The Sigma 28-70mm f/2.8 EX DG Lens features a fast, fixed 9-blade aperture ranging from f/2.8 to f/22. Again, you probably will want to avoid f/2.8 over most of the focal length range. A 67mm filter diameter keeps the Sigma 28-70's objective end reasonably small. Not many lenses share this filter diameter (the Canon EF 70-200mm f/4 L USM Lens
Free Newsletter. View the image quality delivered by the Canon EF 24-70mm f/2.8L II USM Lens using ISO 12233 Resolution Chart lab test results. Compare the image quality of this lens with other lenses.
Verdict. The Canon EF 24-70mm f/4 USM L IS is a difficult being with a great technical performance and a worrisome focus characterstic. It is certainly capable of delivering a image quality that sometimes even surpasses its bigger in-house mate (EF 24-70mm f/2.8 USM L II). It is very sharp throughout the range with no significant weakness at The Bottom Line. The Canon RF 70-200mm F4 L IS USM is a compact zoom with quick focus and exquisite optics. Pros may still want a F2.8 zoom, but this is more than enough lens for most photographers. Verdict. Canon RF 24-70mm f/2.8L IS USM Performance. At 24mm, central sharpness is excellent from f/2.8 to f/16 and still very good at f/22. The edges are excellent from f/2.8 to f/11 and very 4EwH.