Here’s a quick, foolproof way to correctly set shutter speed and aperture values for manual exposures.
When your camera is in manual mode you’ve disabled its ability to set shutter speed and aperture values for you. However, the camera’s meter is still active, and as long as flash is not involved, you can still use this sophisticated metering system to help you choose the correct values.
I recently helped a coaching client set up a small studio to photograph still life compositions. To keep lighting setups simple, she will be using continuous light—not flash.
Photo 1 shows the basic setup. We will be using a single compact fluorescent light fixture with a 42” white shoot-through umbrella at camera left as a key light, and a silver reflector at camera right for fill.
Once our subject is in place (in this case an orchid) and the key light and reflector are positioned the way we want, it’s time to select an aperture and shutter speed combination that will give us a correct exposure.
The question you may be asking right now is, “Why use manual mode at all, why not use aperture or shutter priority?”
The answer is you could, but you will be relying on the camera to set the correct exposure in what is a typical situation where the camera’s reflective meter will likely be fooled. If you want to know why, take a look at my blog post, Metering 101.
In a still life composition, depth of field is much more important than shutter speed. We will begin by selecting an aperture of f/16, which should provide the desired depth of field.
Now let’s use the camera’s meter to select a shutter speed, but let’s make sure the meter gets it right. We’ll do this by metering off of a value known to the camera—a value that will not fool the meter—18% gray.
Photo 2 shows an 18% Gray Card standing in for our subject on the posing table. Now it’s time to “Zero” the camera’s meter.
- First, make sure all the camera sees is the gray card. Either zoom in or move the camera closer so that all you see through the viewfinder is the gray card.
- Next, depress your shutter release part way so that your meter is active.
- Now check your camera’s exposure level indicator. This is the same plus/minus scale you use to set exposure compensation in Shutter and Aperture Priority Modes. Most cameras will display the indicator in two places; on the LCD info screen (see Photo 3), and in the viewfinder.
- As displayed in Photo 3, note that at a shutter speed of 1-second at f/16 the indicator hash mark registers at Minus 1. The meter is telling us we are one stop underexposed.
- Last, “Zero” the meter by changing the shutter speed setting until the index hash mark is registered dead center at the “Zero.” (Note: if the indicator disappears, tap the shutter release button to activate the meter again.) As you can see in Photo 4 by changing the shutter speed to two seconds the hash mark now registers at zero, indicating a correct exposure.
Once you have done this a time or two you’ll see how easy it is to set a correct exposure using a gray card in manual mode.
From a studio still life composition, to a natural light portrait, I use this method whenever I am photographing a subject illuminated by a continuous light source.
Give it a try!
Until next time,