With shooting photos of farther away objects at low contrast, the proper focus is often not so easy to fix, no matter whether focusing manually or automatically.

Using a zoom lens at wideangle position brings you close to the temptation to zoom in to the most important detail for more accurate focusing. After focussing you twist back to the desired wide-angle position.

Stop-Off-Back! Never make the focusing in this way.

Especially universal zooms, covering both the wide-angle to telephoto, move the point of right focus during zooming. Consequently, the above-mentioned “Zoom-To-Sharpen” technique leads to significantly fuzzier images. So the focus should be the last step before pressing the shutter button.

I tested this regard in the photo studio with two similar zoom lenses (Canon 24-105mm and Sigma 18-125mm) and came to the same results in both cases: By zooming out the focus point moves to the back, as this excerpt magnification of the same shooting situation, such as included above, but in wide angle position, with no more changes in focus setting is shown.

For the checks I used this gear: