Ron Clanton replied to the topic 'Focus routine not working' in the forum. 2 months ago

I'm not an expert, but there were a lot of improvements in the autofocus process with version 3.5.4. Prior to this version, I had a lot of trouble with polynomial focusing (same as your experience) and had to use linear to make it work. Under 3.5.4 I have not had any problems with autofocus and it is very fast.