PTLens
Sunday, August 23rd, 2009
I’m experimenting with an application called PTLens which corrects pincushion/barrel distortion, vignetting, chromatic aberration, and perspective.
In this case, the 24mm end of the Canon EF 24-70mm f/2.8L causes distortion in the perspective on buildings left and right of center.
Before:
After:
The image would need to be cropped to remove the black areas left and right of bottom center.
I heard about this application from one of my favorite photobloggers, Sam Javanrouh who no doubt uses it a lot on his wide angle urban landscape images.
wow, i need to check my Sigma 24-70 to see if the same distortion occurs!
Dilip: This kind of distortion is common in wide angle lenses. Some of the newer models of older lenses do a lot to correct for it. The Canon 16-35mm f/2.8 II and the Canon 14mm f/2.8 II are two newer versions that are supposed to do this.
No lens is perfect and no doubt a program like PTLens will be needed unless one uses a tilt-shift lens which is built to handle these types of distortions (or accentuate them).
PTLens is quite popular, and a good solution for those who don’t have Photoshop in their arsenal (which has a similar tool). And some prefer PTLens to the Photoshop tool, so use it as a plugin to Photoshop. Great example here of how these tools help those of us without lenses or cameras with built-in movements.
And as you mention, Richard, I can confirm that the 16-35mm f/2.8 mkII does control distortion better than the 24-70mm f/2.8. I suspect that there will be an update to the latter before too very long. It seems more than due. I love the Canon 24-70mm L, but I would love to see an updated version with some more correction, etc.
Dale: Well, you’re the one who got me thinking about this image. I still have your corrected version and might have posted it here as a second alternative as I think you and/or the tool you used did a better job. However, I’m so new at this that my use of PTLens is no demonstration of it’s power or usefulness. In time I might improve some.
So, you think our 24-70 is getting long in the tooth ‘eh? I do love that lens but using it on the wide end can be problematic at times.
Love those distorted buildings…
wasn’t there a famous Spanish architect who made his buildings a little off-kilter on purpose? who was that guy..?
sheryl: Lots of architects are doing off kilter these days, for instance, Frank Gehry, among others. Are you talking about Gaudi, the Spanish artist?
Richard: the quick process that I did on that image was done in Photoshop CS3 from a JPEG. CS4 has numerous improvements in certain tools, such as Photomerge, etc., but I’m not sure if they tweaked the lens perspective tools. PTLens has the advantage of using “profiles” for specific Camera and Lens combinations, which PS does not. Those Photoshop users who use this type of tool often seem to go for PTLens as a plug-in for Photoshop (as an on-board option), and it’s great that a stand-alone option is available for those not using Photoshop.
I think it’s fair to say that the 24-70mm L is growing “long in the tooth”, but that in no way suggests that it should be sent to pasture. The lens is THE workhorse for photojournalists and does well in many other applications, as you know. I carried a camera with only the 24-70 mounted today. But IMO if those at Canon are on the ball, they’ll be tweaking this great f/2.8 zoom sooner rather than later. Digital imaging puts different demands on lenses, and the new sensors can apply additional “pressures”.
Dale, thanks for reminding me to actually pay for PTLens, I think it will prove useful from time to time.
I hope there is an update to the 24-70 but I’m afraid of what its price might be given that Canon seems to be creating artificial shortages to keep their prices high. Time will tell.