Hello nice people. I am absolutely new to film making but nevertheless I have a question. I want to follow-focus a falling marble, that falls down 1 meter in about 300 ms.
One of the topics that arose while investigating how to do that is how lenses respond when the focus ring is turned step by step by a motor. I investigated a Sigma 24mm 1.8. The stepper motor I used initially did 200 steps for a full revolution. It took 107 steps to focus from closest focusing distance to infinity. Please have a look at the image I attached. The curve can be well described mathematically with a growth curve.
Now my question is this: Would you think that other lenses have similar looking curves, maybe a little flatter or so? Or: Did you ever recognize a lens as responding maybe with a "weird" curve with sort of tales or so?
Or even better: Is there any documentation anywhere out there about this topic?
Here are my first tests: