Tamron’s image stabilization (VC) works exceptionally good. The Tamron had serious vignetting issues at 2.8 (along the whole zoom range). At F4 and above vignetting was no longer an issue. In the center of the frame Canon’s lens is always slightly sharper and at 24mm the edges were significantly sharper than the Tamron SP 24-70mm f/2.8 DI My 70-200mm f/4 is a heck of a lot lighter. As for the optics, the 17-55mm does have very good optics, but the 24-70mm clearly outperforms it both wide open (f/2.8) and the sharpness covers more of the frame, with sharpness dropping off 15mm from the centre of the image, whereas the 17-55mm starts dropping sharpness immediately. Canon EF 70-300mm f/4.5-5.6 DO IS Vello ET-65B Lens Hood f/Canon LHC-ET65B Pearstone 58mm Snap-on Tulip Lens Hood 10042430 Canon EF 85mm f/1.8 Vello ET-65III Lens Hood f/Canon LHC-ET65III Pearstone 58mm Snap-on Tulip Lens Hood 10042430 Canon EF 100mm f/2.8 Macro Vello ET-67 Lens Hood f/Canon LHC-ET67 67mm Snap-on Tulip Lens Hood (Version II Has rounded aperture blades. Sony FE 24-105mm f/4 G OSS. Tamron 17-70mm f/2.8 Di III-A VC RXD. Similar to the number of aperture blades, rounded blades affect the way the light gets through to the sensor. Rounded blades, often only found on more expensive lenses, improve the appearance of the out-of-focus areas. Has a metal mount. Canon EF 24-70mm F/2.8L II USM. Canon EF-S 18-135mm F/3.5-5.6 IS STM. A metal mount is generally superior to a plastic mount as it is more durable. weight. 805g. 480g. We consider a lower weight better because lighter devices are more comfortable to carry. Crop the Tamron at 180mm a little and your image will be sharper and more detailed than the Sony at 200 mm. 180 vs 200mm is so minimal difference. There is good YouTube videos on Tammy 180mm vs Sony 200mm. I'd take a 70-180mm at f/2.8 all day over a 70-200mm at f4. Wow, never knew its a bad lens, let alone one of the worse. The Tammy it is! Something like the EF 400mm f/5.6 L USM, or EF 500mm f/4 L IS II USM, or maybe the EF 300mm f/2.8 L IS II combined with a Canon EF 1.4x III or EF 2x III Extender. If you use an extender, you will need a wide aperture lens so your camera will still Auto Focus with the extra stop (1.4x) or two stops (2x) of aperture the extender will cost you. Hi, I would go with the f/2.8 aperture. Shooting a crop sensor in a dim theater I would really like more than f/4 to work with. Compare the 80d and 60d in high ISO on DXO mark. The improvement is not huge. The 24-70 is by all accounts a beautiful and sharp lens. On a budget you might consider 9arCyS.