The RF 24-105mm f4 L IS lens was one of the first RF mount lenses to be released and it remains one of the best and most versatile.
If I could have only one lens for my EOS R camera this would be it.
Although the RF lens catalogue is relatively new Canon already offers four standard focal length range zooms.
At the top we have the exotic RF28-70mm f2.L Presumably Canon released this to demonstrate that they can do it. The lens although big, heavy and very expensive ($4400) is not stabilised. Owners will no doubt be pleased when the EOS R5 with IBIS finally arrives.
Next down the price scale we have the standard professional workhorse RF 24-70 f2.8 L with IS at $3900.
Third on the list is the smaller, lighter and less expensive ($1500) subject of this user report, the RF 24-105mm f4 L IS with 50% greater zoom range than the 24-70mm.
Last comes the RF 24-105 f4-7.1 IS consumer utility zoom. I have one of these on order but it is held up somewhere in the Covid19 lock down. This one is another level smaller, lighter and less expensive ($700) than the f4.
I suspect that for many enthusiast amateurs and professionals the 24-105 f4 will find favour as it offers a very nice balance between price, size and performance.
Mechanics
An EOS R with the 24-105 f4 mounted weighs 1350 grams which is enough mass to steady the camera when hand held but light enough to carry all day if required.
There are three rings on the barrel. Zoom is rearmost with a little step in the surface making it easy to locate by feel. The zoom action is smooth.
Next comes focus and at the front is a clicky function ring.
There are slider switches for AF/MF and Stabiliser on the left side of the barrel.
There is a rubber weather seal O-ring around the mount.
Filter size is 77mm.
A reversible petal type lens hood and soft carry pouch are supplied.
There is plenty of space for fingers between the handle and the lens barrel.
The stabiliser and focus motors are very quiet. The stabiliser is very effective allowing very slow hand held shutter speeds.
Autofocus is very fast and accurate. The lens will focus accurately in very dim light without the AF assist beam.
Optics
Sharpness is very consistent across the whole focal length range being excellent in a large central area of the frame and slightly less sharp in the corners at f4. The corners become very sharp when the lens aperture is reduced to f5.6-f8.
The lens will deliver a nice sharp result at any focal length and aperture with the main subject anywhere in the frame.
There are modest levels of distortion and corner shading easily corrected with a profile in Adobe Camera Raw or similar.
Mild color fringing can be seen with some high contrast subject elements, easily corrected.
Flare can be induced if the sun is deliberately located near the edge of the image frame.
A small change in camera angle will often avoid this.
Recommendation
Here is a lens which does everything that matters right and gets nothing significant wrong.
The focal length range is very versatile.
The maximum aperture of f4 admits plenty of light and enables good depth of field control.
Buy it.
Use it.
Happiness will flow.
Good pictures too.