When it introduced its first mirrorless full-frame camera, the Canon EOS R, Canon also snuck out a new exposure mode. This isn’t immediately obvious as the mode dial has changed from the ones used on Canon DSLRs. But if you press the Mode button on the top-plate, and rotate its surrounding dial, you’ll spot Fv amongst the usual P, Tv, Av and M options.
Fv stands for Flexible value. It sets the camera to Flexible Priority Auto Exposure mode. It’s flexible because it allows you to swap between program, aperture priority, shutter priority and manual mode. It also gives you convenient control over sensitivity (ISO) and exposure compensation.
Just to be clear, I’ll explain the differences between program, aperture priority, shutter priority and manual mode.
Program Mode (P)
In program mode, the camera takes control of the shutter speed and aperture settings. The camera sets the values that it calculates give the correct exposure when the shutter button is pressed half-way. You can see the aperture and shutter speed it has set in the viewfinder and on the main screen.
If you want to use a different aperture or shutter speed, it’s just a case of pressing the shutter button half-way and then rotating the main dial near the shutter button. Rotate the dial until you get the setting you want. The camera maintains the same exposure, but it’s achieved with a different shutter speed and aperture combination.
If the camera makes the image to light or too dark, you can use the exposure compensation control to correct it before taking another shot. However, the EOS R can show you how the image will look before you take the shot. As a result, you can get the exposure just right before pressing the shutter button to take the shot.
Shutter Priority (Tv)
Canon calls shutter priority mode, Time value or Tv mode. When this is selected, you set the shutter speed while the camera takes care of the aperture. It’s a great mode to use when you want to ensure that movement is frozen or blurred.
As with program mode, you can use exposure compensation to adjust the exposure of your image.
Aperture Priority (Av)
In aperture priority or aperture value mode as Canon likes to call it, you set the aperture while the camera sets the shutter speed automatically. This is a useful mode when depth of field control is the most important consideration. It’s handy for portraits for example. You can set a wide aperture and shoot away as the light changes, not having to worry about changing the shutter speed.
Again, you can use exposure compensation to adjust the brightness of your image before taking the shot.
Manual Exposure Mode
In manual exposure mode, you set both the shutter speed and the aperture. It means you are in complete control of the exposure. The camera displays an exposure guide to let you know if it thinks the image will be dark or light. But you can ignore it and set whatever values you want.
Manual exposure mode is useful in tricky lighting conditions or when your subject is exceptionally light or dark. If you let the camera take control of exposure when you’re photographing a black cat, for example, the cat is likely to look grey in the image. You get select exposure settings that the camera thinks will underexpose the image but will, in fact, deliver a correct result.
If the sensitivity (IOS) control is set to automatic, you can use exposure compensation to darken or brighten the image.
Flexible Priority (FV) Mode
When Flexible priority mode is selected, you can choose to control any or none of the exposure parameters. In addition to shutter speed and aperture, it gives you the option to control sensitivity (ISO) and exposure compensation.
When Fv is selected, use the Quick Control Dial around the mode button to select one of the four exposure parameters. Then use the main dial to adjust the value to the one you want.
You can set the sensitivity to automatic or a specific value in aperture priority, shutter priority and manual mode. That mean that Fv isn’t really a new exposure mode so much as a new way to select Av, Tv and M mode and the exposure settings.