Jump to content

Correcting "Distortion" from the 18mm SEM


Peter Branch

Recommended Posts

Advertisement (gone after registration)

Some while ago I posted a picture, see below, taken with my 18mm SEM to illustrate the use of an Ultra Wide lens with people.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

Significant "distortion" is clearly visible particularly of the lady's face top left.

 

This was a picture from a "first cut" edit as I needed to get a lot of pictures processed quickly.

 

I subsequently edited some of the pictures more carefully - see next post.

Link to post
Share on other sites

Yes- but most of the distortion you see here is from tilting the camera, it exaggerates the perspective distortion you will see on 3D objects in the corners of wideangle lenses (and the scarf does not help either. Turkish ladies have a habit of filling it out ;))

Link to post
Share on other sites

This is the revised edit using the perspective sliders in ACR.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

I don't claim any merit for the picture, the family group simply came and sat down next to me, but it does illustrate that post processing can be a very powerful aid to improving pictures, in this instance removing a form of "distortion", common when using ultra-wide angle lenses, that most people find objectionable.

Link to post
Share on other sites

Yes- but most of the distortion you see here is from tilting the camera, it exaggerates the perspective distortion you will see on 3D object in the corners of wideangle lenses (and the scarf does not help either. Turkish ladies have a habit of filling it out ;))

 

Absolutely, the family by the way are Uzbek, but I had no choice but to point the camera downwards.  The point I'm making is that it is perfectly possible to significantly improve the resulting image by careful use of the controls available in ACR.  In this instance it required both the "Vertical" slider and a significant correction using the "Rotation" slider

Link to post
Share on other sites

Yes, the lens correction tools in Photoshop and ACR are very powerful and useful (I use them a great deal) but your photograph illustrates the basic problem of photographing people with a superwide lens, particularly if you aim to fill the frame in the way you have done. IMO the 'distortion' of the left woman is much more acceptable in the original photograph. In the second, both women look unacceptably squashed vertically (look at the size relationship between the older woman's hand and her head in both photographs). :)

Link to post
Share on other sites

As I said (but we cross-posted I think) this can be corrected as well.

 

It can but there comes a point when you have stretched the pixels in so many ways that the optical qualities of the original (quite expensive) lens seem no longer relevant. Might as well pop one of those wide-angle lens attachments onto an iPhone.  :)

Link to post
Share on other sites

Sorry but just refrain from shooting people up close with anything wider than a 28mm or don't have them in the corner area or shoot with a 16mm Full frame fisheye and live with the distorted lines.

The above eidt is funny looking espc the baby!

 

My thoughts exactly. Peter, you fixed the background nicely but at the expense of both women (the woman in red now looks fat and distorted whilst before just her head was stretched, the hand of the woman in the middle looks even more like she has serious lymphedema) and the baby (which now looks grossly obese).

Link to post
Share on other sites

Thank you to all who have contributed.  The picture below is a third edit making use of the distortion slider.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

It is clear, to me at least, that there is no perfect solution.  Something that I think is an improvement seems quite the opposite to others.

 

When in Uzbekistan I fell into conversation with a member of our tour group who posed the question: " Would you discard a picture because it was not technically perfect?" 

He remarked that he had observed that I seemed to be taking great care over what he perceived were matters relating to technical quality.

 

We had quite a debate, he being a retired professor of mathematics, and came to no real conclusion as to how to define what was worth preserving / discarding.  One of my points was that using modern Leica equipment it seemed appropriate to try to achieve the quality of which it was capable - yes but...........

 

BTW I totally agree with the point that image quality can quite easily be demonstrated to deteriorate if too many PS functions are used.  I can't demonstrate it on the forum because of the picture size limitations etc., but it can be seen on my monitor using *.Tiff files formatted to A3 at 120ppcm.  I can best describe it as a deterioration in the quality of edges.  Easy to correct using sharpening, some might say, but that brings its own set of issues.  

Link to post
Share on other sites

I prefer the original distortion to the attempts to correct it, which just get uglier and uglier. This is how an 18mm lens sees the world - if one doesn't like it, don't use an 18mm.  Personally, I don't have any problem with the 18mm rendering, and really like the picture "as was."

 

Except...

 

I'm very troubled by the degraded contrast and tonality, which has turned three attractive people, dramatically lit, wearing beautifully textured and patterned clothing, into dull, pasty cardboard cutouts. The skin tones are gray, the black embroidery is gray, the wonderful red satin becomes dull cotton, and the headscarves (especially that of the older woman) look like a (semi-successful) attempt at solarization.

 

(See - "solarization": http://joefaraceblogs.com/wp-content/uploads/2011/09/solar.color_1.jpg )

 

Peter, you saw a brilliant situation and captured it beautifully (distortion be d**ned). Then you took your Cordon Bleu image and turned it into weak tea and day-old sausage roll, by destroying the contrast, textures and colors that brought out what was best in the picture. I can't call the posted images "technically perfect" - rather the opposite.

 

There is a much better picture in there - and I can show it to you if it is OK to repost your image, modified.

Link to post
Share on other sites

Peter, you saw a brilliant situation and captured it beautifully (distortion be d**ned). Then you took your Cordon Bleu image and turned it into weak tea and day-old sausage roll, by destroying the contrast, textures and colors that brought out what was best in the picture. I can't call the posted images "technically perfect" - rather the opposite.

 

There is a much better picture in there - and I can show it to you if it is OK to repost your image, modified.

 

I totally agree with adan. In the Original you see, that the photo was taken near to the group of persons. It is mot a portrait from the studio - it is live on street. Look at so many street photos from people with the 21mm in old issues in LFI (former Leica Fotografie) - nobody want's to "correct" it and the were and are beautiful.

 

I often use the 18mm in landscape photography an had never the wish to correct distorsion. Yes, the perspective is (let's say) "strange" compared to normal wide angles but therefore yo use it. The problem is also that you look at "normal" distances to the picture. To get an "original"  look you had to blow up the photo to A2 an watch it from 30cm to see the perspective like the SEM.

Link to post
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...