09-14-2016, 02:28 PM
The 15mm f2 lens is not a DSLR lens which sits a big distance (40+ mm) to the sensor, rather the flange distance is around 17mm.
That makes the lens easier/smaller to design than one for a DSLR, and explains the size, more or less. Wide angle is where mirrorless with smaller flange distances can have the advantage.
Why the 7.5mm f2 lens for MFT is that small? Because it is a 15mm f4 FF equivalent lens with a small aperture, and again it has the advantage of a 17mm or so flange distance rather than 40mm + for DSLR lenses.
The pancakes suffer mostly from design restrictions due to the limited room length wise (can't fit too many elements in there), and possibly less gifted designer in case of the Sony? This 7.5mm lens has a lot more length to play with, and with the small image circle the elements can comparatively less thick too, needing less space.
That makes the lens easier/smaller to design than one for a DSLR, and explains the size, more or less. Wide angle is where mirrorless with smaller flange distances can have the advantage.
Why the 7.5mm f2 lens for MFT is that small? Because it is a 15mm f4 FF equivalent lens with a small aperture, and again it has the advantage of a 17mm or so flange distance rather than 40mm + for DSLR lenses.
The pancakes suffer mostly from design restrictions due to the limited room length wise (can't fit too many elements in there), and possibly less gifted designer in case of the Sony? This 7.5mm lens has a lot more length to play with, and with the small image circle the elements can comparatively less thick too, needing less space.