Nikon AF-S DX Micro 40mm f/2.8G review

The DX format Nikon AF-S DX Micro 40mm f/2.8G is wonderfully compact and lightweight, ideal for popping into a spare corner of your camera bag in case you need it. That might happen more often than you think, as it’s very versatile. The focal length and aperture rating make it a good standard prime for general shooting, with the option of quick shutter speeds under dull lighting and a fairly tight depth of field.

Specifications

Mount: Nikon F
Full frame: No
Autofocus: Yes
Stabilization: No
Lens construction: 9 elements in 7 groups
Angle of view: 38.8 degrees
Diaphragm blades: 7
Minimum aperture: f/22
Minimum focusing distance: 0.163m
Maximum magnification ratio: 1.0x
Filter size: 52mm
Dimensions: 69x65mm
Weight: 235g

Key features

The key feature of any macro lens is its ability to take extreme close-ups. This little DX format lens delivers full 1.0x macro magnification at its shortest focus distance of 16.3cm, as measured from the focal plane of the camera. Like most macro lenses, it also has a fairly fast aperture rating of f/2.8, although narrow apertures are generally preferred for macro shooting, so you can gain even a tiny amount of depth of field.

The lens is nicely made and has a ring-type ultrasonic autofocus system, with the usual manual override, so you can adjust the focus distance without needing to switch to manual focus mode. It also features a 7-blade aperture diaphragm. Both autofocus and camera-controlled aperture adjustments are compatible with all Nikon DX format DSLRs.

Performance

Image quality is excellent and the lens works fine for general shooting. Macro shooting is rather more tricky, as the inner barrel extends at shorter focus distances, giving a working distance between the front of the lens and the subject of just 3.5cm in full macro mode. This can make it difficult to photograph bugs without scaring them away in the process, and can also cast a shadow over the subject, blocking ambient light. Autofocus speed is rather pedestrian and manual focusing lacks smoothness and precision for extreme close-ups.

Lab results

We run a range of lab tests under controlled conditions, using the Imatest Master testing suite. Photos of test charts are taken across the range of apertures and zooms (where available), then analyzed for sharpness, distortion and chromatic aberrations.

We use Imatest SFR (spatial frequency response) charts and analysis software to plot lens resolution at the center of the image frame, corners and mid-point distances, across the range of aperture settings and, with zoom lenses, at four different focal lengths. The tests also measure distortion and color fringing (chromatic aberration).

Sharpness:

Sharpness is really impressive across the whole image frame, apart from mediocre corner-sharpness at f/2.8.

Fringing:

Colour fringing can be noticeable when uncorrected in-camera at wide apertures but are very minimal at medium to narrow apertures.

Distortion: 0.01

The 40mm Micro is essentially a distortion-free lens with a practically perfect lab score.

Verdict

Built for Nikon DX (APS-C) format DSLRs, this lens works well for general shooting, with an effective focal length of 60mm in full-frame terms. However, despite delivering full 1.0x magnification at its shortest focus distance, it’s less than ideal for serious macro photography. The working distance between the front of the lens and the subject is uncomfortably short at less than 1.5 inches and the focus ring lacks precision for fine manual adjustments.

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