See the main Beta Pictoris page for full details: http://www.pbase.com/rolfolsen/beta_pictoris

I have found that the limiting magnitude with the ToUCam from my location is around 20.0. So how far out should the debris disc theoretically be visible in my image? This is a plot of the magnitude pr. square arcsecond for the debris disc (Smith, B. A. & Terrile, R. J. 1984, Science, 226, 1421 A Circumstellar Disk around Beta Pictoris)
It seems that if a limiting magnitude of approximately 20.0 is assumed, then the debris disc should be visible out to somewhere around 250-300AU. This corresponds with what is seen in the profile plots.