Canon EF 24-105mm f/4 USM L IS - Review / Lab Test Report - Analysis
Lens Reviews - Canon EOS (APS-C)
Article Index
Introduction
Analysis

Distortion

At 24mm the lens exhibits pronounced barrel distortion (1.8%) which is significantly more compared to the EF 24-70mm f/2.8 USM L. From 40mm and up there is slight pincushion distortion but nothing to worry about under most field conditions.

24mm:

40mm:

70mm:

105mm:

The chart above has a real-world size of about 120x80cm. Possibly expect more distortions towards closer focus distances.

Vignetting

On APS-C DSLRs vignetting is very well controlled with the lens. Wide-open vignetting does not exceed ~0.5EV which is usually not much of an issue in real life situations. One stop down the problem is absolutely negligible.

MTF (resolution)

The lens produced very good to excellent resolution figures under lab conditions. On an APS-C DSLR the performance is best between 24mm and 70mm where the center resolution is truely excellent throughout the tested aperture range. The borders follow closely behind with very good figures at f/4 and also excellent results beyond. At 105mm there's a slight decrease in quality down to a very good center and good+ boders at f/4. Stopping down helps to boost quality but the local peak quality isn't reached prior of f/11. All-in-all this is a very impressive performance for a 4.4x zoom lens.

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

Chromatic aberrations (color shadows at harsh contrast transitions) can be a problem at 24mm where the average width exceeds 1.5 pixel at the image border at wide open aperture. Stopping down helps to reduce the issue but it remains less than stellar here. To a lesser degree this remains true at 40mm at large aperture settings. Towards the tele range the CA are pretty low and nothing to worry about.

Verdict

Regarding its equivalent zoom range (39-168mm) on an APS-C DSLR the Canon EF 24-105mm f/4 USM L IS may not be the most sexy lens here but its performance figures are very impressive nonetheless. In fact the resolution results beat those from the EF 24-70mm f/2.8 USM L and match the EF 28-70mm f/2.8 USM L with its much more conservative zoom range (but higher speed). There's a slight decrease in performance at 105mm but even here the quality remains on a very high level. As to be expected from a modern Canon L lens the construction quality is up to pro standards matching its fasters cousins. The lower price tag plus the extra IS should compensate the slightly more moderate max. aperture for most users. Is it a perfect lens then ? Well, there're also downsides like pronounced barrel distortions and higher than expected CAs at the wide-end of the zoom range. However, the package remains extremely attractive if you can live with the rather unattractive zoom range on an APS-C DSLR - similar to other 28-xx or 24-xx zooms this lens is really more meant for 1.3x or FF (D)SLRs.

Optical Quality:    
Mechanical Quality:
Price/Performance:
      
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