumstances. For example, you might have one lens that you know to work well across the entire aperture range, and another that’s otherwise OK but starts to break down wide-open at maximum tele. Knowing this, you could make the intelligent decision to use the first lens wide-open for a shorter shutter speed, to minimize camera shake — but stop down the second lens, risking camera shake to get rid of the lens softness, or bumping up the ISO a notch, knowing that the added noise will hurt less than the lens softness.
Helderberg Photographic Society 