A general purpose lens is the most important and most-used lens in most photographers' kits. With a highly useful focal length range and a wide to moderately wide aperture, 24-70mm lenses can cover everyday needs, portraits, landscapes, cityscapes, food/travel and much more. Sony has two high-performing, 24-70mm constant max aperture zooms in its lineup – the FE 24-70mm f/2.8 GM and FE 24-70mm f/4 ZA OSS – and we're going to take a closer look at them to see which may be better suited to fill your general purpose needs.
Sony FE 24-70mm f/2.8 GM and Sony FE 24-70mm f/4 ZA OSS Shared Primary Features
Primary Advantages of the Sony FE 24-70mm f/2.8 GM Lens
Primary Advantages of the Sony FE 24-70mm f/4 ZA OSS Lens
Other Differences: Sony FE 24-70mm f/2.8 GM vs. Sony FE 24-70mm f/4 ZA OSS
Image Quality Differences: Sony FE 24-70mm f/2.8 GM vs. Sony FE 24-70mm f/4 ZA OSS
From a sharpness perspective, the "sharpest lens" title will depend on the specific aperture/focal length being compared. There isn't really a clear winner when the entire range of tests is taken into consideration. The FE 24-70mm f/2.8 GM shows slightly less vignetting at 24 & 70mm (vignetting is similar at the middle focal lengths) when the lenses are compared at their widest apertures.
When compared at f/4, the f/2.8 lens shows significantly less vignetting. The f/2.8 lens has less severe distortion over the zoom range (the difference is most noticeable at the lenses' widest and longest focal lengths), but most will prefer the f/4 lens' flare performance.
Who should opt for the Sony FE 24-70mm f/2.8 GM?
There are many drawbacks to an f/2.8 constant max aperture lens compared to an f/4 constant max aperture lens, including increased size, weight and cost. However, the Sony FE 24-70mm f/2.8 GM's twice-as-wide max aperture will allow you to freeze motion in half as much light at the same ISO setting compared to the FE 24-70mm f/4 ZA OSS. If you're a wedding/event photographer, or prefer not to pack a tripod for nighttime cityscape/street photography adventures, the increased size/weight/cost associated with the f/2.8 lens will prove more than worthwhile. Portrait photographers will also appreciate the better subject-to-background separation provided by the 1-stop wider aperture and the smoother bokeh/better starbursts created by its 9 bladed aperture (vs. 7).
Who should opt for the Sony FE 24-70mm f/4 ZA OSS?
If you don't often need to capture moving subjects in low-light situations, and can tolerate higher ISO use when the need arises, then the Sony FE 24-70mm f/4 ZA OSS offers many of the benefits of the Sony FE 24-70mm f/2.8 GM at less than half the price. For static subjects, when combined with Sony alpha-series cameras' IBIS (In-Body Image Stabilization), the Sony FE 24-70mm f/4 ZA's Optical SteadyShot should provide even more effective stabilization compared to a lens without built-in IS.
As you can see by the product pictures and specs listed above, the size and weight differences between these two lenses are substantial. Photographers who will benefit from the FE 24-70mm f/4 ZA OSS's smaller size/lighter weight include anyone carrying their gear for long periods of time (for backpacking, vacations, long events, etc.) and those wanting to pack more gear in a similar amount of space.
With many full frame Sony a-series cameras having built-in sensor stabilization, one of the Sony FE 24-70mm f/4 ZA OSS Lens's major benefits – optical stabilization – is diminished. However, it does have a few advantages remaining over the Sony FE 24-70mm f/2.8 GM that aid in boosting the f/4 lens' popularity – smaller size, lighter weight and a much lower cost. If any of those features is a priority for you, then the Sony FE 24-70mm f/4 ZA OSS is the lens to get. Otherwise, a 24-70mm f/2.8 zoom has been a must-have lens for a wide variety of professional photographers over the years, and for those choosing Sony gear, the FE 24-70mm f/2.8 GM is one of the first lenses they'll be adding to their kits.