The option for AF Microadjustment is found in the menu under the [AF 5] tab:

Select the AF Microadjustment option, then press SET on the camera.

For FoCal, the adjustment will be per-lens, so select Adjust by lens, then hit the INFO button.

Single focal length (prime) lens:

For a prime lens, you can adjust the value on the screen then hit SET.

Zoom lens:

For a zoom lens, select W (wide-angle) or T (telephoto) as instructed by FoCal, then hit SET.

Adjust the value using the rear dial, then hit SET to save the chosen value.

Hit the MENU button to return to the previous screen. You should see your chosen values selected:

Although FoCal can control the Canon EOS-1D X Mark III to adjust almost all the necessary settings for testing, the camera does not allow adjustment of the AF Microadjustment setting over USB.

During Automatic Calibration or MultiTest, you may be requested by FoCal to change the AF Microadjustment a few times, e.g.:

While this message is shown on the screen, the camera controls will be enabled and you can change the AF Microadjustment setting on the camera.

By default, Voice Prompts will be enabled, meaning your computer will speak out the change you need. Combined with the Camera Hotkey (see below), this makes changing the AF Microadjustment option very quick and easy.

Quick Change

It's actually really quick to change the setting on the camera after the first time, as the menu options will be selected from any previous changes.

On Canon cameras, the sequence is:

• MENU: opens the menu
• SET: selects AF Microadjustment
• INFO: selects Change to allow editing
• Adjust the value on the screen, then hit SET to accept
• Action the hotkey as shown below to continue.

Camera Hotkey

In order to make the change of AF Microadjustment as painless as possible, you can use the camera hotkey feature of FoCal to signal that you have made the necessary change.

Once the change is made on the camera, to use the hotkey, simply:

• Half-press the camera shutter button to return to shooting mode
• Click the appropriate dial by one position to change the aperture or shutter speed

This change in aperture/shutter speed will signal to FoCal that you have made the change. After a short delay to allow the camera to settle, FoCal will take control again, restore the aperture/shutter speed for the test and continue.

Choose a location with a solid floor

Ground floor locations are less likely to vibrate when people move, trucks drive past outside the building etc. The quality of your test results will be affected if there is vibration to the camera/lens during the test.

Attach the target firmly to a vertical wall at approximately the height of the camera lens

If you print the target yourself, make sure it is flat and cannot blow around during testing. We recommend using a FoCal Hard Target (available from the Reikan FoCal Store) as these are the targets we use for all our development and testing.

Ensure the target is well lit with a stable light source

We don’t recommend the use of fluorescent or LED lighting as they can flicker – you won’t be able to see this with your eye, but the camera can be affected and the results may not be as accurate as possible. Also avoid changeable outdoor lighting - e.g. clouds moving across the sky. FoCal can compensate for small light level changes, but large changes can cause problems during testing.

Attach the camera or lens to a solid, sturdy tripod

If the option is available for your tripod, you can hang something heavy from the hook at the base of the centre column to further stabilise the camera lens during testing.

For large lenses, use the supplied tripod collar and attach the lens to the tripod (not the camera) - this will not only reduce strain on the camera mount, but also make the whole camera/lens system more stable.

Position the camera the appropriate distance from the target

The Target Distance Tool in FoCal will guide you. You can use this either with or without the camera connected to FoCal. More information is available at help.reikanfocal.com/targetdistance.

Connect the camera to the computer

You will require a USB cable with a USB-C connector to connect to your Canon EOS-1D X Mark III.

Use the USB cable supplied with your camera or a high-quality alternative, and avoid extension cables. Low quality USB cables can cause considerable unreliability during testing and it's usually the first thing we suggest changing if you get unreliable operation of FoCal!

Check the camera battery is at least half (>50%) charged

Low batteries can cause the tests to run incorrectly or to fail. FoCal can catch and properly identify most issues, but if a battery is low or exhausted the camera may behave unexpectedly and you may see strange behavior.

Remove any battery grip from the camera

Battery grips can cause considerable extra vibration when mounted on a tripod - remove them before you calibrate.

Aim the centre focus point of the camera approximately at the centre of the FoCal Target

You don't have to be too precise - positioning will be confirmed during Target Setup.

Cover the eyepiece of the camera (DSLR Only)

This stops stray light entering the back of the camera and affecting exposure during tests.

Further general information on Network connection - specifically related to both Hotspot ('Easy') and Infrastructure modes - is available on the Camera Network help pages.

Important: You must ensure the WiFi option for Canon is enabled in the software settings, otherwise the camera will not be detected by FoCal.

For instructions on how to use WiFi with the Canon EOS-1D X Mark III, please see here.

Switch to Photo mode

The Canon EOS-1D X Mark III can operate in both Photo and Video mode. If there is a selector switch, ensure that it is switched to Photo mode.

Disable WiFi

The WiFi feature on the Canon EOS-1D X Mark III can interfere with communications with FoCal over USB, so please ensure that WiFi is disabled.

Remove any mode limits

Some cameras allow you to limit available options for various settings. If this is possible on your camera, please ensure that the following are allowed options:

• AE Mode: Aperture Priority and Manual
• Metering Mode: Spot Metering, Matrix/Evaluative Metering
• Aperture: All apertures
• Shutter Speed: All shutter speeds
• ISO: All ISO values

Switch to Aperture Priority Mode

Most tests in FoCal use Aperture Priority mode, so it's a good idea to switch to this mode when you start.

If a tool in FoCal requires a different mode, you will be asked to change.

Select non-continuous Autofocus mode

Ensure the autofocus mode of your Canon EOS-1D X Mark III is set to One Shot.

To check, when you half-press the shutter button, the camera should lock focus (with a beep if this is enabled), and then stop focusing.

Select single focus point mode

You should not use any automatic focus point selection modes. When you look through the viewfinder and activate autofocus (half-press the shutter button or use the AF-ON button), you should see only a single, non-moving AF point selected.

Choose the Centre focus point

Most FoCal tests require use of just the centre focus point, so set that single point (from the step above) to the centre.

Ensure Focus Limiter is disabled on lens (if applicable)

FoCal may use the whole of the lens focus range during testing. You may encounter errors if the range of focus is limited on the lens, so make sure the limiter is set to OFF or the minimum-to-maximum range (note this option is not present on all lenses - it's usually available on longer telephoto lenses or macro lenses).

Ensure any image stabilisation is disabled on lens and/or in-camera (if applicable)

You should disable any image-stabilisation option on your lens, as it can reduce the quality of the results.