There is a box to check in the Trimble Calibration Menu to hold the scale factor to 1. I've not noticed a scale factor being introduced in a two point calibration, but I've seen some wacky results with three and four point calibrations. I've never gotten a straight answer from Trimble on exactly what a three and four point calibration does. Is it rubber sheeting or what?
If you're just using a site calibration to search corners a reasonable scale factor wouldn't affect much.
The question is. Should you remove the calibration when you download the points to draft the job? Then you would have unadulterated coordinates to work with.
The wild card I find with any calibration comes down to?ÿwhat I call the?ÿ'ghost in the machine'.?ÿI can rarely be 100% certain exactly what voodoo the software has?ÿworked on?ÿmy coordinates in the data collector.?ÿIn light of that I'll typically post process the raw GPS observations in a standard projection to get a better handle on the nuances of the coordinates I'm working with, how my survey relates and hopefully throw some light on any skeletons hiding in the shadows. As usual, it depends on how comfortable you are with the end results and the particulars of the mission. Where I've run into problems is mixing a calibrated RTK survey with conventional instrument work in the same Trimble?ÿ.job file. Using a standard projection without any calibration this?ÿhasn't been a problem. I've seen some?ÿserious fubar surveys?ÿresulting from calibrations that flew right over the head of the surveyor because they didn't take the additional step of understanding exactly what their calibration had been doing.
Just because I'm paranoid, doesn't mean they aren't out to get me.