The Nikon AF-S DX 40mm f/2.8G is an impressive macro lens which offers genuine 1:1 macro capability
The lens feels very light on account of its largely plastic construction but that is not necessarily a bad thing. The mounting plate is metal and surrounded by a rubber flange that provides a certain level of protection against dust and moisture. The focusing ring, meanwhile, is well placed towards the front of the lens and has a good, albeit slightly heavy, feel.
Despite the absence of any such indication in the model name, the lens benefits from an internal focusing mechanism that leaves the focusing ring undisturbed in AF mode and also permits on-demand manual intervention. Nevertheless, many photographers prefer to use pure manual focusing when working close-up and will therefore to set the mode switch to MF.
For general-purpose use the lens is fitted with a distance-limiter switch, which prevents the lens from hunting below 0.2m. This is important because one weakness is the lens’s slow focusing speed ‚ a surprise given the Silent Wave Motor (SWM) drive.
Technical testing revealed a hint of chromatic aberration across the aperture range on high-contrast technical targets visible on account of the macro’s very high sharpness. The 40mm’s MTF curve remains at or above 0.3 cycles-per-pixel right across the aperture range except when the lens is fully stopped-down to f/22, where there is such a sharp loss of sharpness that critical users will simply shun this setting.
Real-world testing produced excellent results. When small-scale objects were photographed multiple times in AF mode some images were found to be slightly sharper than others ‚ which is why macro specialists often opt for manual focusing.