I've got a 24-70 f/2.8L (original version) and I've been thinking about a 'cross-grade' to a 24-105 f/4L. With a crop I used to use it a lot for portraits but since moving to FF (now own a 5D3) I normally use a 70-200 for that and 24-70 only gets used at f/4 or above most of the time anyway and often for things where IS would be a benefit. I use a 50mm if I want something faster.
Anyway I know a f/4 lens will technically focus slower in low light than a f/2.8 but just wondered from someone who's used both how low light AF between the two compares? I thought maybe despite f/4 the 24-105 may have a more modern / faster AF drive so maybe not too much of a difference in practice?
Anyway I know a f/4 lens will technically focus slower in low light than a f/2.8 but just wondered from someone who's used both how low light AF between the two compares? I thought maybe despite f/4 the 24-105 may have a more modern / faster AF drive so maybe not too much of a difference in practice?