You can fix converging verticals and other perspective problems in many programs, including Lightroom and DxO Optics Pro, but Capture One Pro 7 has what I think is the most easiest and most accurate tool of all.
The problem with fixing keystoning is that you need to be extremely accurate in aligning the tool’s marker points with vertical lines in your image, and this is where I think you really see the difference between programs. Capture One Pro uses a tiny white dot within a larger circle, and it’s really easy to see and position this almost to pixel-level accuracy.
I’m going to try it out on this picture of the Radcliffe Camera in Oxford which I shot last week.
Anyone who’s been to Oxford will know how difficult it is to photograph this building without introducing strong converging verticals. It’s a tall building in a relatively small square and I had to use a Sigma 10-20mm superwideangle to fit it all in – but I also had to tilt the camera, which is why I’ve got these really strong and undesirable converging verticals.
01 Lens corrections
Before you carry out any perspective corrections, it’s really useful to correct any barrel distortion from your wideangle lens. If you don’t, straight lines near the edge of the frame will appear bowed, which will make it difficult to line up the perspective correction tool accurately.
Capture One Pro 7 introduces new automatic lens correction profiles. Usually it will detect the correct profile automatically from the image’s EXIF metadata (shooting information), but that didn’t work this time, so I used the drop-down profile menu in the Lens tool tab instead.
The lens I used – the Sigma 10-20mm – appears on the list but only in the Canon version, whereas I was shooting with a Nikon D-SLR. Never mind, the corrections should be the same, so this is the profile I select, and straight away I can see the difference, where the picture’s slight barrel distortion has been straightened out.
Don’t forget – you can click on any image to see a larger version.
02 The Keystone Vertical tool
So now I can select the Keystone Vertical tool on the top toolbar. This places two vertical lines on the image, each of which has two circular ‘crosshair’ gadgets.