3 fluorite-like low dispersion, 4 special low dispersion, 2 aspherical
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You are compromising size and weight to get a more reasonable price compared to the Sony 24mm f/1.4 GM lens. Optically you are compromising edge performance to get great center performance. I also noted a few focus glitches here and there along with a centering issue. This lens remains a strong value for those looking for this focal length to use at [...] events, but neither is it a home run as a multipurpose lens or dedicate landscape option.