Lens calibration and Focus

Studio Operators Content Creation Post Effects Camera Tracking

 

How can one calibrate lenses for different focus positions?

Focus shifts can cause focus breathing/shifts, but it seems like the lens calibration tool always assumes to have the chart 100% in focus. It seems to not consider the focus encoder values from the tracking system.

Or is there a way to change the calibration to also calibrate for different focus encoder values? It seems to ignore the lens focus data.

   jim4586

 
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Eifert@Aximmetry
5/26/2022 11:19:39 AM
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Hi,

The calibration should be done with one focus setting. You should not change the focus while calibrating the lens or the tracking.
So before starting the calibration process, it is recommended to set a focus that will have the calibration board in focus throughout the calibration process.

There is no way currently to calibrate with different focus encoder values. This might change in the future.

Warmest regards,

 
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jim4586
5/26/2022 11:59:59 AM
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I understand but you are not considering focus at all, which means the whole illusion can break when the camera operator needs to change focus to keep the actor sharp. 

When the actor stands at a different camera distance than the calibration chart used to be, the calibration is then off with most lenses since the focus distance needs to be different to keep the actor in focus.

You are not compensating for any spherical focus breathing or anamorphic focus breathing that could occur. But even the highest-end lenses breath ever so slightly. This becomes obvious when doing focus racks.

The current approach of lens calibration makes it very difficult to use in a real-world production…

 
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TwentyStudios
5/26/2022 6:49:08 PM
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@Eifert: This is very concerning and disappointing. Any professional camera calibration NEEDS to take different focus distances into account. It’s frankly unbelievable that you haven’t considered this with the new calibration workflow. 

 
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Eifert@Aximmetry
5/27/2022 12:22:13 PM
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Hi,

Aximmetry plans to continuously improve the Camera Calibrator. And we have focus inclusive calibration process in our implementation list.

Warmest regards,