How many observations should I do for my lens?
It’s very difficult to say, there isn’t one way that works for all lenses.
A high quality broadcast lens may only need a calibration point for zoom at every 20% step and then each at 0% and 100% focus.
On the other hand, a compact wide range PTZ camera every 5-10% step on zoom and possibly also another point in the focus range.
We recommend starting with 20% zoom steps and then checking the interpolated values precisely between two calibrations in the distortion viewer.
If the result does not match good enough for your requirements it´s always possible to add calibrations in between afterwards.
My screen is out of focus, I can´t calibrate this point?
Some focus level´s can not be calibrated, depending on camera, screen size, resolution and room space.
This is nothing to worry about. Just go as close as possible to a focus step which can be calibrated.
If needed, non-reachable calibration steps can be manipulated within the lens profile manually afterwards.
What size should have my markers?
The more markers the calibration system can see, the more points are avaiable for the calibration.
This is good for calculation of the lens distortion.
But at the same time the markers should not be to small, as the system needs to interpolate pixels.
So at the end how small/big the markers should be depends on the resolution of the camera image.
The markers should not be much smaller than what is shown in the below image:
The markers should not be much bigger than what is shown in the below image:
