Summary
Sometimes you might need to trim your lenses to make sure they are not forward or backwards focusing. The different methods can be found below.
In-Depth
An Auto Focus trim is a calibration to fix front or rear focus issues.
With Feature Update # 4 for the XF Camera System, we implemented a dedicated Focus Trim Tool. It is disabled from the swipe sequence by default, but can be enabled by the user. It can also be reached from the Tools menu, but it is not possible to assign an Icon control to this tool. It is considered a tool that should not be used in everyday work, but only when the system needs calibration. The tool works in a step by step workflow, that makes it easy to do a focus trim:
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Initialize
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Adjust Focus
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Measure focus trim
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Save and verify
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Done
It is important that the physical setup is correct to ensure a proper focus trimming. Particularly the light conditions are important. The target should be a target suitable for focusing, and roughly a little closer than the middle focus distance. The settings should be:
It is highly recommended to use Capture One in tethered mode to get the best possible way of checking focus.
When the Focus Trim tool is entered, it first need to be started (initialized). The initialization process in initiated by Start Tool. The first screen will also show what lens is present. If no lens can be detected, the text will be empty.
When the tool is started, it runs through an initialization process, which involves:
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Verifying that the lens has auto focus capabilities
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Verify that the target is at a proper distance, not too near, not too far
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Verify that we can do an auto focus on the target
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Verify the amount of light
If the tool detects any issues, it displays a dialog with status:
Light and Target problems does not prevent to continue with the Focus Trim tool, but it is highly recommended to fix the issue and start all over. Hit the "X" in the top left corner to continue.
Next step is to adjust focus manually so it is as sharp as possible. This is done by jumping into Live View to confirm the focus adjustments. Again, it is highly recommended to use Capture One's live view for this:
*Note that if LiveView is entered either locally on IQ, or on Capture One will be indicated on the screen. If the Live View is on Capture One, the Live View icon will dissapear, because it is not possible to exit Live View on Capture One from the IQ, therefore, exit Live View in Capture One.
Once perfect focus has been found, the XF is ready to calculate the new Focus Trim value. Make sure that the XF has exited LiveView, so the Auto Focus system can work.
The Auto Focus system now makes a series of measurements and if it can reliably detect focus, it shows the progress bar in green, and displays the next step, where the new focus trim value can be stored. If the mea- surement fails, the progress bar will turn red. The more it is filled, the more convincing measurements. Bad measurement could be due to too much variance in the measurements caused by low light or a bad target.
Once the focus trim value has been saved, you can verify by capturing a couple if images with the new value using the Capture button (rear button):
Manual Trim Process