I don't know if my experience is an anomaly for Zeiss HR or not, because my experience seems contrary to the other reviewers. My interview process lasted 4 months and consisted of 3 interviews.
I applied online in June and was scheduled for a phone screening within 3 days. I had a nice, cordial screening interview which lasted 45 minutes. I was told the screening process would be completed by July 4th and second round candidates would be brought in for 1:1 interviews. I hadn't received any feedback so I followed up in mid July by email. I was told the process was taking longer than expected, but that I would hear from HR shortly.
I was scheduled for a 1:1 interview with my potential boss at the beginning of August. Interview was scheduled for 1 hour, but actually lasted closer to 2.5. Very nice interview mixed with formal and informal questions on experience and management style. I was impressed with his attention to detail and that he took the time to explain the products along with Zeiss's goals for them.
I was scheduled for a second 1:1 interview with VP of Sales, VP of Marketing, and HR manager about one week later. Interviews lasted about 3 hours and consisted of typical form questions and personal conversation. The next step is the process was an interview with the GM for candidates who made it to the third round. This was expected to take place the last week of August.
I hadn't received any feedback (positive or negative) so I followed up with my contacts to see if I hadn't been selected for round 3 at the end of August. I was told the process was moving slower than expected but to be patient. Honestly at this point I thought my chances were 50/50, because I thought I connected with one of the VPs, but not the other one. I still hadn't received any feedback by middle of August so I called yet again, primarily to get closure on the opportunity. Yet again I was told to be patient and that the process was taking longer than expected. I waited until the end of the first week of October to connect with my contact, at which point he told me they went in another direction and was surprised HR hadn't contacted me.
I was impressed with the people I met, but would characterize their HR process as unprofessional and unnecessarily long. Throughout my interview process I invested 4 months of time, multiple vacation days, hours in the car, hours of prep time, and multiple closure phone calls........and at the end of it HR didn't even feel the need to send a polite "We appreciate your interest, but we've chosen another candidate email". I consider that a red flag and would warn other candidates to set their expectation of Zeiss HR accordingly.