Photo taken on a 5D Mark II with Sigma 50mm f/1.4.
One difficult choice for Canon photographers is between the 24-70mm f/2.8L and the 24-105mm f/4L IS. It's a choice because as, both lenses cover pretty much the same medium-range zoom length, instinctively it seems sensible to own one or the other and not both. However, each lens offers a slightly different but seemingly balancing set of advantages and disadvantages so it's difficult to know which set of characteristics to go for and which to try to manage without.
This dilemma is a regular topic on photography forums. In some discussions, more people prefer the 24-70; in others, the 24-105 comes out on top. Some people have switched from one lens to the other and back again. Some professionals recommend the 24-70; others the 24-105. It seems that there is equal preference for each lens.
I am a photography enthusiast - not a professional - so I didn't think the differences between these two lenses would be something I would need to think about anytime soon. But then I booked a three week holiday to Japan and decided I wanted to take the best gear I could with me, especially as I could sell my 24-105 and replace it with a 24-70 for relatively little net cost. So, a couple of days ago I bought a 24-70 anticipating that I would either sell the 24-105 or return the 24-70.
As I have spent so much time trawling through photography forums trying to work out which of these lenses is the one to keep, I thought I would summarise my findings here with a view to helping others now or in future facing the same choice. I have added a few preliminary thoughts on the 24-70 and will flesh out my findings once I have used it more.
(1) Focal length
The 24-105 covers 35mm extra on the telephoto end than the 24-70. Numerically, the 24-105 covers 76% more range than the 24-70; the 24-70 covers 56% of the range of the 24-105.
A number of people have commented that the additional 35mm of the 24-105 can come in very useful, particular when traveling. However, some of those say that the lens is weaker in the 70-105 range. Those who also own a 70-200 lens appear to prefer that lens above 70mm.
On my 24-105, I shot various scenes at 70mm and 105mm to get a feel for what I would miss if I exchanged the 24-105 for a 24-70. I realise that I could manage with the 70mm limit because (i) as the 5D Mark II produces very high resolution files I would not hesitate to crop photos at 70mm slightly and (ii) I would always prefer to use my 70-200mm f/2.8 IS when reaching beyond 70mm.
Having experimented with the 24-70 this evening, it seems that its quoted zoom range does not correspond with 24-70mm on the 24-105. The 24-105 seems slightly wider at all lengths.
The aperture of the 24-70 is f/2.8; the 24-105 is f/4. The difference between f/2.8 and f/4 is one stop. This means that the 24-70 collects twice as much light. In the real world, with the 24-70 set to f/2.8 and the 24-105 set to f/4, the 24-105 requires twice the shutter length to take the same photo. In a poorly lit scene with moving subjects, those moving objects would be twice as blurred on the 24-105 as the 24-70. That can make the difference between keeping and deleting a photo.
The other differences are depth of field and background blur (bokeh). f/2.8 is shallower than f/4 which means that out of focus subjects become more out of focus on the 24-70 than the 24-105. Although one stop extra is relatively small, it can make the difference between the background being pleasant or distracting - and therefore whether a photo is to keep or for the bin.
Some say that with challenging backgrounds the 24-105 is can produce an uneven bokeh or give unpleasant artifcats and the 24-70 more often gives a smoother result. It's amazing to think that the precise shape of the aperture hole can make so much difference, but these comments are backed up with fairly good evidence.
Others have commented that they use a 24-105 in conjunction with fast prime lenses where significant background blur is required and that a fast prime lens would produce much more blur than a 24-70. These points are compelling, but as my eye naturally picks up on subjects which contrast with the background, I have found that I have used my 24-105 very rarely because f/4 has been inadequate in so many situations. And yet when I have used my 50mm f/1.4, I have not infrequently selected an aperture of f/2 to f/2.8. This indicated to me that I could benefit from the 24-70's f/2.8 aperture greatly.
(3) Image Stablizer (IS)
The 24-105 has a three stop IS. The 24-70 has no IS. In certain poorly lit scenes with no moving subjects, it would be possible to take a sharp photo hand-held on a 24-105 but not on a 24-70. If that same poorly lit scene had moving subjects, as IS compensates only camera movement, those subjects would be blurred on both lenses.
The 24-105 is therefore favoured by those who primarily shoot static subjects such as buildings and interiors. The 24-70 seems to be preferred where humans (particularly children) are the subject because the 24-70 set at f/2.8 can take the same photo but using half the shutter duration as the 24-105 set at f/4.
Many people comment that IS is invaluable; many others say it is rarely beneficial and is only of real benefit on longer zoom lengths. To some extent this depends on how steady your hand is. I can understand why at the wider end in particular IS may be of limited benefit: a small camera shake will result in a minute difference to the overall scene and so produce little or no blur.
Having used the 24-70 for just a day, while it has certainly proven necessary to hold it more steadily than the 24-105, I have been able to obtain sharp images on the 24-70 hand-held in relatively low lighting.
The 24-105 weighs 670g; the 24-70 weighs 950g. Many people seem to prefer the 24-105 for traveling because it is lighter. For me, if I am going somewhere that I cannot visit often, I would want to use my best gear and not worry about a little extra weight; the additional tiredness at the end of the trip would hopefully be outweighed by the quality of the results. Given the weight of my bag, camera, 70-200mm f/2.8L IS and any other lenses and accessories I might take, 320g seems to be an immaterial difference.
The lens hood for the 24-105 mounts on the moving element of the zoom mechanism and is shorter in length. The hood for the 24-70 mounts on the body of the lens and does not move with the zoom mechanism; it is longer than that on the 24-105 because it needs to be effective when the moving element is at its furthest.
Forum users have commented that, with its hood attached, the 24-70 may attract more attention and may be mistaken for a more longer, more intrusive zoom lens.
Some have commented that the hood of the 24-70 is more practical - at 70mm, the hood extends about 8cm from the front element; the hood on the 24-105 at all lengths extends up to 4cm only. The longer the shade, the more unwelcome light sources are blocked and the less likely lens flair is to occur.
(6) Overall picture quality
Some comment that the images from the 24-70 are simply 'better'. Others say the 24-105 produces 'better' results. It could be that those who prefer the 24-70 do so simply because of the additional or smoother bokeh. Those who prefer the 24-105 might find their images more consistently sharp because of the IS. I have not used the 24-70 enough to have a preference yet.
The 24-105 is known to suffer a very noticeable amount of barrel distortion at the wide end. Although this can be corrected in software, the result is that around two or three mm are lost.
I spent a couple of hours this evening examining sharpness from the two lenses. At the wide and telephoto end, photos are sharper in the centre on my 24-70 than my 24-105 at f/4, although both are acceptably sharp. However, the 24-105 is much sharper at the edges and corners. In fact, I hadn't realised until this evening just how impressive my copy of the 24-105 is in terms of overall sharpness: even wide open at f/4, the edges and corners remain acceptably sharp.
Another finding was that both my 24-70 and 24-105 are sharper than my Sigma 50mm f/1.4 - irrespective of aperture. I would have expected the Sigma to perform much better at say f/4 but it remains soft. I'll only use my Sigma 50mm f/1.4 for night and extreme bokeh photography from now on.
I noticed when comparing the lenses indoors that my 24-70 produces slightly more contrast than my 24-105. I'm yet to do a comparison outdoors to determine whether this makes for 'better' photos.
(7) Wrap up
Rumours of a 24-70mm f/2.8 IS lens have been doing the rounds for years. The 24-70 has been available since 2002 and some say a refresh is overdue. A cynic might say that Canon won't produce such a lens because more money can be made by selling the 24-70 non-IS and 24-105 IS both of which have a place in some photographers' collections. As Canon have made the 17-55 f/2.8 IS for crop cameras and such zoom range is almost identical to 24-70 on a full frame camera, it seems inevitable that a 24-70 f/2.8 IS will emerge one day.
So, which one will I keep and which will I sell? At the moment, I just don't know! I may even keep both all year as I can't see me being able to part with either anytime soon.