inane prattle

Started Apr 8, 2013 | Discussions thread
Paul De Bra
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That statement is wrong for a different reason...
In reply to James Pilcher, Apr 8, 2013

It is true that sensors have become better and IBIS is very good as well. But there is another reason for still wanting faster lenses:

- Typically a lens is at its best when stopped down at least 1 stop but in most cases 2 stops.

- With the smaller m43 sensor (relative to 35mm) diffraction sets in earlier. The optimal f-stop for m43 seems to be f/4, with f/5.6 still quite usable but f/8 starting to show diffraction.

These two factors combined mean that unless a lens is already at its best wide open you need at least an f/2.8 lens (1 stop down means f/4 and 2 stops down means f/5.6 so that just does it) and that f/2 is actually a safer bet (with 2 stops down reaching the optimal f/4 stop).

So the only really valid argument that says we don't need faster lenses (except for shallow DoF) would say that we don't need lenses faster than f/2.

If you would translate this story to APS-C it would say that f/4 lenses are acceptable and f/2.8 is better, and for 35mm f/5.6 is acceptable and f/4 is better.

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