ERF files are generated by the Epson R-D1 and R-D1s digital rangefinder cameras.
MIME Type
image/x-epson-erf
Organisation
Epson ERF files are TIFF/EP files. CFA data is in the primary subIFD from IFD0. Thumbnail is 8RGB in IFD0. Exif is attached to the ExifIFD of IFD0.
Compression
Apparently the files are "compressed", bit packed. The Compression value in the CFA subIFD is set to 32769.