looking for a good low light zoom fast lens for my canon 70d. budget up to £400 for a second hand. have a 30mm 1.4 and a tamron 17-50 2.8. might get rid of the tamron depending on what i get. possibly use the new lens for video as well but mostly for kickboxing shots or should i save my money and keep the 17-50?.any help much appreciated.


