Extending the effective focal length of the Sigma dp3 Quattro's lens by 1.2x, the Conversion Lens FT-1201 brings the 35mm equivalent focal length to 90mm without affecting the f/2.8 maximum aperture setting. Four glass elements in three groups help to maintain image quality and a rear gelatin drop-in filter holder is also incorporated into the seamless design.1.2x conversion lens effectively extends the dp3's 50mm focal length to 60mm, which is equivalent to 90mm in the 35mm format.Four elements in three groups design helps to maintain the original image quality.With the conversion lens in place, the minimum focusing distance is lengthened to 11.6" and the maximum magnification ratio is 1:3.6