I have the ZWO ASI120MC, and I have no problems at all with it. I have been running it from three different computers:
. a 5-year old Windows 7 laptop (dual-core processor, 32-bit Windows 7, 2 GB RAM)
. a 4-year old Windows 8 laptop (dual-core processor, 64-bit Windows 8.1, 4 GB RAM)
. a brand-new Windows 8 tablet (quad-core processor, 32-bit Windows 8.1, 2 GB RAM).
Can you tell us a bit more about your set-up - processor, RAM, OS, drivers, software versions, etc.
I have been mainly running with the latest "development" versions of FireCapture (2.4 Beta) and AutoStakkert (2.3.0.21 Alpha), but the older "stable" versions work fine too. I only tried AmCap and SharpCap sufficiently to make sure they work, but I am now focussing on FireCapture to capture my images and video, and AutoStakkert for stacking, as well as playing with RegiStax and DeepSkyStacker to see which I like best.
The only problem I have found is that I sometimes lose some frames if I connect to a particular USB port on the oldest laptop, but it works fine if I connect to a different USB port, so I suspect the particular USB port could be "flaky". Note that on the product website
http://www.zwoptical.com/Eng/Cameras...ware_index.asp , it says that "some USB3.0 ports are NOT compatible" - but that's probably not an issue if you're running an old computer - but try using a different USB port and see if that fixes the problem.
As others have said - make sure your device drivers are the latest downloads from the website; don't just use the ones that came on the disc.
I don't think the optical attributes of the telescope would have any impact - you should be able to do all of the bench testing you need with the camera sitting on the desktop next to your computer.