confused with plots - Rn vs. cycle & delta Rn vs. cycle - (Oct/30/2008 )

I'm new to real-time and reading around for the last 6 hours trying to clear myself up on analyzing the data.

Anyway...we're working with the ABI 7900, and we can view the amplification plot in Rn vs. cycle and delta Rn vs. cycle. I am confused as to what the difference may be representing between the 2 plots.

And may I also clarify as to the setting of the threshold for determination of Ct.
Sorry for my naiveness, but it seems to be that when in the Rn vs. cycle plot, the threshold is set at the beginning of the exponential phase. While, in the delta Rn vs. cycle plot, it seems that threshold lies right in the middle of the exponential phase?

I appreciate any input to resolve my stupidity!

From what I remember from working with ABI machines, delta Rn is a standard view to work in, and it represents data baseline corrected and/or ROX corrected.

About the treshold.. do you have any screenshots?
There may be also different scales on each view (linear vs logaritmic) apart from Rn, but it's hard to say.