Originally posted by ElJamoquio
Different coatings, in my opinion, often makes for a rebadge. With modern coatings the difference between 99% and 99.2% is primarily marketing. Different outer shell = Rebadge IMO
Originally posted by mikemike
I agree, but it is quite plausible that one brand might use better grades of glass for their elements or use better types of elements like with aspherical elements using ground glass instead of molded or hybrid. It is probably impossible to tell for certain though without it being expressly noted or taking the lenses apart and inspecting the elements by someone who is an expert in optical glass.
The real question is whether the lenses perform the same in terms of real world output. Coatings and quality of glass can affect microcnotrast and color rendition, both of which can have a bigger impact on image quality than, say, sensor size, because the effects of microcontrast and color rendition can be detected at small prints sizes, whereas it might require large print sizes before you'll notice the added resolution due to larger sensor size.
According to lenstip.com, theTokina 12-24 has a "green hole," which means it prevents a larger percentage of the green part of the color spectrum from reaching the sensor than most lenses in its price category. That potentially lowers the quality of the color rendition, which can have an impact on the final image, particularly prints.The DA 12-24, on the other hand, suffers no such "green hole" problems. It has some of the best color rendering of green (and blue) that I've ever seen in a zoom lens.