ISO setting technology in digital cameras replicates the rated speeds of old-fashioned film. In very general terms, ISO is the light sensitivity of the sensor in the same way that film sensitivities were more or less sensitive to light. But there are differences between film and digital sensors; specifically, as the sensitivity setting on a digital camera is increased, the output of the sensor is also amplified. This was called grain when we were using high speed film. So while you have the option to increase ISO sensitivity at any point in the shot, the trade-off for increased amplification or the build-up of excessive pixel load is increased digital noise. And the result of digital noise is an overall loss of resolution and image quality.

In part because the 5D Mark II has relatively large pixels on the sensor and because Canon has done a good job of implementing advanced internal noise reduction processing, the 5D Mark II comes out on top even at high sensitivity settings, particularly at the exhibition. times of 30 seconds or less.

In this smart mode taken from point-and-shoot, Auto ISO controls your sensor’s sensitivity based on what shooting mode you’re in. In Full or Creative Auto, P, Tv, or Av, the camera selects from an ISO range of 100-3200. Switch to M, B or add a Speedlite and Auto ISO will lock at 400. Auto ISO displays as A on the LCD panel when selected and is located at the bottom of the scale by turning the main dial counterclockwise. clockwise after pressing the ISO Select Button button.

ISO Range and Custom Feature Options

The 5D Mark II offers a wide ISO range, including Auto and settings from 100 to 6400 in 1/3-stop increments or 1/2-stop increments, set via the options in C.Fn I-01. The ISO range can be expanded to include ISO 50 (displayed as L), 12800 (displayed as H1), and an incredible 25600 (displayed as H2) by setting C.Fn I-03 to On. Note that ISO 50 reduces the dynamic range in highlights by about 1 stop, making this sensitivity less useful in high-contrast lighting. ISO 50 can be useful in a studio environment by providing flexibility in the choice of aperture.

With the 5D Mark II, Canon offers an option to reduce or eliminate noise in long exposures.

With the Long Exposure Noise Reduction option, available when using C.Fn II-01, noise is completely or nearly eliminated by in-camera processing which is very capable but takes almost as long as the exposure to complete.

ISO and extended range ISO settings

To change the ISO setting on the 5D Mark II, follow these steps:

1. Press the ISO selection button on the LCD panel. The current ISO setting appears on the LCD panel and in the viewfinder.

2. Turn the Quick Control dial clockwise to set a higher sensitivity or counterclockwise to set a lower sensitivity. The camera displays the ISO setting as you turn the dial. If you have ISO expansion enabled using C.Fn II-01, ISO 50 is displayed as L, ISO 12800 is displayed as H1, and 25600 is displayed as H2. The ISO option you select will remain in effect until you change it again.

To activate ISO expansion, follow these steps:

1. Press the Menu button and then tilt the multicontroller until the Custom Function menu (orange) appears.

2. Click the Configure button. The Custom Function screen appears and the Custom Function number control in the upper right corner of the screen becomes active.

3. Rotate the Quick Control dial to set the C.Fn I number to 03, and then press the Set button. ISO expansion control is on.

4. Turn the Quick Control dial clockwise to select option 1: On, and then press the Set button. ISO expansion stays on until you change it.