hello, here is another noob question I am not professional, not even aspiring to be one, so the use is pure recreational/hobby. I have another really expensive hobby besides photography, so I have to balance my budget. I am discovering that what I like to shoot the most are the people, candids and staged, landscapes and occasional action scenes - dances, motorsport events and such. I have XSi body and 50mm/f1.8 and sigma 18-200 f/3.5-6.3 DC OS as my walk around lens. Recently after going to circus and some other poorly lit places, I discovered the limitations of my lenses and looking to improve my lens setup. I was thinking of selling my 18-200, and my kit lens (18-55 IS) adding couple hundreds to that and hopefully have around 600-700 to play with. I would want to get 2 lenses instead, - one - for a day to day - something like 24-70 and second in 70-300 length. I am not looking for L lenses and such, I just can't justify such an expense for a hobbyist on budget. i was thinking of getting something like Sigma 28-70mm f/2.8 EX DG IF [ame]http://www.amazon.com/Sigma-28-70mm-Aspherical-Canon-Cameras/dp/B00063KO5W/ref=sr_1_1?ie=UTF8&s=photo&qid=1227907175&sr=1-1[/ame] or Sigma 18-50mm f/2.8 EX DC SLD ELD [ame]http://www.amazon.com/Sigma-18-50mm-Aspherical-Digital-Cameras/dp/B000JDJJ82/ref=sr_1_1?ie=UTF8&s=photo&qid=1227907405&sr=1-1[/ame] and something in 100-300 range with OS from Sigma or IS from Canon up to $350-400 maybe Canon EF-S 55-250mm f/4.0-5.6 IS [ame]http://www.amazon.com/Canon-55-250mm-4-0-5-6-Telephoto-Digital/dp/B0011NVMO8/ref=pd_cp_p_1?pf_rd_p=413862901&pf_rd_s=center-41&pf_rd_t=201&pf_rd_i=B0007Y794O&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0DJNP8ZCKJ28HYCNPN0Q[/ame] or Canon EF 70-300mm f/4-5.6 IS USM if I can get a good deal or find it used in good shape [ame]http://www.amazon.com/Canon-70-300mm-4-5-6-Lens-Cameras/dp/B0007Y794O[/ame] I was reading reviews and opinions, but they are all contradicting and confusing, so I decided to ask here: are any of those selections - "stay away from" or the opposite - "very good value for the price"