Canon 40mm portrait shooting.

40mm has two advantages over 50mm: first, 40mm has a wider angle of view, and portraits can be closer to objects. To some extent, indoor shooting is a good thing; The second is that the lens is short and easy to carry. But 40mm has two weaknesses: first, the aperture is small, and second, there is no anti-shake. This leads to the need for higher iso in indoor environment with a little insufficient light, which affects the image quality (of course, a studio or a flash can solve this problem well). In fact, this is not a lens specially designed for portraits, but a follow-up lens designed for the convenience of travel, so buying a special portrait will be a bit wasteful. Of course, it is cost-effective to use a small spittoon when taking portraits. If the budget is enough, Sima's 50/ 1.4 or 30/ 1.4 is even better. Of course, it also depends on your other needs. Welcome questions.