Sigma press release:
Sigma Corporation of America to Release Two MTF Charts for Measurement of Lenses
Company releases the data of Geometric and Diffraction MTF charts for Global Vision Lenses
RONKONKOMA, N.Y., — February 3, 2014 – Sigma Corporation of America, a leading researcher, developer, manufacturer and service provider of some of the world’s most impressive lines of lenses, cameras and flashes, today announced that the company will now release a Geometrical MTF (Modulation Transfer Function) chart in addition to a Diffraction MTF chart when measuring the performance of all new Global Vision lenses.
MTF charts are important because they help photographers better understand the optical quality of lenses. Sigma has traditionally released Diffraction MTF data because it takes the diffraction quality of light into consideration, which can dramatically affect the data outcome. Diffracted light exists at every aperture, giving photographers a more accurate measurement of how the lens will perform in real life. Although Geometric MTF data is easier to measure and calculate since it does not consider the diffraction quality of light, it tends to show higher values in the graph and less defined results.
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