<https://blog.sigmaphoto.com/2017/sigma-100-400mm-vs-150-600mm/400mm-macro-1500/#primaryimage>
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"The 100-400mm F5-6.3 DG OS HSM | C has a 1:3.8 magnification ratio at 400mm and a close-focus distance of 5.25 feet, which is great for close-up photography, and offers a slight edge in filling the frame compared to the 150-600mm,"
<https://blog.sigmaphoto.com/2017/sigma-100-400mm-vs-150-600mm/400mm-macro-1500/>