Sigma AF 105mm f/2.8 EX DG macro (Nikon mount) - Review / Lab Test Report - Analysis
Lens Reviews - Nikon / Nikkor (APS-C)
Article Index
Introduction
Analysis

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Distortion

As to be expected from a fix-focal lens and especially for a macro lens the level of distortion is quite negligible.

The chart above has a real-world size of about 120x80cm.

Vignetting

On the Nikon D200 with its reduced (APS-C) image format the (full format) lens exhibits very little vignetting at f/2.8 and from f/4 & up the issue is absolutely negligible.

MTF (resolution)

Typical for most macro lenses the Sigma AF 105mm f/2.8 EX DG macro performed great in the MTF lab. The lens is already excellent in the center at wide-open aperture with marginally worse corners. The peak performance is reached at around f/5.6 with an excellent center and border quality. As usual diffraction is the limiting factor at smaller aperture settings. Extremely small apertures such as f/32 should be avoided due to very pronounced softness. The tested sample showed a slightly uneven resolution distribution.

Please note that the MTF results are not directly comparable across the different systems!

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

Chromatic Aberrations (CAs)

The Sigma shows an exceptionally low degree of chromatic aberrations (color shadows at harsh contrast transitions) which are negligible in field conditions.

Verdict

The Sigma AF 105mm f/2.8 EX DG macro is an excellent lens without any significant optical flaws. The resolution figures are excellent and neither distortions nor CAs nor vignetting is something to worry about. Similar to the Tamron or Tokina counterpart it is basically as good as the much higher priced Micro-Nikkor (the classic one, not the VR). The build quality feels very good although the implementation of the Dual-Focus mechanism isn't really perfect.

Regarding all the excellent lens alternatives in this segment it is quite difficult to select a favorite ... but the good news is that there isn't really a wrong choice.

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