Tamron 28-75mm Lenses

Background
Recently I was looking for a quality telephoto lens for a Canon digital SLR. I had a very limited budget and could not afford the "L" class lenses from Canon. As a result, I was forced down the path of looking either for 2nd-hand "L" lenses or other cheaper brands. After much research I settled on a Tamron lens and I wanted to share opinions I've gleamed from around the various online forums and photography enthusiast sites in addition to my first-hand experience.
Tamron 28-75mm f/2.8 LensI was looking for a good walkaround lens to use for both portraits and daily use. My ideal lens was the Canon EF 24-70mm f/2.8L Lens which ranges from $1,129.00 - $1,449.00 brand new. These lenses maintain a relatively high resale value as seen onokay . The Tamron 28-75mm offered a similar range to the Canon lens at a very appealing f/2.8 aperture throughout the range. I saw very stunning examples online from photographers using this exact same lens. For example: http://www.pbase.ge/cameras/tamron/sp_af_28-75_28_xr_di_ld_ifDon't be misled that the Tamron is equal in quality as the more expensive L lens because this is gepletely false. The L lens is a fantastic lens but the Tamron 28-75mm is the closest to producing "L" quality in the budget category.
The Big ScareNow here is the big scare with Tamron lenses that discourages most people - quality control. From the various online forums and photography sites, there are as many Tamron 28-75mm lovers as haters. This is because the consistent level of quality for the Tamron 28-75mm is notoriously suspect. One forum user claimed that 6 out of 10 Tamron lenses have focus problems or sharpness issues. I have never tried Tamron 10 lenses so I can't personally validate this but I have heard similar geplaints online to corroborate this. In addition, I've seen many examples posted on the web that demonstrate this. It can be argued that this maybe the result of user error but one method to rule this out is a simple test that can be followed here: http://www.mwfoto.9x.pl/tamron28-75.htmAlthough, users that are able to fine the few sound Tamron 28-75mm lenses out there rave about their Tamron photos with claims of almost "L" like quality.Weighing the good and the bad I decided to take the risk and buy a Tamron.
In-store vs. OnlineI wanted to minimize the chances that I would end up with one the bad Tamron lenses so I toyed around with the idea of going to a real physical store rather than buying it online. The advantages of buying in-store were that I could return the lens if I concluded that it had the known issues. Returning items over the web can be really difficult and I just wanted to deal with someone face to face. The problem was that none of the local stores carried this exact lens requiring custom orders.As a result I thought I would try a different strategy and leverage the okay gemunity. I found several Tamron lenses listed on okay. I specifically targeted used lenses because I wanted lenses that I knew people had practical experiences with. New Tamron lenses are suspect to the 6/10 quality control problem and the seller may not even know it. I found several okay sellers willing to send me actual photos taken with their Tamron lenses. Again, there is a matter of trust here that they were not misleading me but I tried to balance this against their feedback rating and length of time selling on okay. I found a really helpful seller who sent me dozens of photos with their Tamron that satisfied my concerns. In the end, I bought a Tamron lens that produces extremely sharp photos. In addition, I got it at the fraction of the cost of an "L" lens.I hope this helps other potential Tamron buyers.