>>2882119The IS version adds image stabilization, if you would test both in a studio setting you wouldn't notice a difference in image quality.
The IS and the 2.8 version help you to deal with less than optimal light situations, only you know what you shoot with it and if you might end up in situations where you might need the extra f stop or Image stabilization. If you continue shooting scenery and architecture you have a lot of control over your shot and might just need a tripod, then you wouldn't need the IS obviously.
Keep in mind that Canon is not the only brand making great lenses. The Sigma and Tamron alternatives cost just a fraction and you won't notice a big difference in most cases.
I tested the Tamron on a festival and it was great. Just as fast and sharp as the Canon, no problems focusing the dancing people though the festival mist. Pic related is the Tamron at 2.8, this is 100% zoomed in.
