You can shoot anything at all. There is no merit to criticisms of the use as a portrait painter. 100-105 mm at the long end is suitable for a portrait. If you utilize one lens to replace a set of two lenses, such as 24-70 and 70-200, you will gain a lot of weight. The 24-70 and 70-200 Canon lenses are all top-notch, and they work well at both apertures of 2.8 and 4 and with and without a stub (70-200 of course). But, it is a bit hefty to carry around two lenses when you don't need to. The two together might not be sufficient. Moreover, a photo walk from 24-105 is preferable.
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