Quote Originally Posted by justThorne


My 24mm f/2.8 is certainly extremely accurate at infinity - stunningly so, actually. My 100mm Macro might be less accurate, compared to its specialty. My 50 f/1.4 might definitely be less accurate - I'm not sure but years of experience with (three of) them make me feel infinity is its weak flank (though I'm actually talking about its AF performance, rather than the glass itself).


But I'm confused about "wastes the depth of field behind infinity focus point." Do you mean (to sometimes regret) that "it's all one big flat plane out there"? Yeah, lack of focal differentiation at a distance (from shorter lenses) would sometimes be frustrating, but my point here is to talk about the opposite times in which it wouldn't be.


And my biggest point, as I said, is to wonder why this is all discussed so rarely.




Thanks for the response! I think it is discussed fairly frequently actually, at least I have seen it discussed on various forums.


What i meant by wasting depth of field behind infinity focus point is... when you focus, the place you have focused is the sharpest area of a photo. You have a front DOF and Rear DOF that surrounds that focal plane like an oval inner tube. That tube is longer/shorter depending on aperture. If you focus at "infinity" you have an entire area of rear depth of field that is not used at all, it encompases no subject matter because you already put the focus point at the farthest subject. So up close subject matter (if there is any) is not resolved as well as it could have been. But like I said its only really a negative if you didn't want that "infinity" subject matter to be most focused.


Also what I was referring to is the fact that the manufacturer builds the infinity mark on the lens, but there is often times an ability to focus beyond that mark due to extra leniency provided by the manufacturer.