Originally Posted by Troubador
See Henning's description which is correct. But I just didn't find this a problem although I can understand why it can sound like one. The zoom ring and the focus ring are next to each other but of different sizes and have very different resistances to overcome so you always know which you are turning. I just didn't have a problem in arriving quickly at a perfect focus and I have always been in love with my old Diascope because of its two separate knobs for fast and slow focusing. This system on Harpia worked fine for me and I was rather skeptical at first.
I've birded with the scope during a test week and didn't find it a problem either. I found it quick and easy to find the right focus and finetuning it. Didn't have the opportunity to compare alongside any of the competitors, but sharpness, clarity and the impression field of view through the entire zoom range gave a very good impression.