Those 5 diagonal cross-type autofocus sensors on mark III will work only with f/2.8 and faster lenses. So, if you need extra AF speed, precision and reliability, f/2.8 lenses will still be better than f/4 ones.Dennis Ernst said:With the new 5D mark III and the high ISO speeds it will bring, do you still need or want a fast lens? Will a f/4 work just as well as a f/2.8 with a 5D mark II? Will it change the lens you might buy for it in the future?
Dennis Ernst said:With the new 5D mark III and the high ISO speeds it will bring, do you still need or want a fast lens? Will a f/4 work just as well as a f/2.8 with a 5D mark II? Will it change the lens you might buy for it in the future?
WJM said:Here are some situations when you might need high ISO speeds and a fast lens:
1. Indoor action sports. Now some sportshalls are too dark to shoot decent pictures.
2. Fast moving animals in the woods while the dusk sets in.
With the newer cameras with higher ISO speeds it is posible to shoot in these situations (while it was not possible before) but you still need fast lens (else the gain in shutter speed is gone).
With the exception of the 50mm f/1.4 prime, the actual supply of fast lenses seems better than in the film era. And if you go back to the 1970s and earlier the zoom lenses tended to be slow by today's standards.koolman said:True, that as ridiculously high ISO's are usable in the advanced DSLR world, the necessity of a fast lens for decent images in low light situations - as we used to have in the film days and older digital days - is less.
heheapa said:Professionals goes to fast lens are usually for the DOF and the Faster AF at low light, not just purely for faster shutter speed.