Did no one post any reviews of this. The price is just too much, would buy an EF one and adaptor.
It's hard to fully review this lens right now because it's not supported in Lightroom, and I refuse to use Canon DPP software to edit any of my actual work. What I can say so far from my experience with the lens this past month or so, roughly, is that this lens is worth the price for me. The only negative attributes to this lens are its price and the uncorrected distortion (which actually comes with a tangible strength). The list of positives is extremely lengthly and, at least for me, help justify the price. I'm currently using the RF 24-105 f/4-7.1 lens profile for distortion correction and it works really well for images shot wider than 17mm, but it's not perfect and over-corrects beyond that....so I(we) really need an Adobe profile because it's how I work.
From a sharpness standpoint, this is a very VERY sharp lens - all the way into the corners wide open, I don't know where people are getting off saying it's not sharp because they've clearly had no experience with it. 14mm is extremely useful and I personally have been wanting something just a little bit wider and almost jumped on the 15-35...but I'm glad I waited. The minimum focusing distance is also very useful. The flare control is brilliant and takes on a very beautiful aesthetic that I honestly think looks like a prime lens. The image stabilization paired with the R5/R6 is rock solid and bests my 24-105...but it's also wide, so it should. Size and weight...wow, thank you Canon - it's perfect!
Let's talk about these "negatives" because they are directly linked, IMO.
At this price, which I admit is higher than I believe it should be, you would expect and should expect an optically perfect lens. We didn't get that here...Canon made obvious compromises in the design to allow the use for screw-on filters...and I'm OK with that. I refuse to buy bulbous front element lenses. But because of these compromises, the lens requires correction in post to work correctly. It was designed from the ground up for this and uses some of the best quality glass in the world to compensate for the "stretching" that will occur in software or in camera for JPEGs. There are THREE Aspherical elements in the design, two are glass-moulded and these are not cheap to produce in addition to the coatings. Canon threw the kitchen sink at this thing to make sure the optical performance survived correction with minimal deterioration. This design comes with a really great benefit - 14mm wide-angle shots with a 77mm CPL or ND filter WITHOUT seeing the filter vignette. This is possible because the corners are essentially thrown away. A common misconception with this lens is that it's a 16mm after correction, this is totally incorrect. This is more realistically a 12mm lens that "flattens" out to a 14mm lens. The worst parts of the image are removed and you're only left with the good stuff.
If you can pay the price and use wide angle lenses on a tripod a lot like me, I don't think there is a better option out there for Canon. I can't wait to unload my EF 16-35mm f/2.8L III USM on the used market because this lens is everything I need and more for my work.
The price is wrong. The performance is world-class.