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

Started Apr 17, 2011 | Discussions thread
noirdesir Forum Pro • Posts: 13,561
Re: so here is nikons final answer

DRode wrote:

Thanks for getting this straight from Nikon. I was always told that faster glass benefits the Nijkon AF system. In fact, my own experience would seem to support this. But recently I've read a number of comments that this was not the case. One poster even referred to some kind of "baffles" that would damp the light down to f/5.6 even if the lens were capable of much wider apertures.

These 'baffles' are real (see the green parts below to understand what they do), even Edward has accepted that. He is just of the opinion that Nikon must use both f/2.8 and f/5.6 PD-AF sensors because Canon uses them (and Nikon would be stupid not to use them as well, probably similarly to Nikon using FF sensors prior to 2007 because Canon was using them). And that Nikon has designed its AF system such that a simple test for the existence of f/2.8 AF sensors (which is done by blocking the light to the f/5.6 sensors as indicated in red in the drawing, if there are f/2.8 sensors, the AF should continue working, if there are none, it should not work, which is what is observed) would fail, so the existence of f/2.8 AF sensors in Nikon cameras could be kept secret.

The e-mail from Nikon shows no sign that the person is actually understanding how PD-AF works, otherwise he would be more specific and say that Nikon uses both f/2.8 and f/5.6 AF sensors.

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