04-19-2013, 08:51 PM
Brightcolours, a f/2.8 is slower than f/1.8 no matter which sensor size.
That was the reason I wrote "you can't just multiply the aperture by the crop factor" - only if it comes to DOF, but not to a gain of 1.5 f-stops faster shutter speeds, not to a gain of a relatively narrow DOF in wide-angle (for APS-C). To compare that shutter speed, it has to be a 28-55/1.8 for FF! And that sounds much less cheap than a 28-55/2.8 - each manufacturer can do that.
I admit, 1.5 f-stops are easily done by contemporary VR/OS devices, one can handhold up to 4 f-stops - but one doesn't get short shutter speeds by VR//OS.
It looks long and thin in the pictures, but given the filter size 72mm, it's a huge piece of gear.
That was the reason I wrote "you can't just multiply the aperture by the crop factor" - only if it comes to DOF, but not to a gain of 1.5 f-stops faster shutter speeds, not to a gain of a relatively narrow DOF in wide-angle (for APS-C). To compare that shutter speed, it has to be a 28-55/1.8 for FF! And that sounds much less cheap than a 28-55/2.8 - each manufacturer can do that.
I admit, 1.5 f-stops are easily done by contemporary VR/OS devices, one can handhold up to 4 f-stops - but one doesn't get short shutter speeds by VR//OS.
It looks long and thin in the pictures, but given the filter size 72mm, it's a huge piece of gear.