"Distortion Correction Software" Mon 10-Jun-13 09:43 AM by mpage
San Jose, US
When I moved from DX to FX, I needed to replace some of my lenses. When I got the a Nikon 17-35 f/2.8 that replaced the Nikon 17-55mm f/2.8 DX lens, I began to notice that there was some distortion that I could not easily fix in Photoshop. I ended up going with DxO Optics Pro, primarily for the ability to correct distortion.
I came across a Zeiss PDF document on distortion recently that is very informative. I thought that others might find it useful:
#2. "RE: Distortion Correction Software" In response to Reply # 1 Mon 10-Jun-13 02:46 AM by mpage
San Jose, US
The article grabbed me right from preface:
“I found somebody say ‘terrible moustache distortion’, but I don’t see any distortion at all”.
As you can see in above statement in a forum discussion one can have very different opinions about distortion of lenses. For some photographers straight lines are of low importance or their subjects don’t have them. Others strive for perfection and spend a lot of efforts, to heal geometric aberrations at least in the image post-processing.
Those who try to avoid these efforts search for lenses which deliver perfect quality right from the beginning without later improvements. At this point the problem with numbers arises, because absolute perfection exists only in a few types. Most lenses exhibit at least small distortion errors, and to decide whether they are acceptable, one has to understand the numbers in data sheets and in lens test publications. This issue of Camera Lens News tries to support you a little bit in understanding this matter.
I spoke with a photographer from a local publication about the distortion and geometric problems with my images shot using the Nikon 17-35mm f/2.8 from at Kentucky Derby party and how pleased I was with the results from DxO Optics Pro. I had them on my iPad and showed him. To my astonishment he thought the images displaying distortion and awkward vertical lines were better. He apparently is among those photographers who "straight lines are of low importance."
I, on the other hand, tend to lean towards the other end of the spectrum, those who "strive for perfection and spend a lot of efforts, to heal geometric aberrations at least in the image post-processing."
#3. "RE: Distortion Correction Software" In response to Reply # 2
Mostly, I just do basic modification, but if I spend my than 5 minutes, it is an important shot!
When setting up to take a shot, I try to avoid having something that needs to be a straight line pass though the outer 1/3rd on the shot, or do so in a way it won't be noticed, which would minimize the distortion.
That said, I have had a time that I used a doorway to frame the shot, and the doorway appeared skinnier at the top! I did run it through an automated lens correction with fixed the shots acceptably, at which point I left it. I still could see some distortion, but only if I was looking for it.
I go by looking at the shot at a glance looks correct, then the distortion is "acceptable". I tend to use FX lenses on my DX bodies, so distortion negligible for the most part.
#4. "RE: Distortion Correction Software" In response to Reply # 3 Tue 09-Jul-13 03:02 AM by mpage
San Jose, US
The first time I used the Nikon 17-35mm f/2.8D lens, I noticed problems with geometry due, in part, to my sloppy shooting technique. Here is an example:
I used DxO to do the rough correction. It took me 20 or 30 seconds to make this correction. I could have done it in Photoshop, but it would have take me much longer. This was only a rough correction. From this point I can tweak the the image more in DxO or take it into Photoshop.