The concept of "mirrorless" has become popular, and there are more mirrorless products available. Prior to this, we had the third generation Olympus E-P and Panasonic GF series, followed by the newly emerging Pentax Q. Not to mention the continuously细分ing Sony NEX series, and the oddball Ricoh GXR. Their sensor sizes vary, and their prices differ by thousands. What exactly are the differences? Which one is the most suitable for you?