Quote Originally Posted by Fast Glass


Hi Rich


The aperture stays open during auto focus, so you don't have to worry about stopping down and slowing the AF.


Cheers,


John.
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Yes John, you're right thanks for catching that.


I should have said a wider faster aperture lens and not opening up the aperture on the current lens.


While we're on that topic.., I have a question about variable aperture lenses that I'm not familar with, since I mainlyuse fast/fixed aperture lenses.


This question is open to anybody.


If you are using a variable aperture lens, does the lens open to the widest aperture that the lens offers or the widest aperture at the current actively used focal length, letsuse the 100-400mm f/4.5-5.6L as the example.


In other words, if I'm at 400mm with that lens, will itopen to f/4.5 for AF or f/5.6?


Thanks,


Rich