One thing to keep in mind is that the Ultrascope (like other current WFMs) is a "software scope" in that all of it's functions are being performed in software based on a digital signal, just as with CF's internal scopes. Everyone is reading the same digital numbers. So there's nothing inherently "more accurate" about an outboard scope.
That said, external scopes do offer some advantages. Because they are reading the signal just before it goes into the monitor/VTR/etc., they are reading the signal *after* any possible distortions, gamma changes, etc. that might occur in the signal path between the CF plug-in and the output BNC. There shouldn't be any, but there can be.
On the other hand, most people are delivering digital files these days, so there is still the possibility that the files you encode won't be seeing the same signals that make it out to your monitor since they take different paths. The only way around this whole issue is to make sure that you know that everything matches by careful testing. An outboard scope is a useful tool in doing this testing, but it doesn't magically eliminate the problem or the need for care.
Another advantage of outboard scopes is that they can show you non-active parts of the SDI signal which aren't shown (because they don't exist yet) by CF and other internal scopes. If you're troubleshooting SDI cabling problems this can be handy. But you need to know what you're looking at, which is more than most motion graphics people want to learn (not sure what your application is).
Outboard scopes show all lines in the video signal, which CF also does, but some internal scopes. Only sample every 16 lines or so (hello FCP!) really isn't that useful.
Outboard scopes may also have audio displays which can be useful.
A further complication is that more people are monitoring using HDMI connections these days, and external scopes accept HD-SDI on BNC connectors. The conversion between the two is another source of possible error that just having an outboard scope won't fix.
And nothing against the Ultrascope, but you should also consider outboard products from Tektronix and Leader. By the time you assemble a scope from Ultrascope (adding the computer, monitor, etc.) it may cost just as much, and the other alternatives are a lot more portable.
So have I helped at all, or just confused matters more?
Bob Currier
Synthetic Aperture
