Yup, it implies that current coatings are better than something that came out in 2005. Canon's 24-70 f/4 IS has a t-stop = 4. The 24-70 II has a t-stop of 3 while the version I has a t-stop of 3.4.AJ said:Isn't the point of lens design to have optimal light transmission? And if the f-stop is four and the t-stop half a stop worse, doesn't that say something about Canon's glass elements and coatings? The Canon 24-105 is a good lens but it should not have been branded with the red ring.Zv said:An f/4 zoom lens is not one you'd expect to have optimal light transmission anyway.