Capturing black-and-white images (Part 1 of 3: Understanding exposure)

Great photography is about depth of feeling, not depth of field.”
Peter Adams

This post, and the next two are part of a series in which I’m addressing the topic of black-and-white. In the two first posts I provided an overview of what black-and-photography is about, in the third one I started a discussion on visualizing black-and-white images. So, in the next three ones I’ll provide some advice in order to start shooting images with the idea of converting them to black-and-white.

This series will include posts and videos that can be easily located by using the tag “learning-black-and-white” either in the search box above, or by directly clicking on the tag name at the bottom of this post.

This topic will be broken down in three different posts corresponding to the three aspects that I recommend to keep in mind when shooting black-and-white image:

  • Understanding exposure
  • Using filters to improve image quality, and
  • Shooting RAW images.

The first aspect mentioned above really applies to photography in general, whereas the last two even though also apply to photography in general, in black-and-white photography are particularly relevant,  we’ll see why during the development of the rest of the topic. Let’s get started with the first aspect.

Understanding exposure.

Regardless the type of photography you do, getting a good exposure in-camera is a must in order to get good quality images to convert to black-and-white. In very simple terms, exposure is a combination of three metrics: Aperture, Shutter Speed, and ISO. So, first of all let’s take a look to a basic definition of each of these metrics:

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Figure 1. Americana © Enrique Peláez

Aperture: It controls the lens’ diaphragm, which opens or closes in order to control the amount of light going through the lens. Usually the lens aperture is measured in f-stops, going typically from f/1.2, f/1.4, etc all the way to f/22 and more depending on the type of lens. The higher the number, the closer the diaphragm, which results in a larger image Depth of Field (DoF). So, the lens aperture controls the DoF of the image, which according to Wikipedia “is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.  In some cases, it may be desirable to have the entire image sharp, and a large DoF is appropriate. In other cases, a small DoF may be more effective, emphasizing the subject while de-emphasizing the foreground and background.

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Figure 2. Melancholy © Enrique Peláez

Figure 1 is an example of using an small aperture in order to get all the image in focus (sharp). This image was shot at f/25, 1/80 sec, ISO 320. Using an aperture bigger than f/25 would probably get some of the areas in the foreground or background out of focus.  Now, take a look to figure 2, this image was shot with a big lens aperture (f/1.4, 1/500 sec, ISO 200), so clearly the background is de-emphasized by using a very narrow DoF in order to focus the viewer’s attention on the subject, in this case the leaf.

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Figure 3. I wanted to fly © Enrique Peláez

 

Shutter Speed: It’s the speed in which the shutter opens then closes, determining this way the time the digital sensor inside the camera is exposed to light. Usually shutter speed is measured in fractions of a second ½ sec, ¼ sec, ⅛ sec, etc all the way up to 1/4000 and more depending on the characteristics of your camera longer exposures all the way up to hours, are totally possible depending the kind of camera you have, I´ll talk more about this topic when we cover long exposure photography as part of this series.  Shutter speed controls the image motion. In simple terms, if the shutter speeds is equal or greater than the speed of the moving object, this will be recorded tack sharp, otherwise a blur will appear.  Figure 3 is an example of using a fast shutter speed in order to freeze the action in the image, this image was shot at 1/200 sec, f/4, ISO 640.

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Figure 4. In the blood © Enrique Peláez

ISO: In film, ISO indicated how sensitive a film was to light, whereas in digital photography ISO is an arbitrary measure of the relationship between exposure and the sensor data values that determines the amplification of the signal on the sensor in order to mimic film sensitivity. In real film photography high ISO values produced a bigger grain, whereas in digital photography higher ISO values produce noise.  Now, the advantage of the digital approach is that much higher ISO values than in film can be achieved, and thanks to in-camera and post-processing technologies, noise can be highly reduced. Nevertheless, in general terms the safest ISO values for digital cameras today regardless of the manufacturer are between 100 and 400. At more than 400 you will start getting some noticeable noise in your images. Figure 4 is an example of using a high ISO value to capture an image. Given the low light conditions in circuses a high ISO value had to be used to shot this image (ISO 1250, 1/500 sec, f/9). Thanks to the use of different techniques in post-processing to eliminate noise, this image can easily be printed in a large format, in subsequent posts in this series I’ll address some techniques you can use to get rid of noise but again, in my book, high ISO values must be used just as a last option. 

As you may already know, these three metrics are obviously interconnected, most photographers and educators have tried for years to represent the interaction among the three into the context of the “mythical” exposure triangle, but don’t get obsessed on the “triangle” representation, actually it’s a triangle only because there are three aspects to control, but the interaction among the three of them has nothing to do neither with a triangle side proportion nor vertex proportion. We’ll get back to this topic in another post later in this series, but for now it’s enough to remember the following three aspects before you go ahead and start practicing using different combinations of these three variables by yourself, which in my opinion is the best approach to grab the way these three variables work together. So, here you go:

  • The more available light, the the smaller aperture you can use. Remember, every stop value is a fraction number so, for example f/22 is smaller than f/1.2.  The smaller aperture, the larger DoF.
  • The more available light, the faster shutter speed you can get. The faster shutter speed, the sharper moving subjects you’ll capture. Remember you are measuring the time the sensor is exposed to light, so 1/1000 sec. means a faster shutter speed than 1/500 sec.
  • The more available light, the lower ISO you can use, and in this way you can get good quality images!  Remember ISOs values higher than 400 will get noisy images.  

As I said, as part of this series I’ll publish more specific posts regarding exposure that hopefully will help you to reinforce the concept, but for now all you need to know in order to start practicing, and make sense by yourself  how to play with these three exposure variables (aperture, shutter speed, and ISO) is here. So, go ahead and practice, and let me know how it goes.

In the next post I’ll start discussing using filters to improve your in-camera captures and after that, we’ll close this topic discussing why it’s so important to shoot RAW. So, keep in touch.

I do appreciate your comments and suggestions. If you are interested in more information regarding the making of my images, as well as general information about black-and-white photography, please subscribe to my blog to receive automatic notifications every time I publish a new post.

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