Following on …

After my long, complicated post on 4th Feb, I left myself exhausted; informed, but exhausted.  Today I feel the need to cement some of the theory I learnt and just reconfirm some information surrounding Tonal Range, Contrast and Dynamic Range and how they all fit together in photography.

What is Tonal Range?

I feel like I only really touched on this subject in my last post, and think that I missed quiet a lot of information out of my writings, not really explaining Tonal Range in full, or if I did, it was a little muddled and perhaps lost-in-translation.  It isn’t really a difficult subject to grasp, as Tonal Range depicts the various shades of grey that appear between absolute white and absolute black, and within a photograph, this range of tones is known as ‘a scenes dynamic range’, which was outlined in my previous post.

Freeman (2008) and Eftaiha (2011) both state that the Tonal Range within a photograph is not only dependent on the subject matter within the image, but is also dependent on the available light at the time of shooting and whether other factors such as diffusers, filters and artificial light sources are being added to the mix.

As photographers, it should always be our intention to take a photo that represents what we see in the scene.  Our eyes are better equipped to do this naturally, but our camera sometimes needs a little assistance in this replication.

Most photos will fall within the three average Tonal Ranges, which are 1) Average Tonal Range, were all areas of the image are lit the same and are neither dark or light; 2) Dark Tonal Range, which include images where the key subject of the image has darker tones, and the surrounding area in the frame could be darker also and 3) Light Tonal Range, which include images where the key subject has lighter tones, as does some, if not all of the surrounding area within the image.  These last two image types are also known as High (light) and Low (dark) Key images, which was also covered in my previous post.

We previously discussed that within photography Tonal Range refers to the expanding values of mid-tones between the darkest (0 value) and lightest (255 value) points of our image and therefore, the wider the range expands, the more Contrast we see within the frame.  By reverse, images with narrow Tonal Ranges cover more restricted areas between the lightest and darkest values producing images with less Contrast.

Capturing a wide Tonal Range in both Black & White and coloured photography should be our main objective as this is a vital element of our photography and will make our photos far more interesting for the viewer.  However, it should be noted that we are only able to do this if the dynamic range on our camera’s sensor is capable of capturing a wide distribution of tones and we will look at this later.

Another element that could/should be taken into consideration when thinking about Tonal Range is the Zone System, which was devised by the landscape photographer Ansel Adams, and can be applied to obtain the correct exposure and difficult or tricky situations.  I have not written about this here, but details can be found at the following link:

http://photo.tutsplus.com/articles/theory/understanding-using-ansel-adams-zone-system/

Contrast

Tying in nicely with Tonal Range is Contrast, as the two go hand-in-hand as they each influence the look and feel of our photographs.

The dictionary states that Contrast can be:

“The degree of difference between tones in a television picture, photograph, or other image”.

“The state of being strikingly different from something else”.

“Enhancement of the apparent brightness or clarity of a design provided by the juxtaposition of different colours or textures”.

(The New Oxford American Dictionary)

Contrast is a way of emphasizing texture within an image and the more Contrast you include, the deeper the shadows will appear, with the hope of capturing something that jumps out of the screen.

We control the Contrast of photos in two ways, firstly by exposure and secondly by the cleaver use of lighting techniques.  To add Contrast to our images, we must add dark, or various degrees of darkness so that lighter areas are highlighted, and the darker areas are moody and mysterious, although these feelings are not always what we are looking to achieve, we are just looking for a more interesting photograph.

Contrast within photography can be explained in seven bullet points:

  • Contrast: The difference between dark and light
  • High Contrast: An extreme difference between dark and light
  • Low Contrast: A gradual or lesser difference between dark and light
  • Colour Contrast: Tonal differences, as well as saturation levels, of colours
  • High Key: Mostly light including whites
  • Low Key: Mostly darks including blacks

(SusanG n.d.)

Looking at this list, we can now get a grasp of how Tonal Range, Contrast and High/Low Key images tie in together.

Controlling Contrast in our images is managed by obtaining what we think is the ‘correct exposure’; then adding elements of black by stopping down between 1/3 to one full stop (or under exposing our image), which will assist in adding texture.  If shooting in manual (like I do), this is done by reducing your aperture to the narrowest setting that light will allow, then playing around with your shutter speed to make further dramatic changes.  If shooting in either Aperture or Shutter priorities, then the EV settings are the best way to underexpose your photos.

Dynamic Range

Finally, and as it really ties in with what is written above, lets look at Dynamic Range, and I must point out here that in my original post I seemed to merge two pieces of information into one as there are in fact two instances of Dynamic Range within photography, the first is within the scene we are looking to capture and the second instance happens within our camera.

The Dynamic Range of a Scene

When first looking at Dynamic Range, I used a quote from Freeman (2009 p. 38) were he mentions that “The Dynamic Range of a scene is the product of two things; the light falling onto a scene (its luminance) and the light reflected from the different surfaces within that scene (its reflectance), however, light is the most important element here.”

This makes sense, as the Dynamic Range within our scene will always be dependent on the available light we have to shoot with, which in turn effects the Tonal Range (0 through to 255), as well as the Contrast (under exposure) we are able to achieve within our image.

Although most literature dictates that there are two Dynamic Ranges, Low and High, according to Freeman, there could be as many as three, which are represented below:

Freeman's Idea surrounding Dynamic Range

Freeman’s Idea surrounding Dynamic Range

As photographers, we should be aware of this, as each scenario will have an impact on the photos we take AND the results we receive.

The Dynamic Range of Camera’s

As I have mentioned a few times now, so it should be sinking in; the Dynamic Range in photography is the difference in light between the darkest and lightest value, and as mentioned in segment on Tonal Range above, the human eye is very good at adjusting to the various values of light and is able to distinguish between shadows and highlights or darkness and light with ease.

In fact, the human eye can see 24 different stops of light, whereas our digital SLR camera’s sensor is limited to differentiating between only 12 different stops of light, and even less in smaller, more compact cameras, this is the Dynamic Range within our Camera.

Because of this differentiation, it is better to have a camera with the largest affordable sensor to you, as the sensor has the ability to collect a higher amount of light, due to the pixel size.  Getting technical for a minute, each pixel has a pit, which is called a photosite, and this photosite is used to measure photons.  Photons are little bundles of energy in which light travels, which in turn determine how bright or dark something is; so, the larger the photosite, the more photons it can measure, therefore more light becomes available…  (Eftaiha, 2011).

Unfortunately, data surrounding a Camera’s Dynamic Range is difficult to come by, so when conducting a photo shoot, it is always advisable to keep a close check of your histogram, as this will indicate whether the Dynamic Range of your image fits into the Dynamic Range of your Camera and as long as the reading from left to right is within comfortable limits, you know that you will have an average-to-low exposure, which can then be manipulated accordingly (Freeman, 2011 p.48).

To conclude:

I think now we can see more clearly how Dynamic Range, Tonal Range and Contrast all fit together to create more evenly exposed or more dramatically pleasing photos.  I wanted to conduct this exercise again, as I felt that I had previously rushed my research and my writings were not clear enough to understand fully.  I also wanted to do this as the coming exercise mentions all of these things and I wanted to make sure I got my facts right before taking my photos.

Source:

Reference:

Eftaiha, D.  (2011) Light & Photography: Exposure and Tonal Range Considerations [Online Article].  Available at: <http://photo.tutsplus.com/articles/theory/light-photography-exposure-and-tonal-range-considerations/&gt; [Accessed 5 February 2013].

Eftaiha, D.  (2011) Understanding & Using Ansel Adam’s Zone System [Online Article].  Available at: <http://photo.tutsplus.com/articles/theory/understanding-using-ansel-adams-zone-system/&gt; [Accessed 6 February 2013].

Freeman, M.  (2008) Mastering Digital Photography.  East Sussex: The Ilex Press Limited.

Freeman, M.  (2009) Perfect Exposure.  East Sussex: The Ilex Press Limited.

Freeman, M.  (2011) The Digital SLR Handbook.  East Sussex: Ilex Press Limited

SusanG.  (n.d.) Getting Better Contrast in your Photography [Online Article].  Available at: <http://digital-photography-school.com/getting-better-contrast-in-your-photography#author&gt; [Accessed 6 February 2013].

The New Oxford American Dictionary

Bibliography:

Callow, R.  (2009) Contrast in – Photography Composition Techniques [Online Article].  Available at: <http://www.brighthub.com/multimedia/photography/articles/954.aspx&gt; [Accessed 6 February 2013].

Cambridge in Colour.  (n.d.) Dynamic Range in Digital Photography [Online Article].  Available at: <http://www.cambridgeincolour.com/tutorials/dynamic-range.htm&gt; [Accessed 5 February 2013].

Freeman, M.  (2008) Mastering Digital Photography.  East Sussex: The Ilex Press Limited.

Freeman, M.  (2009) Perfect Exposure.  East Sussex: The Ilex Press Limited.

Freeman, M.  (2011) The Digital SLR Handbook.  East Sussex: Ilex Press Limited

Passman, R.  (n.d.) Dynamic Range and Contrast in Photography [Online Article].  Available at: <http://www.picturecorrect.com/tips/dynamic-range-and-contrast-in-photography/&gt; [Accessed 6 February 2013].

Rockwell, K.  (2008) Dynamic Range [Online Article].  Available at: <http://www.kenrockwell.com/tech/dynamic-range.htm&gt; [Accessed 5 February 2013].

Sheppard, R.  (2008) Expanding Photography’s Tonal Range [Online Article].  Available at: <http://www.outdoorphotographer.com/columns/digital-horizons/expanding-photographys-tonal-range.html&gt; [Accessed 5 February 2013].

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