IF improves optical performance by minimizing illumination loss at the corners of the image field, and helps to suppress other aberrations

IF provides practical benefits to photographers including a non-rotating front filter ring that facilitates the positioning of polarizing and graduated filters, and more predictable handling because the lens length does not change during focusing. Also, TAMRON's IF system provides a much closer MOD throughout its entire focusing range. In addition, IF improves optical performance by minimizing illumination loss at the corners of the image field (vignetting), and helps to suppress other aberrations that become more troublesome at different focusing positions.