I am using a Sigma f/2.8 120-300mm lens. How does the C1 and C2 affect pictures? Also, what about the Off, 1, and 2 switch on the OS feature?


Many cameras have 'C1', 'C2', etc. settings that allow the user to save a "preset" combination of specific settings that can be available at the flick of the mode dial.

Sigma's "Global Vision" series of lenses is similar. Many of them allow customization of things such as Optical Image Stabilization, Autofocus Speed, and Focus Limiter range. When the switch is set to 'Off' the factory defaults are applied to these parameters. The customized settings can be accessed by sliding the switch to the desired position. You can have one customization profile for 'C1' and a different customized profile for 'C2'.

To set up a 'Custom Setting', you need to connect the lens to a computer running Sigma Optimization Pro via the Sigma USB Dock. The USB dock only works with Sigma's 'Global Vision' lenses: the Art, Sports, and Contemporary series. Other Sigma lenses are not compatible with the USB dock.

You can download the basic instructions for the Sigma 120-300mm f/2.8 Sports DG APO OS HSM.

You can also download the Instruction Manual for Sigma Optimization Pro.
There's a multi-video tutorial on how to use SOP.

There's a good bit about the customization options and how to use them at this review of the Sigma USB Dock from The-Digital-Picture. He also discusses the AF speed customization at the review of the Sigma 120-300mm f/2.8 Sports lens.

The switch on the lens marked 'OS' controls the lens' optical image stabilization feature.

  • 'Off' turns OS off
  • '1' turns OS on in both the up/down and left/right directions
  • '2' turns OS on in 'panning' mode. The lens will detect which direction the lens is being panned at a steady rate and only provide stabilization on the axis perpendicular to that motion. If you are holding the camera in landscape orientation and panning from left to right, the OS will only attempt to correct for up and down movements of the lens in order to allow you panning motion during the exposure to be smooth instead of choppy due to the OS fighting your panning movements.

This Sigma lens allows you to make and store two custom user settings. Once programmed you can select which one is in effect i.e. C1 or C2 via a switch. Additionally you can turn “off” these presets.

Programing this lens requires Sigma software for your computer and a specialized USB cabling. You can find out more if you read the manual that accompanies this lens.

You can select and program the motor speed of autofocus “AF Speed Settings”.

You can set limits over the span of the distance of the AF distance range “Focus Limiter Setting”.

You can set considerations as to how the optical stabilization operates “OS Settings”

  • interesting. I did not purchase this lense. I am only renting it, therefore any instructions did not come with the lense – Randy Coffman May 5 '18 at 19:05

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