As I covered in Part 1, ISO is an important setting when it comes to proper exposure, especially in low light situations. Unless you’ve manually changed it, when you’re in Auto mode, the camera controls the ISO setting. In my previous post I suggested that you manually set this setting yourself for better results. This can be a blessing and a curse especially if you forget to change your ISO from one session to another or if you go from one lighting situation to another like using a high ISO when shooting indoors and then go outside to a bright sunny situation.
I recently discovered a little known feature that gives you greater control over ISO while in Auto ISO mode. Most cameras allow you to set parameters for getting greater control over Auto ISO. I shoot Nikon and this setting is called the “ISO sensitivity settings“. Its the same menu that allows you to change your ISO mode from Auto to manual and change your ISO setting using the menu rather than the controls on the back of the camera. When you to this menu set “ISO Sensitivity Auto Control” to ON (this turns on Auto ISO) and then adjust the maximum sensitivity setting to the highest ISO setting your camera you’re comfortable shooting. For me, on my Nikon D90, that would be 1600. On my D600 I would set it to 2500 without any issues.
The next setting to adjust is the “Minimum shutter speed”. This is the slowest shutter speed you want to shoot at before it ups the ISO. I set mine to 1/100. What that tells the camera is that “If the shutter speed hits 1/100 up the ISO to get the correct exposure.” So if I’m in Auto mode in a low light situation, my camera will automatically increase the ISO if the shutter speed decreases to 1/100. This setting works in any of the semi-automatic modes as well as Manual mode. It’s a great crutch as you’re learning to shoot in Manual. By enabling this setting in this mode, you’re able to have the camera control ISO and while you worry about the relationship between Aperture and Shutter speed.