09-07-2011, 08:11 AM
[quote name='Sammy' timestamp='1315381900' post='11365']
Doesn´t the field curvature issue disappear when the lens is stopped down? I think this was the case for the Tamron 17-50 mm f/2.8 lens, which however is not ultra-wide.
[/quote]
To my knowledge, FC is never 100% avoided by stopping down. But of course increasing DoF reduces the soft corner effect... OTOH, more importantly, a lens designed for UWA shots cannot perform such flatness on the sensor surface by definition. Longer FLs have the advantage here because of the optical design (the one in Merklinger's example was a 90mm).
But concerning the method (if we ignore lens characteristics dependend on the design), I'm still confused by using the "size" of the object as the key factor for the DoF setup. How will I guess the size of the photographed object in foreground (in practical terms)?
Serkan
Doesn´t the field curvature issue disappear when the lens is stopped down? I think this was the case for the Tamron 17-50 mm f/2.8 lens, which however is not ultra-wide.
[/quote]
To my knowledge, FC is never 100% avoided by stopping down. But of course increasing DoF reduces the soft corner effect... OTOH, more importantly, a lens designed for UWA shots cannot perform such flatness on the sensor surface by definition. Longer FLs have the advantage here because of the optical design (the one in Merklinger's example was a 90mm).
But concerning the method (if we ignore lens characteristics dependend on the design), I'm still confused by using the "size" of the object as the key factor for the DoF setup. How will I guess the size of the photographed object in foreground (in practical terms)?
Serkan