Hi. Let me start off by saying i wish i had thousands to spend on a hobby but i don't so have to do things on a tight budget. I enjoy taking photos of landscapes and motorsport. I'm getting back into DSLR photography after a few years away. My last camera was a canon 450d which i bought with a kit lens only but then bought a Tamron zoom lens, i can't remember the spec's exactly but it was something like 28-300mm. I like the idea of having a lens that covers a large range although i do realise image quality suffers. I was never very impressed with the quality of the pictures i took with the Tamron, just wasn't as sharp as the kit lens. So, I'm now looking at replacing my kit lens with an 18-200mm to get similar quality to the kit lens but with a bit more range. Are Sigma better than Tamron or not? If you think i will be disappointed what would you suggest i look at? Thanks.