LR Distortion Correction Profile for Canon 16-35mm F:4

[David Eichler]

I am finding that the distortion correction profile for this lens consistently undercorrects for rectilinear distortion throughout much or all of the lens's range. Anyone else experiencing this with this or any other lenses? I am not sure any distortion correction profile is perfect in all situations with any lens, and I can usually finish the job with a small amount of additional correction with the distortion slider, but it would be nice if the profile could get consistently closer to full correction.

[phila]

I'm finding I need to use about -4 to correct barrel distortion...

[pluton]

The distortion correction for my Nikon 17-35 is junk also;  it introduces pincushion distortion that is worse than the barrel distortion it is supposed to correct.

[AFairley]

Eric Chan has said that the Adobe lens corrections tend to be conservative.  It's relatively easy to use the Adobe Lens Profile creator to make your own profile that should smooth out over- or under-correction.  Someone else may have done it before you and uploaded the profile in which case you can download it with the profile Downloader app.

[David Eichler]

Eric Chan has said that the Adobe lens corrections tend to be conservative.  It's relatively easy to use the Adobe Lens Profile creator to make your own profile that should smooth out over- or under-correction.  Someone else may have done it before you and uploaded the profile in which case you can download it with the profile Downloader app.

Not always so conservative. With the Canon 17-40mm and the 16-35mm F:4, I find the Adobe profiles tend to overcorrect for vignetting.

[alan_b]

Problem is that most of these lenses have distortion that varies w/ focus distance.  In order to shoot test images at working distances, you'd need a building-size target chart for super-wide lenses.  PTLens or PTGui is much more practical for me.

[David Eichler]

Problem is that most of these lenses have distortion that varies w/ focus distance.  In order to shoot test images at working distances, you'd need a building-size target chart for super-wide lenses.  PTLens or PTGui is much more practical for me.

Of course. And rectilinear distortion also varies with the distance from the object to the camera, regardless of the point of focus. So, no distortion correction profile can be perfect.

Haven't used PTLens in a long time. Will have to revisit.

[AFairley]

Of course. And rectilinear distortion also varies with the distance from the object to the camera, regardless of the point of focus. So, no distortion correction profile can be perfect.

Are you sure?  Perspective distortion, yes, but I would have that that rectilinear distortion would be the same at the same point in the field of view at any distance.   

I had thought that shooting targets at different focal distances with the Adobe target was more for CA and vignetting correction.

[pluton]

Problem is that most of these lenses have distortion that varies w/ focus distance.  In order to shoot test images at working distances, you'd need a building-size target chart for super-wide lenses.  PTLens or PTGui is much more practical for me.

+1 on the building-sized test charts.