Category Archives: Photography

Lens Compression and Lens Distortion

(Originally published 2016-03-16 as /archives/10930)

This lens-compression-thing: we all agree on it correct?

Lens Compression

The definition of lens compression is this: if you use a longer focal length, then the background will appear to be closer to the subject. There are numerous examples of images that “prove” this out there (including the GIF below), but guess what? Lens compression doesn’t actually exist.

Here’s how the prove-it examples work:

  1. First the photographer makes a photo of a subject, standing in front of a background object, with a short focal length lens (wide angle, less magnification).
  2. Then the photographer takes the same picture, of the same subject, at the same distance from the camera, but with a longer focal length lens (telephoto, more magnification).
  3. Then we compare the two images, and note that the background object appears to be closer to the subject in image #2.Here’s the kicker:
  4. If we then crop image #1, so that the subject takes up the same amount of space in each image, we will note that the subject now looks to be the same exact distance from the background object as in image #2.

In other words: lens compression is just an optical illusion.

Lens distortion

Barrel Distortion, Pincushioning, Bokeh, etc., may be different with each of the two lenses. Generally the wider angle lens (shorter focal length, less magnification) will distort the image more and cause more foreshortening relative to the telephoto lens (longer focal length, more magnification), but not always. A lot depends on lens design, and post processing software is really good at removing distortion these days.

The following GIF was shared at “reddit /r/educationalgifs How different lenses affect portraits“. It shows the foreshortening issue and the so-called-lens-compression-issue at various focal lengths of a telephoto super zoom lens. For many people this will be proof that lens compression is real. It still isn’t real, and not all wide angle lenses will cause such drastic foreshortening.

OK: so if the focal length is changing, then why is the subject’s head mostly the same size? Because the photographer is moving physically closer to the subject, for the wider angle shots, and farther away for the telephoto shots.

Here’s the GIF:
XBIOEvZ - Imgur

Back to the Lens Compression Example

OK, so Paul must be wrong about lens compression. I mean look at how that tree in the background of that GIF moves closer to the subject: right?

In the following video, Dieter Schneider does the steps (from above) to prove that lens compression does not exist.

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Scott Kelby: Two Lights, One White Background

(Originally published on 2016-03-28 as /archives/10922)

Scott Kelby made this video for Westcott, but it’s good information for everyone.

The next step would be to consider adding weak lights behind the subject: either to light-up the background, or to highlight the subject’s hair. A third light isn’t needed here, because the white backdrop reflects so much light.

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Free Portrait Guides

(Originally posted on 2016-05-06)

IMG_9611
(The posing and lighting guides are below.)

The “Hers” blog Facebook page has a “Posing for one” guide.  I think that the negative reader comments are interesting:

The right way to make some one look better ????? In who’s eyes !!! That’s awful I’m sorry but this wrong on so many levels…so thinner arms make the shot better ??? Really come on this is hiding who you really are it’s as bad as photoshop …if you have fat arms or belly or bum so what you don’t look any less sexy ..in fact if you show your flaws and own them with confidence there is nothing more beautiful or sexy than that !!!!fact!!!!

This is silly. People, love yourselves for who you are, not for what you think is the socially acceptable version of beauty.

She looks thin whatever pose she makes cause SHE.IS.THIN

When you put a set of images in front of a subject, which ones do they want? The ones with the better poses. Plus: posing-well is easier, and more accurate, than digital editing.

Here are some posing and portrait guides from Digital Camera World:

 

 

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onOne Photo Editing: Masking Trees

(Originally posted on Mar 13, 2016 as /archives/10878)

onOne has a good video on how to make complex masks.

The video exclusively uses the onOne Photo 10 suite. Instead I copy the new mask from onOne into Photoshop and use it there. I find that easier to do than using Photoshop’s masking tools, and it’s more flexible than limiting myself to onOne’s suite.

I usually only post videos that I need to use in the future. That means that you won’t see the most common photography and post processing tasks here. Those are easy enough to find via Google.

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White Balance Does Not Work The Way That They Say, Maybe Not For You, Definitely Not For Me

(Original posting date: 2016-07-27)

Spiritia [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
It’s quite common for photography writers to write something like, “The human eye… adjusts the colors you see,” whenever discussing white balance. I never encountered one of these articles that also referred to scientific research, and I am unsatisfied with the explanation.

For one thing: it’s not consistent with anything that I learned in physiological psychology or psychophysics regarding vision.

For another thing: it is extremely common for scientific-thinking people to disprove much of what photographers teach.

By Håkan Bergknut (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

For another: it’s not consistent with my personal experience, which is more like this:

I don’t believe that my “human eye… adjusts the colours [I] see.” I am very aware of color temperature. I suspect that most photographers develop this awareness, and some people have always had it.

When I am in an environment with soft white light, that’s what I see, but it’s everywhere. It’s even affecting the color of the photos on my wall. If those were white balanced, then the light from the too-warm bulbs is affecting the colors of those photos exactly the same way that it’s affecting everything else in the room, so it’s tolerably similar, but not changed by my eyes.

I left that as a comment on a Picture Correct article on white balance, and Wendy disagreed, but her rebuttal is not actually inconsistent with my comment above. She wrote:

Some say it’s the “eye” that adjusts, some say it’s in the “brain,” point is, you DO adjust to a “normal” WB. If you’ve been inside with a bunch of tungsten–especially low-light, like in a theater–and then suddenly go outside, the world will be blue-shifted for a few seconds while you adjust.

I make temari (embroidered thread balls), and I’ve got one that’s got a design in blue and three shades of purple. Thing is, in dim light, your eyes will try to convince you it’s red, yellow, green and blue–that you’re just seeing it in a different “white balance” than you really are.

She gives an example of an adjustment here, but I am not convinced it is. To me it looks like an example of becoming aware of the different colors of light, but I am always aware of them, and people that think about light will be too.

The “human eye adjusts” isn’t a scientific explanation, it’s an expectation. Photographers think about white balance this way, because that’s what they have been taught, but in reality, they do see three shades of purple as non-purple, because there’s no real adjusting going on.

That said: adjusting white balance in your image is important, because the colors in your photo are affected by the light that you are viewing it in, exactly as much as every other color that’s in that same light. Your photos won’t look “right”.

On the other hand, by all means: monkey with white balance in order to meet your artistic goals.

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“The Dress” (The Only 100% Accurate Explanation)

(Originally written in February of 2015 as /archives/date/2015/02)

tumblr_nkcjuq8Tdr1tnacy1o1_500
The original image.

Would black look gold without an optical illusion?

Some are saying that it’s a color constancy illusion. I will attempt to prove that’s not the case.

Bleached-blue could look white, and bleached-black could look golden-brown.

Each pixel may have a different color, but Photoshop’s color picker can do a 51 x 51 pixel average for us to get a more accurate estimate. In this version of the image, the golden section of the darker-colored stripes’ RGB values are:

  • Red: 121
  • Green: 106
  • Blue: 71

These values are like “shadow”, which is a golden brown. If our perception matches the actual technical colors, then we are not dealing with an optical illusion.

Why are the colors wrong?

Here is where the real problem lies:

Most people say that it’s white and gold.

tumblr_nkcjuq8Tdr1tnacy1o1_500
The original image.

On Buzzfeed 68% say “white and gold”, and 32% say “black and blue”.

Color Calibration?

Monitors are not color calibrated from the factory, so many people are not seeing accurate color.

Was the image white balanced?

We would hope to find white balance information in the image’s EXIF, but it’s not there. So how do we white balance this image? The dress in the background looks white and black. I loaded the image up in Lightroom, and used that assumption to white balance it. If you would like to try this out yourself, here’s how to do it. The black I used is in the lower left corner. We can all agree-that that’s supposed be black: correct? 🙂

With the white balance "fixed".
With the white balance “fixed”.

Is the image accurately toned?

Lightroom shows us that we might have blown out colors. How do we know that this is real clipping, instead of a false positive? The light has softened the edges of the dress so much that it looks foggy in there. So, yes, this a blown out image. If we were there, then we would have a well-exposed the image, but we weren’t, so we are going to adjust tone to even out the histogram.

With the tone "fixed".
With the tone “fixed”.

So what is our best guess for the color? Black and Blue

Each pixel may have a different color, but Photoshop’s color picker can do a 51 x 51 pixel average for us to get a more accurate estimate.

The lighter colored stripes have a lot of blue:

  • Red: 8
  • Green: 77
  • Blue: 206

In other words: blue.

The darker colored stripes RGB values are close to zero:

  • Red: 1
  • Green: 8
  • Blue: 49

In other words: black.

Conclusion

A skilled photographer would could set its white balance and its tone. Once we do that, it’s blue and black. Here’s the final word:

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