L-rumors got very wild rumors about a possible new 60MP sensor that might be used on the FP-L:
Source 1:
SIGMA fp L use a special pixel type effective 60.75 megapixels sensor named IMX513BQR from sony-semiconductor to replace the unstable Foveon X3 sensor. in 30 megapixels output mode, pixel can be full sampled, which makes it the same image quality as the Foveon X3. in 120 megapixels mode, fp L output the maximum resolution in the world of full frame single shooting.
Source 2:
The newly CMOS sensor of sigma fp L has a CFA like the fujifilm’s Super CCD. Sigma get a customized full frame 61 megapixels no-LPF BSI sensor with zig-zag manner pixels and 45° rotated bayer color filter array, which pixel design based on sony-semi’s most popular 3.76um Exmor R series. This special pixel array was name as “Q67” or “ClearVid” in sony’s speech, was used in F65RS cine camera.
This 61 megapixels zig-zag pixel sensor can output 30 megapixels green channel image without any interpolation and color the picture like the Foveon X3 Quattro. So it can be the flat version of Foveon X3, but save the high ISO.
In additionally, this customized sensor use the same color filter as the PhaseONE IQ3 100MP Trichromatic. It has the best color reproduction even better than the old Foveon X3.