Conclusion

The Sony FE 40mm F2.5 G is a tiny, lightweight moderate wide-angle prime lens with a premium finish and feel. Its main selling points are its rather unique angle of view, excellent build quality, retro feel, tiny size and weight, and fast auto-focusing.

This lens is a great performer optically, being pin-sharp throughout virtually all of the frame, even when shooting wide-open at f/2.5.

Vignetting is a little heavy wide-open, but chromatic aberrations and barrel distortion are well-controlled in both the JPG and Raw files and the bokeh is nice enough for what is after all only a f/2.5 maximum aperture lens.

A traditional aperture ring is a feature that we love on any lens, and Sony's implementation of it on the 40mm F2.5 G is nigh on perfect.

It has a lovely action, positive movements between the 1/3rd aperture stops, and a pronounced gap between f/22 and the Auto setting that requires more pressure to move so that you can't inadvertently select it.

It also gets one up on its main rivals, the Sigma 35mm F2 DG DN and Sigma 45mm F2.8 DG DN, by offering a dedicated switch on the lens barrel that allows you to de-click the aperture ring for video use, making it more suited to movie-making than the Sigma alternative.

This lens' most obvious rival, the Sigma 35mm F2 DG DN, has the main advantage of offering even better build quality and also a faster maximum aperture, but for once the third-party alternative is similarly priced to the Sony option.

The Sony 40mm F2.5 is smaller and lighter than the Sigma and offers a better designed lens hood plus extra features like the de-clickable aperture ring and the focus hold button.

The Sony also beats the Sigma when it comes to auto-focusing, with a dual motor linear auto-focus system that is silent, very quick, and virtually 100% reliable.

It's perhaps not fair on either lens to compare them directly though - after all, the Sony FE 40mm offers a subtle yet uniquely different view of the world that means that it has few true rivals - indeed, the manual-focus Voigtlander 40mm f1.2 Nokton Aspherical, pricey Zeiss Batis 40mm f/2 and the huge Sigma 40mm F1.4 DG HSM are the only other 40mm lenses available for Sony Alpha full-frame cameras.

In summary, the FE 40mm F2.5 G is our favourite out of the three small, retro lenses that Sony released all at the same time. While the FE 24mm F2.8 G and FE 50mm F2.5 G are also excellent lenses in their own right, the novel 40mm focal length gives this one the edge, both against its siblings and other similar primes.

Ratings (out of 5)
Design	5
Features	5
Ease-of-use	4.5
Image quality	4.5
Value for money	4