08 March 2017

Decorating corners

Grab the adornments

Statue without vignette
Statue staring into nothingess
Of course, I should have continued with a new post about lenses, as we were not finished with that. But instead I decided to talk about decorations. In this case about "decorative design". So, grab the garlands and the balloons and start decorating your camera, to get the better photos!
If you're not in a festive mood, you can also read on and hear more about these "decorative designs". I actually checked the word I wanted to talk about, and found the origin of it on thesaurus.com:
vignette 1751, "decorative design,"originally a design in the form of vinetendrils around the borders of a book page, especially a picture page, from Fr.vignette, from O.Fr., dim. of vigne"vineyard" (see vine). Sense transferred from the border to the picture itself, then(1853) to a type of small photographic portrait with blurred edges very popular mid-19c. Meaning "literary sketch" is first recorded 1880, probably from the photographic sense.

In the sense of photography however, vignette has nothing to do with vines. In photography we talk about vignetting when the corners are darker. And there could also be a small distortion in the corners. There are multiple types of vignetting:
  1. Artificial vignetting
  2. Optical vignetting (also called natural vignetting)
  3. Pixel vignetting
  4. Mechanical vignetting
In general you do not want vignetting, and lens manufacturers do their best to keep this to a minimum. Just as camera manufacturers can build in software to reduce vignetting. This software works well for JPG, but has no influence on RAW. Well, I found that comment online. It said it would work with the manufacturers specific software, like Capture NX 2 for Nikon. But less specific tools like Aperture or Lightroom don't use that information.
Statue with vignette
Statue now staring at the void
How do you recognize a vignette? Easy, just look at the first photo with that statue staring into nothingness. Let's take that as the example without vignette.
Now compare that to the same photo which has one, where the statue is now staring into the void. Of course, I did cheat and did put this exaggerated vignette on it. However, it should serve its purpose to see a vignetted photo. If a modern camera or lens would create a vignette like this, it would be time to return it to the manufacturer.

Away with that black

So, do we always want to remove vignetting? Apparently not, as the first type of vignetting is aptly named "artificial vignetting". And that means that the photographer did put it there on purpose. Just like I did with the example. There will probably always be discussions whether this is "good" or "bad", but I think that is simply for the photographer to decide. That means you! From me you will not receive many nasty comments about an applied vignette. In fact, I am in the group of people that actually like vignetting. Not as much as done in this example, but the original also has a little vignetting applied. So why would you do that?
For me: I tend to like slightly darker photos. When post processing I am almost always turning down the highlights and whites. And a subtle vignette does darken the feeling of a photo. How do I know I like darker images? Well, obviously, because of the histogram.
Histogram
Histogram, exposed to the left
Many of my photos turn out to have a histogram like the one shown. On the left are the dark colors, on the right the bright colors. And as you can see, there is a lot of dark in the photo I used for this. (The histogram is not from the photo with the statue.)
When you have a lot of your photos with such histograms, you probably like darker photos. Just like me.
After this small detour about histograms, back to the vignetting. I said it darkens the feel of a photo. Naturally it does more than darken the feeling, it actually darkens the corners after all. There is also another aspect to that, though. Look again at the two photos. Do you notice how the vignette forces your view towards the center? This vignetting works fine with the subject in the center. If the more important parts of your photo are near the edges, well congratulations, a vignette like this has just ruined your shot.
Anyway, keep in mind that vignetting is often considered bad. And if your camera or lens produces heavy vignettes, it probably is bad. But vignetting is sometimes done on purpose.

Why do I get this black?

This part goes about optical vignetting. And this is also the one that the manufacturers are trying to reduce as much as possible. For you, as photographer, there is not much to do about it. The cause is how the light enters the lens. When the light comes from an extreme angle, it travels a longer distance through the lens towards the sensor. Longer travel means more "falloff", or said for a noob like me: less bright light reaches the sensor.
Also, the light entering at these extreme angles is partially blocked by the lens barrel. You can see at your camera that the lens is not totally at the front. Luckily as it otherwise might just drop off. There is usually a small part of the barrel sticking out and that partially blocks the light coming from the extreme sides.
 Lenses with a long focal length are less susceptible to this effect than the ultra-wide angle lenses. You could also see if stepping down the aperture (higher F-stop) helps.
The way the light travels through the lens, is also the cause for the distortion, turning f.e. round bokeh into the shape of a cat's eye pupil.

What is pixel vignetting?

Pixel vignetting is a bit like optical vignetting, but instead of having to do with your lens or how far the light travels, it is about how it hits the sensor. The sensor is the retina of the camera. In the human eye, the light comes through your pupil then goes through the lens, so we can focus on something. The light then falls on the retina, where the cones (colors) and rods (light intensity) translate the image to electrical signals to our brain. The sensor in the camera captures the light that falls on it and then translates that to a digital photo, with for each channel (red, green, blue) an intensity value.
If you find a volunteer to examine his or her eye, please do refrain from that. In most countries it is not allowed to poke people in the eyes and starting to examine it. Not even when you get permission. It also tends to lead to permanent damage, called blindness.
Anyway, the sensor in the camera is flat and all the pixels on the sensor are facing the same direction. probably perfect for light that falls straight on it/ Which would mostly be the case for pixels in the center of the sensor. When light comes from an angle, slightly less light falls on the pixel and that also introduces a little vignette.

Let's get to the mechanics

Last we have mechanical vignetting. And I kept this last, as it's also the easiest to understand. it means that something is blocking the light. Like a lens hood. Manufacturers do think about the shape of their lens hoods and using another one could lead to more mechanical vignetting, as it blocks more light.
But also the stacking of filters, teleconverters, extension tubes or other accessories that diminishes light in the corners are called mechanical vignetting.

I have white corners

Statue dreaming away
Statue dreaming away
This vignette has no black corners, but white. And that means all the explanations about light traveling, angles and whatever are not suitable. In fact, the only suitable answer left is the artificial vignette.
And indeed, instead of a black vignette, most post-processing software also allows you to make a white vignette. While a black vignette darkens a photo, a white vignette lightens it. It only actually lightens the corners, but as an effect the whole photo feels more lightened.
I personally find that, although it does turn the attention more towards the center, it lacks the strength that a black vignette has. Yet, this type of vignette has a usage where photos are supposed to be more "dreamy". To me it feels softer than a black vignette.
In general a white vignette works well with an already bright photo, or to camouflage a bright sun flare on one side of the photo, by brightening up all sides. A black vignette adds more drama or mood.

Now, when you want to add vignettes, do remember that the effect can be used subtly. Not every photo needs or becomes better by using the maximum vignette that your software allows. Of course, the strength of vignetting and the choice of using it at all, is totally yours. I personally like them and most of my photos have a black vignette. Also keep in mind that in post-processing a vignette does not always need to be centered.

So, what is your opinion about the usage of vignettes? Do you use them? Do you like them? If you had to use one, would you pick the black or white vignette on the statue? Or would you prefer that all vignettes photos should be burned?