Comparing Lens Correction Profile Software
I should mention first that some of the crops look smaller than others. This is to show what happens when lens correction is applied and how much of the original image is lost. Photoshop/Lightroom loses the most, and frankly is not all that impressive compared to the others. However it does some of the CA and distortion correction, but at a huge cost of the field of view.
Lightroom/Photoshop via Adobe Camera Raw shows some limitations here. In the stock profiles, the images are still exhibiting strong CA and requires further intervention. This particular lens has a lot of lens variations, so when the settings were tweaked a little further, the results were much closer to what PTLens produces.
PT Lens does a pretty good job of fixing both distortion and CA. It also loses only a minor amount of the original field of view. it however has some alignment issues still so it's still not perfect.
DxO Optics is by far the best one. This is what equalizes the 16-35 with a prime lens like the Samyang 14mm in this respect. The field of view of course is different but it does show that with the right software that some of the problems that a zoom lenses exhibits can be fixed very well with software. It doesn't mean that it can replace a good prime, but what it does show is that if you want to use a zoom lens like the 16-35mm there are options to improve it without too much sacrifice to image quality.
Overall, the most economical choice is PTLens especially if you use Photoshop in your photography workflow, however DxO is clearly the superior choice here. The caveat with DxO Optics is that there's no third party profiles that can be added like Adobe Lightroom. Lightroom's approach is far more open and has a community of contributors that have created profiles for various lenses. From a general RAW processing point of view, I prefer DxO Optics about 80% of the time and because of that, I recommend it's Lens Correction Profile for problematic images. Also DxO Optics does a far superior job with perspective correction and control over Lightroom or Photoshop. Geometry seems far less distorted and closer to what I'd expect from a tilt-shift lens.
DxO Optics can be purchased directly from their web site available in two versions, the Standard ($169 USD) and the Elite ($299 USD) Editions. The Trial Version can be download here for a limited period of time with no limitations or watermarks.
Adobe Photoshop Lightroom can be purchased directly from their web site for $299 USD and the Trial Version can be download here which also offers no limitations or watermarks.
PTLens can be found online at their web site for $25 USD. Comes with a standalone application and also a plug-in for Adobe Photoshop.