LukeM wrote:Except that a Suunto is calibrated to something like +/-.25 degrees while the Theodolite developer is claiming 2-5 degrees accuracy in the best case. Not sure how scientific he is being there, but that doesn't give me a lot of confidence in the device as a compass
The accuracy statement for the iPhone / Touch probably comes from some internal algorithm related to external (and maybe internal to the device) magnetic interference levels and not the capabilities of the sensor.
I know Suunto compasses are calibrated for inclination by zones of the earth, 'cause the box says so, but I was not aware of another calibration done by Suunto.
There are three obvious ways I can think of to compare a Suunto to an iPhone/Touch head to head: cave survey, run a loop, or run a compass course. I have surveyed with both and run them on my nearby compass course (with a known bearing to true north). I have not yet run a loop. This was not enough to draw a conclusion other than more testing would be worthwhile.
My gut is to go with what I know, the Suunto, but I want to know more.