Then, go back and forth between the three main competitors had launched. If you are looking for this, probably 2.8 Tamron 17-50 venture with the more expensive Canon 18-55 2.8, but much loved for many years the weight of the material. I finally broke down and went to the store to wrap your hands around the three, a shooting of a video comparison of some focus ring / zoom and the company / operating system and test Futz not completed before the professional quality of 'image, but you can easily find a comment online. In many parts of the Tamron and Sigma do not have the same low distortion Bokeh. Tamron also clear that some are 2.8. 2.8 sigma when I point the camera in a window or light source is easily visible in the corners of some circular distortions do not have to. Basically, I draw the image quality between the lenses was determined. Canon is a test a bit 'better, but I really want in the first 2.8-room, I WAS getting all kinds of sense to see through the lens to find. I was in town for pro shop and rental customers and other adverse conditions, experts and if you have experienced a sense of my question, said nerago. So in the end all in terms of quality difference between 3 optical lenses is very little decided.
The price for the left, the handful of construction and vibration control.
Price: Canon is about $ 1,080, Tamron rebates, with about $ 550, $ 640 for Sigma is that you (including taxes), depending on the point of sale
Channel: Canon has the best overall treatment. I am concerned mainly with high-end video recording, so the Focus range is particularly important as focusing ring (soft) because the handle. The front is the Canon wins hands down. Since hitting the beach, keep the focus ring if you know you up, not you. Both Tamron and Sigma are hard to stop. Canon also, so if you can follow the focus and follow focus should be equipped to provide the flexibility, this is the life much easier. Sigma Tamron, but only 20% had a longer range than the latter. Tamron ring was taken a bit 'nervous. If I apply the pressure outside of the ring does not stick. Sigma was a soft, slightly damp cloth. However, it is super close. It 's the only complaint about this. Your habit of judging the most significant attention from home, the number and skills of the killer can pull this off. extraordinary sensation of the ring, not challenging but not impossible. That will be easier to attack than Tamron Sigma, discovered thanks to the quality of the Rings. For video applications, the problem of auto-focus has nothing to do. Are you a career, super quiet, but you probably have this type 9 manual anyway. The extent of development of these (what I mean around the ring road) and Sigma limited use because it is the video, are still on the Canon Paying $ 475 more I'm thinking of leaving. This is what I would buy a Canon Sigma is the only reason.
Build: As I said the other ratings, Sigma is solid. It feels good. The fact that Canon zoom ring to beat your brain. Lighter than the Canon, Tamron, but made with more robust materials. In terms of construction, I think Sigma has been assigned.
Vibration Control: After all my tests, it is difficult for me at the front was measured. With Canon, a company are clear. It 'also evident with Tamron. For some reason, despite the obvious difference that I will not flick. If the image is in fluid communication can enable or disable the device seems to be moving. Under the guidelines, the OS is using the shutter button kicks. However, I put my ear to the goal, the operating system of the tower can rest saeeopyi. It 'very quiet, but you can get a microphone on the camera. However, I am satisfied with the image of the cake. Tamron and Canon you and your company / times are you can hear. Therefore, in close collaboration (as Canon does not contain a noise not associated with the operating system and the new lens, Sigma) is.
Rap-Up: Sigma, and a few other little things are the problem, then you have money in the world video, you can get the Canon. Canon Sigma feel better than I, but the purpose of ringcheoreom Canon big difference. The person feels less weight and large hands. However expensive Tamron, caught the ring of focus and feel free e. Shooting video or still, I choose Sigma Tamron
Cons: No FTM 
