Target Distance Tool

Having the right distance between the camera and the FoCal Calibration Target is important in getting accurate and useful calibration results. FoCal’s interactive Target Distance Tool lets you check the required distance for calibration quickly and easily.

Opening the Target Distance Tool

Choose Tools > Target Distance Tool from the main FoCal window, or hit CTRL+G to open the Target Distance Tool.

Using the Target Distance Tool

The Target Distance Tool operates in 2 modes.

Interactive Mode (No Camera Connected)

With no camera connected, you can choose any focal length using the slider (next to the Specify focal length text). Moving this slider will update the minimum target distance displayed at the bottom of the window. In the example above, for a focal length of 24mm, we require a minimum target distance of 1.2m.

With Camera Connected

With a camera connected, the Get focal length from attached camera will be automatically selected when the tool is opened and the bottom of the window will display the appropriate distance for testing with the attached lens. If there is a zoom lens attached to the camera, you will see the distance for both the Wide and Telephoto ends of the range.

You can choose the Specify focal length option if you wish to run in interactive mode and try out different focal lengths, even with a camera attached.

Further Information

Note that the crop factor of the camera is not relevant in determining the target distance requirement for calibration, so the distance is the same whether you are calibrating a full-frame or cropped sensor camera.