Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Does the c920 offer the capability to zoom?
Document: Another logitech winner this is a great camera giving lots of verstitality with its on screen controls for its tilt/pan and zoom capability
This webcam is outstanding and is a must have for anyone doing streaming wether on a Mac or a PC.It is our prayer that Logitech will work on a 920 with the capability of adapting Canon EF lenses for optical zoom. This would be a dream come true for streaming community.
I thought about this further over the weekend, and now think I could live without it or simply use my 9000 if I really need zoom. I did like the fact that the video with the C920 would not stutter at high resolution, which my 9000 will do at 720p, make the c920 a good fit for me afterall.
the picture is stunning definitely the HD it promises. I was slightly disappointed to discover they no longer offer the special effects
I realize that this is made for PC. However I took a chance and bought it for my mac because the specs were the best logitech had to offer. It works just fine for Skype, but all of the controls are hidden away for PC users only.
I thought that somehow it would provide more capability than my iMac's built in camera. That wasn't the case. If you have a Mac, save your money, and just go with the built in product.
I was looking for widescreen format, HD capability and omni-directional sound - I found them all in this unit. The lens really makes it. For the money you just can't fint a better webcam. Thank you Logitech.
Devive does excelent video, but is poor that it needs drivers (100mb download at that) for just the most basic webcam capability. Many of the lesser models are plug in and go. does not pack well for a backpack or similar if you travel a lot. Its a much better deivce on a tripod vs monitor mount.
It's super clunky to get at camera controls. The controls offer no keyboard shortcuts so you're constantly trying to click on mouse buttons to adjust. If you use a Windows 8 app to make video calls/record, the controls will not pop up on top of the app screen. It pops up on the desktop screen only. The windows 8 camera app does not offer any controls and instead just offers a record/stop record button.
Scouring through webcams to find one that was both Windows 7 and Windows 8 compatible narrowed it down to this model. There is very little information on the web about Windows 8 compatibility and at the time of purchase this was a gamble. There are many cheap webcams out there. This was well worth the cost. Not only is the camera spectacular but the microphone works perfectly. When I first used this with Windows 8 I was stunned by its capability; just a gorgeous picture.
Answer: For Mac use eCamm's  "iGlasses"  webcam controller software to zoom  (and also to control manual focus, manual exposure on the C920 running on a Mac. )  Logitech's  C920 webcam software isn't officially supported for Mac , but iGlasses will do what you need.http://www.ecamm.com/mac/iglasses/