Originally posted by Winder 1. The Sigma actually beats several primes for speed and sharpness.
2. I do a lot of event work where flash is not allowed, so speed is more important than size.
But with the Sigma so big, there's no longer any advantage to shooting APS-C.
You'd do better enjoying the extra zoom range a 24-70/2.8 gives you on FF.
Originally posted by Winder 3. The tests I have seen show that the 20-40mm is best at 30mm stopped down to F/5.6.
Which tests would those be? (BTW, my experience with the actual lens shows otherwise.)
Even DXO, which reduces reductio ad absurdum to new levels of absurdity,
says that the lens is best at 35mm and f/4.
Originally posted by Winder 4. There are better walk around lenses for the money if you are a casual shooter.
I agree. If you are a casual shooter, just out for record shots, the DA 20-40 would be wasted on you.
Originally posted by Winder The limited zoom range, speed, & cost are not a good combination.
Those features are not the USPs for the DA 20-40.
But they are what make possible the lens's unique combination
of WR, small size, flare resistance,
and rendering in the same league as the best primes.