Nikon D7100 Optics

Zoom
Good performance with the 18-105mm VR kit lens.

The Nikon D7100 is available with a Nikkor AF-S DX 18-105mm f/3.5-5.6G ED VR (Vibration Reduction) lens, which has a better-than-average zoom ratio of about 5.8x for a kit lens. Sharpness was very good across most of the frame at full wide angle in our Far-field shot, though there's some blurring in the extreme corners and a hint of flare. There were low levels of coma distortion in the leaves at the corners, and chromatic aberration wasn't an issue because most of it is removed by the D7100's image processor (see below). Performance at 34mm was likewise quite good with only a touch of blurring in the corners. Results at full telephoto were better than average showing good detail near the center of the frame, though the periphery was a bit soft and not as contrasty. Again, chromatic aberration was well suppressed. (These shots were both taken at f/8. See below for how the lens performs at maximum aperture.) Overall, a good performance for a kit lens, and the built-in Vibration Reduction (Nikon's term for optical image stabilization) will come in handy for hand-held shots in low light.

Macro
A larger-than-average macro area, with soft detail overall. Flash throttles down well.

The Nikon D7100 captured a larger-than-average macro area with the standard 18-105mm kit lens, measuring 4.29 x 2.86 inches (109 x 73 millimeters). Detail was somewhat soft, and there was strong blurring in the corners. (Most lenses have some softening in the corners at macro distances.) Some vignetting is noticeable in the extreme corners as well. The Nikon D7100's flash throttled down for the macro area well, producing a good exposure.

Geometric Distortion
High levels of geometric distortion at wide angle and telephoto ends with the 18-105mm kit lens.

The Nikon D7100's 18-105mm kit lens produced about 1.1 percent barrel distortion at wide angle, which is higher than average and noticeable in some of its images. At the telephoto end, pincushion distortion was 0.7%, also higher than average and noticeable in some images. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide-angle) or inward (like a pincushion -- usually at telephoto).

Auto Distortion Control
Low geometric distortion when Auto Distortion Control is enabled.

The Nikon D7100 offers an Auto Distortion Control feature to reduce geometric distortion automatically with most recent Nikkor lenses. As you can see it worked reasonably well with the 18-105mm lens, reducing barrel at wide angle and pincushion distortion at telephoto significantly, though some of the image was cropped away in the process. Since this option is database driven, it's only available for Nikkor D and G-type lenses with certain optics such as Fisheye and Perspective Control lenses excepted. Auto Distortion Control is Off by default.

You can also apply Auto or Manual Distortion Control to JPEGs after the fact, in the Retouch menu. Manual mode works with images from any lens.

Chromatic Aberration and Corner Sharpness
Very low to moderately low C.A. in JPEGs, much higher in uncorrected RAW files. Some corners are soft at wide angle and telephoto with the kit lens.

Chromatic Aberration. Chromatic aberration was moderately low at the full wide angle setting of the 18-105mm VR kit lens, suppressed by the D7100's image processor. (See below for crops from uncorrected RAW files.) At telephoto, chromatic aberration was even lower and hardly detectable. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.)

Corner Sharpness. The Nikon D7100's 18-105mm VR kit lens produced slightly soft corners at full wide angle when wide-open, but performance here is actually pretty good. The top corners were slightly softer than the bottom, and some of the softness likely stems from C.A. suppression. Softness didn't extend very far in the frames, though, and the center was fairly sharp. At full telephoto, all four corners were also somewhat soft, with the upper left being the softest, but the lens is softer overall at telephoto than at wide angle.

Corner Shading. There's some moderate corner shading ("vignetting") at both ends of the zoom when wide-open, as indicated by the darker corner crops.

f/8. Stopped-down to an aperture of f/8, corner performance did improve at wide angle, while sharpness in the center also improved slightly. Corners were still a bit soft at telephoto, however, as was the center. Vignetting was negligible.

Uncorrected RAW
Much higher levels of C.A. at wide angle and telephoto from uncorrected RAW files.

As you can see from the crops above comparing camera JPEGs (left) to uncorrected RAW files (taken at f/8), levels of lateral chromatic aberration are much higher in uncorrected RAW files, particularly at wide angle. The D7100's processor is doing a good job at suppressing lateral chromatic aberration in JPEGs.

Coverage
Very good accuracy from both the optical viewfinder and LCD monitor.

The Nikon D7100's optical viewfinder showed just over 99 percent coverage with our reference Sigma 70mm f/2.8 macro lens, which is quite good. In Live View mode, the Nikon D7100's LCD monitor showed closer to 100% coverage.