Push versus flash
Written by Bill Hankins
Knowing how to get the best images in any quality of light.
The more things change, the more they remain the same. Digital photography reminds us of that adage. When it comes to young photojournalists deciding whether to use a flash, the problems and solutions are much the same as in the days of film. Today’s digital cameras offer some ease that we did not have in the film days, but choices must still be made. This Photo Quest should help budding photojournalists make better choices in getting the best images for their yearbooks.
First, digital cameras allow ease in flash use, since many brands of SLRs have a pop-up flash for use in low-light situations. Even with a hot shoe for attaching more sophisticated flashes, this pop-up option is nice to have and works well in many situations.
Also, digital cameras give photographers a choice of image sensitivity, what we used to call film speed. In the old days – 10 or 12 years ago – we could choose film speeds based on our needs: slow film with fine grain (100-200 ISO) for good lighting situations, medium film with a bit coarser grain (400 ISO) for a variety of situations, and high speed coarse grain film (3200 ISO) for really low light and sports shooting situations.
Before Kodak brought out its 3200-speed film, we would often push our film (Tri-X or T-Max 400) from the 400 speed to 800, 1200 or 1600. This would underexpose the film by allowing a faster shutter speed, fooling the camera’s light meter into the idea of a more sensitive film being used in the camera. Through special processing of the film, the underexposed image could be coaxed out with a slight, or more so, grainy effect.
Today, digital SLRs will allow a shooter to change sensitivity from one frame to the next. For example, if shooting a soccer match on an overcast day, you might set the ISO on 400, but soon the clouds thicken, the sky grows dark and instead of shooting at 1/1000 of a second you are down to 1/250. You can simply change your ISO setting from 400 to 1600 – something you could not do in the middle of a roll of film – and you are back to shooting at 1/1000. Of course, there is a trade-off. Instead of increased grain as with pushed film, you will have a bit more digital noise.
For shooters who did not know how to push film and process it accordingly, flash use was the usual alternative. Flash use presented its own problems with film that we still face today. The flash does not allow the photographer to blend into the situation, such as a classroom. When the flash goes off, people tend to notice the photographer. The flash can announce its presence in a photograph as well by leaving a shadow behind the subject or a hot spot. Composing an image, by framing a subject or using leading lines or other arrangement to help communicate the story better, becomes more difficult with an on-camera pop-up flash.
Following are some examples that will help illustrate the choices a photographer should consider when trying to shoot when the light source is not the most conducive for quality photojournalism.
Pushed ISO – 1600
Here is a nice moment captured by a yearbook photographer at Oak Park High School in Kansas City, Mo. The low light forced the shooter to move the sensitivity rating to a fairly high 1600 in order to shoot at a shutter speed that allowed the camera to be hand-held and for the subjects to be sharp.
The downside: If you enlarge this image, digital noise will be more noticeable than if the ISO were set at 400 or lower. Some photographers, who accepted the documentary quality of film grain, cannot tolerate heightened digital noise.
Pop-up flash used – ISO 800
This image also shows some nice interaction during a school blood drive. The basic subjects are well exposed. With the use of the flash, I am not sure why the photographer kept the ISO at 800. Probably 400 or even 200 would have worked OK with the flash.
The downside: Notice the hot spot behind the subject on the wall mat. Also, the white machinery and the items in the foreground caught the light of the flash and are much too bright, distracting from the main subjects. All of these things announce the presence of a photographer.
Pop-up flash used – ISO 400
Pop-up flash use can be a problem when using a wide-angle lens, at least when you normally have a lens hood on your lens as I do. To illustrate, I shot Scott McInnis going over plans with a student with a 20mm lens to help show some of the environment of McInnis’ wood shop classroom at North Platte High School in Dearborn, Mo.
The downside: Ouch! That big shadow in the foreground is the top edge of my lens hood. Luckily, with digital you can see such errors and correct them, in this case by removing the lens hood while shooting wide-angle.
Problems with composition
Framing your subject
Pop-up flash use can be a problem here because the framing elements catch the light and often cast a shadow on your main subject. Pushing the ISO to 1200 (below, right) allows a suitable shutter speed and clean framing, but adds some digital noise to the image.
Playing with depth of field
When using an on-camera pop-up flash, it is harder to control your depth of field. Sometimes you want the area behind your main subject to add to the message of the photo while not allowing the background to intrude too much on the subject. For example, notice in the flash image (below left) that the background is measurably sharper than the “pushed” image (below right), which was shot at ISO 1200. Because of the flash use in the photo, the lens had to be stopped down to f/5.6 to not overexpose the main subject. F/5.6 gave more depth of field than the f/2.8 in the right photo.
Depth of field includes the areas in front of and behind your subject that are also in acceptable focus. The f/stop is one of the controls that most affects depth of field. The others are lens length and your distance from your subject
Think about how you might use this control of depth of field to your advantage.
Pushing your ISO to 1000, 1200 or 1600 in lower light situations can help you shoot at an acceptably fast shutter speed AND control your depth of field with your f/stops more than you can with a built-in flash. The added noise is often a fair trade-off.
Freezing the motion
When flash is your friend
As you can probably tell, in most situations I prefer to bump up that ISO to get the shot I need. That flexibility is one of the beauties of digital cameras over film. We are not bound by the physical and chemical limitations of film. However, there are plenty of situations when a flash is your friend. For example, in the situation on the left, pushing the ISO to 1200 helped get the close-up image of using a table saw with the blade whirring and sawdust flying. On the bottom right, the flash has frozen the moment, showing the sawdust distinctly above the saw. This photo has a different feel to it and a different impact. Which is better is your choice as you edit your own images. But the point is that photographers should be aware of the benefits and limitations of their equipment and be ready to use the best technique for a given situation.
If you need to be subtle in your shooting and quietly blend in with your environment, then push your ISO. You will have more flexibility with your composition and not have to worry about flash hot spots or reflections. However, if you plan on using your image large on the page, noise becomes a consideration, so maybe a flash and low ISO is the best. A smart shooter will make sure that the composition will still be interesting and will move around so that there will be no distracting hot spots or shadows.