Currently my equipment consist of EOS 50D, EFS18-200mm f/3.5-5.6, EF50mm f/1.8, EF 100-300 f/4.5-5.6 USM. I mostly use 18-200mm at all times but I'm not entirely satisfied with it, specially in low light situations. I will eventually will upgrade to full frame, but in the meantime I want expand my glass collection. With a budget of $2000, what lens or lenses would you recommend? Thanks
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