Lens question Canon 85mm 1.8 vs Sigma 70-200 2.8
Hello, new member here and I have a question for those of you that have used the above lenses. I already own the kit lenses (18-55 and 55-250, both IS), a Canon 50mm 1.8, and a Tamron 28-75 2.8. My question is for my next lens, do you suggest the Canon 85mm 1.8 or the Sigma 70-200 2.8? I have a Canon T1i and shoot on the side (not my main business obviously). When I do have jobs, they are typically family shots or birthdays (which the 50mm and Tamron 28-75 have served well for). I am a second shooter for a couple weddings coming up and wanted your opinions on if the lighter, faster, and cheaper Canon 85mm 1.8 might be a better choice than the Sigma 70-200 2.8. I do have an external flash so 2.8 isn't hindering the wedding reception, but also enjoy shooting natural light portraits.
I just did a test shot in my living room with no flash and found with my 50mm I can shoot at 1/40 at 1.8 and only 1/10-1/15 at 2.8, which is way too slow for my needs.. I have always liked the idea of the 70-200 2.8, but now I'm starting to think the 85mm might be a better choice for me as my next lens, and maybe save up for the 70-200 2.8 after that. I'm thinking the faster indoor (ie reception hall) and faster auto focus motor might be the winning attributes right now. Any comments and feedback are appreciated, and no, the Canon 70-200 2.8 IS is not in my budget =/