If shooting at f/22, is a fast 1.8 lens still considered fast?

Started Apr 17, 2011 | Discussions thread
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SteveL54 Senior Member • Posts: 2,669
Re: tell me Steve

edwardaneal wrote:

So tell me - why does the test I posted above show that AF is more accurate between F/2.8 and F/4 and why does Canon specifically state the following

"The final advantage concerns the focusing. More light can be gathered by these lenses because of the larger maximum aperture making it easier for the autofocus sensors within the camera to find contrast even in low light or low contrast situations. Lenses with smaller maximum apertures may struggle to focus in such low light conditions as they cannot allow enough light into the autofocus sensors."

are they all lying?

The person doing the test doesn't understand the fundamentals of PDAF. Explain the f/1.4 test results. He is assumming a certain cause and effect.

The Canon marketing source you quote is refering to the f/2.8 advantage designed into their AF system.

Steve

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