Hi,

It appears the issue may not be related to focus. Rather, it seems to involve zoom points where there's a minimal difference of only 0.001 (128.140-128.139) in zoom tracking, while the Focal Length has a difference of 0.6 (8.385-7.785):

Aximmetry will need to smoothly interpolate the 0.6 value into such a small difference, which is likely causing the jitter.

Warmest regards,

Hi, Eifert,  First of all, thanks for your advice.

Usually I would select a zoom value, change the focus, calibrate the FOV at intervals of 3 to 6 points, and so on, select multiple zoom values, and repeat. in the picture you marked ,that would be a mistake because the two value should be the same in my way. 

I just a litter confused , as you said, Aximmetry will need to smoothly interpolate the 0.6,  can i choose the same zoom value but different focus value for multiple points  calibration?

Best regards,

Dan

Hi Dan,

Yes, you can choose the same zoom value but different focus values for multiple points in the calibration.

Just make sure that the focus calibration points at a given zoom level share the exact same zoom value. This applies to both the Sensor's Zoom and the Focal length values.

If you do a calibration from the beginning, you should start by setting the zoom on your physical camera, preferably starting from the lens's minimum focal length. Then take note of the 'Sensor Zoom' value from the incoming zoom tracking data alongside the 'Focal Length' indicated on the camera's lens.
Next, focus solely on adjusting the focus, keeping the previously set zoom constant. During this phase, capture the various 'Sensor Focus' values and their respective 'Focus Distances', ensuring the zoom values remain unchanged throughout this procedure.
After fully documenting the focus adjustments at one zoom setting, you can change the zoom to a different value and undertake the same process.

Warmest regards,

Hi,Eifert

 In Edit calib point interface，the focus distance value matters? it's always remain 0 m,i did't change it during the process.

My process is as follows, first , i select the maximum and minimum points of focus at a zoom point to calibrate, untill now, change the focus between these two points, the tracking is all good. When I select the next zoom point and repeat the above steps, the problem arises.  and You can see that in the picture, I change zoom, and when interpolating, the auto-filled FOCUS LENGTH is outrageously wrong, of course I can calibrate it back, but at this time, if I change focus, the virtual distortion will become unstable

Do you have any suggestions? I've tried other sequences of adding points as well, but at the moment, it looks like the issue arises once the calibrated points involve different focuses

Hi Dan,

I think it's important to clarify that Focal Length and focus are not the same things. Focal length actually refers to the zoom unit of measure commonly used with lenses.

If you want to do also focus calibration, not just zoom calibration, then you will have to specify the Focus Distances for each calibration point.

The Focal Length value in your screenshot seems to be incorrect as it is less than the previous values, while the Sensor's zoom value increased.

Warmest regards,