Given that Panasonic 25mm carries the Leica name it is reasonable to think it will be more expensive than its peers. It is also reasonable to expect that it should be something a bit special, but is it?...
-Quick AF system
-Responsive MF control
-Excellent MTF figures
Given that Panasonic DG Summilux 25mm f/1.4 ASPH carries the Leica name it is reasonable to expect that it should be something a bit special. It is also reasonable to think it will be more expensive than its peers. As it happens, both notions are correct and the appeal of this lens depends heavily on the extent to which its special features are considered sufficiently desirable to justify its additional cost.
Putting the Leica name to one side, the outstanding feature of this lens is its ultra-fast maximum aperture. On a reflex camera ultra-fast apertures provide brighter viewfinder images but that advantage is much less important when the camera uses an electronic viewfinder. The other two advantages, however, that remain: there is still the ability to use narrow depths-of-field to isolate a sharp subject against an out-of-focus background; and the option to use lower sensitivity settings in combination with shorter exposure times. These benefits, like the classic Leica moniker, are more likely to appeal to creative photographers than to people who simply want to point-and-shoot.
But an ultra-fast maximum aperture is a hollow offering if the MTF results do not support its use by quality-conscious image makers. Fortunately, DG Summilux has MTF figures that are comfortably above the critical 0.25 cycles-per-pixel level from the start and they only touch that threshold at the very end. One reason for this is that the aperture range extends only to f/16 when it is clear that to have included an f/22 setting would have meant accepting an MTF figure well below the critical level.
A nice touch that Panasonic offers through the host Lumix GF3’s menus is the ability to have an enlarged area (for manual focusing) set within the overall frame, so that most of the scene can still be viewed while the centre (or any other chosen region) is magnified to confirm optimum sharpness. This is not really a feature of the lens but it is indicative of the extent to which bodies and lenses are now inter-dependent in more ways than was previously the case.
Similarly, Panasonic stresses that the Nano Surface Coating used on this lens is a Panasonic technology that ensures anti-reflection effectiveness right across the visible spectrum. In fact the range stated (380-780nm) extends beyond the visible spectrum and well into infrared wavelengths that might also degrade image quality if left unchecked.