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500mm vs 600mm?

Started Nov 13, 2017 | Questions thread
WilbaW
WilbaW Forum Pro • Posts: 11,643
Re: 500mm vs 600mm?

Tannin wrote:

And there is nothing, repeat nothing, so useful as having f/4 at your disposal. Be it for depth of field control, for faster shutter speeds, for faster, better auto-focus...

It's a common misconception that an f/4 lens will PD AF better than an all-other-things-being-equal f/5.6 lens. There's no advantage since they both pass the same intensity of light to the AF sensors. With PD AF it's a can the sensors see through the window thing, rather than a how bright is the room thing.

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