In 2005, Canon released the Canon 24-105 mm. fully named Canon 24-105 mm 4.0 L IS. This lens was often sold in combination with the 5D. Today, this lens often comes with the 5D MK2. Said irreverently, it is a kit lens designed for full frame cameras from Canon. Traditionally, a set of lenses of 28 mm, 50 mm and 105 mm was seen as a set with which you can photograph nearly everything. With regard to that set, this 24-105 has a wider zoom range and can therefore be seen as an ideal walk around lens. The full aperture, however, is far less than that of the primes. This is partly compensated by the built-in image stabilization. The zoom range of the Canon 24-105 mm nicely fits the range of the Canon 16-35 mm II and even nicer the Sigma 12-24 mm and the Tokina 16-28 mm.
The lens is made of a high quality type of plastic and the fitting is of metal. With a special O-ring and seals, this lens is sealed against dust and water. The focus ring and the zoom ring run smoothly and without play. The filter remains at the same position when focusing and the lens does not become bigger when focusing. When rotating the zoom ring the length of the lens does change. The lens is delivered including a petal-type lens hood.
The autofocus is of the USM type. Focusing is very rapid with a Canon 5D MK2, from 15 meters to 1.5 meter in just over 0.2 seconds at a focal length of 105 mm. Focusing is virtually silent. Even in low light, the camera does not hunt.
Image stabilization
The image stabilization only has one position; a position to draw along a moving object is not available. Canon claims a gain of three stops; I myself reach about 2.5 stops at a focal length of 105 mm. That is less than the effectiveness of the image stabilization of the Canon 100 mm IS Macro. The Canon 24-105 mm is not a fast lens and due to the image stabilization, the applicability of this lens is greatly increased.
Vignetting
The vignetting in stops is remarkably low even at full aperture. In practice, it will not be necessary to take it into account.
vignetting, @24 mm/4.0 
distortion, @24 mm
distortion, @50 mm
distortion, @105 mm
Distortion
The distortion, expressed as a percentage, is very large at a focal length of 24 mm. At a focal length of 50 mm and 105 mm, the distortion is much lower. Distortion can be corrected with software, including the own RAW converter of Canon, DPP.
Resolution
The resolution, expressed in lines/sensor height is already very high in the center at 24 mm at full aperture. The corners stay well behind. At 50 mm also, the center sharpnes is good at f/4.0 and the conerrs at f/5.6. At 105 mm, the top is reached at f/5.6. This top is lower than at 24 and 50 mm. The Canon 100 mm IS Macro has a significantly higher resolution.
Chromatic aberration
Chromatic aberration is a bit high at 24 mm, this lens error can be corrected by software.
Bokeh
At f/4.0 and at f/8.0, you see that the cover of the blurred circular planes is not smooth. The circles in it create a very unsettled image. The bokeh is less attractive. The Canon 70-200 mm 2.8 II, the Canon 100 mm IS Macro and the Tokina 100 mm Macro have a much nicer bokeh.
@f/8.0
Conclusion Canon 24-105 mm 4.0 L IS review
Advantages
- Low vignetting
- Fast AF
- Handy zoom range
- Seal against dust and water
Disadvantages
- Strong distortion at 24 mm
- A bit too high chromatic aberration at 24 mm
- Hefty purchase price in relation to moderate resolution in the corners at 24 and 105 mm
The Canon 24-104 mm/4.0 L IS is the standard zoom lens for the Canon full frame cameras. The quality, in terms of resolution and color aberrations, is just very average and the bokeh is not very nice. However, the vignetting is remarkably low. Although the finishing is of a high level, the asking price is on the high side.