Distortion issue

[Philip Freedman]

I have a 5D and a 50/1.8, a 35/1.4L and 24-105/4L. I am going to Venice and am

planning a project around old buildings, windows, walls etc and need minimum

distortion. I tried out each of my lenses on a windowframe at home and was

surprised to find that the zoom set at around 35mm showed much less obvious

distortion than the 50 or 35L (which both showed noticeable barrel distortion)

but would still need some attention in Photoshop or perhaps a dedicated

software package such as DxO. Any ideas?

 

Thanks Philip

[peter_houtmeyers]

If you dont want to be working a lot with photoshop after your trip to Venice, you could consider buying a 24mm or 45mm tilt and shift lens. Most software applications used for correcting lensdistortions degrade the image quality.

[wilbur_wong]

I use PT Lens you can try it free if you like. Purchase price is $15.

 

Here's the link: http://epaperpress.com/ptlens/index.html

 

It does a great job with barrel / pincushion on my 24 - 105 images used as a plug in in photoshop.

[ben_goren]

Peter's got the right answer -- the TS-E lenses -- but they're about $1K each. If you need a

distortion-free 50mm, consider the 50mm f/2.5 macro.

 

I've never noticed any distortion with my 50 mm f/1.8 II...but I've pretty much only used it for

non-geometrical subjects on a crop sensor.

 

Cheers,

 

b&

[robin_sibson1]

I think some respondents to the original question may be confusing distortion as a lens defect (barrel/pincushion distortion) with the management of converging/diverging verticals and with the 'distortion' effect of wide-angle lenses (which arises because the image is viewed differently from the way it is taken). My understanding of the question is that it is purely about pincushion/barrel distortion. The first answer is to choose lenses with negligible distortion like the 50/2.5 and 100/2.8USM, but that's not a very helpful answer if you already have your lenses. The second answer is to correct for the distortion during post-processing, and the most economical way of doing that is to use the PTLens plug-in with Photoshop Elements. DxO is a much more expensive option.

 

You would probably make much use of the TS-E 24mm lens for your project if you bought one. It actually has very low distortion, but the real attraction is the shift capability for work of this kind.

[wilbur_wong]

Robin is very correct about the posters question. Perspective correction is a different issue from curved lines. For serious architectural work, I use a 4 x 5 view camera, however for quick field work the 5D is a great walk around tool. The perspective issues can be relatively easily addressed with Photoshop tools, but the distortions are much more easily addressed with the already calibrated profiles available in PT Lens.

[ben_goren]

Not only are the TS-E lenses capable of correcting perspective distortion, but they also

have the minimal barrel / pincushion distortion that Philip is specifically seeking. That's

why I called them ``the right answer.'' They solve his immediate problem, as well as the

next several problems he'll have, as well.

 

The 50mm macro solves the immediate problem and is a lot cheaper, which is why I

recommended it. But it's just a stop-gap for the kind of photography Philip is describing.

 

Cheers,

 

b&

[jon_austin]

The PTLens program (standalone or Photoshop plugin), in addition to lens distortion, can also correct for vertical and horizontal perspective, rotation, and chromatic aberrations. However, as Peter rightly noted, any software solution will degrade image quality. Still, it's a heck of a lot cheaper than a T/S lens. Just depends on your budget and your quality requirements.

[keith_lubow]

Doing the equivalent of a rear tilt or swing is best done in the camera as much as possible, not the enlarger or Photoshop. When you adjust the image like that after the fact, some parts of the image are resampled differently than other parts of the image. Sure people do it all the time, but for best results, a tilt-shift lens would give you the best quality. This being said, it is too bad that you are forced to use 35 format for this project instead of large format.

 

Keith

[ymages]

TSE 24 is a great lens, certainly the best for that kind of works

PT Lens is a very good tool but you will never get the same

[george_mazzetti1]

Photo

shop Elements 5.0 has a wonderful distortion control plug-in that is easy to use. Send me one of your files and I'll work on it and send it back to you.

 

George Mazzetti

[JDMvW]

No real substitute for view camera with tilts/shifts front and back. That having been said, digital is really much better in terms of being sure you've got what you went to get. If you're going all the the way to Venice, then you really need to consider either the 24 or 35mm TSE lens. Honestly, the tilt is not as significant as the shift, but both are very nice. An alternative, given that the TSEs are manual anyway, is to buy a nice old PC Nikkor (28 or 35mm, shift only) and a Nikon>EOS adapter. I've used my PC-Nikkor on my 20D, but alas there it is a normal, not wide angle, equivalent. With the 5D you're in like Flynn (specializing in out-of-date expressions since I got old).