mayerk wrote in post #7241829
-I'm guessing IQ will probably be the same with both, but if someone can confirm or deny this,I'd appreciate it.
...
-So what do you guys think?
I don't own the 24-70/2.8L. I do own the 24-105/4L. But I think I can be objective.
The 24-70/2.8 might perform that little bit better, though they trade places at various focal length. The f/4 lens is perhaps a bit better at 24, and the f/2.8 lens is maybe a bit better at 70.
The IS more than makes up for the lack of that additional stop of speed, if the question is an adequate shutter speed for hand-holding. Of course, it won't help if the subject is moving, and it won't give you the same thin depth of field for achieving selective focus.
But the f/4 lens gives you more reach, and it puts something over a hundred bucks back into your pocket.
So, if you want extreme selective focus for portraiture, then the 24-70 will get you closer but still not nearly as good as you'd get with even the Nifty Fifty. You can make up for that by using the 105 end of the f/4 lens, which will require a bit longer working distance and therefore less depth of field compared to the 70.
And if your subject is just fast enough so that f/4 is too slow but f/2.8 is fast enough, then you know what to do. But is that one stop going to solve many problems in the real world? Probably not. If you need that sort of speed in a short telephoto, get the 85/1.8.
But if you just need hand-holding stability in dark conditions, the IS in the 24-105 will give you more headroom than the extra stop in the 24-70.
You can't really go wrong with either lens, but the difference is in how you intend to use them.
Rick "who figures it's his turn to answer this oft-seen question" Denney