Points to note:
1) Move the compass to "trigger" measurement.
2) If the error is large, repeat the measurement, holding still until the error subsides.
3) Measuring beneath dark overhangs with the rock face at arm's length overhead is difficult with analogue compasses, but the listerCompass can be used with the iPhone upside down to measure the orientation of bedding, foliations and/or lineations.
4) Use the annotation feature to record information as you go along, e.g., enter the sample ID. Remember that the listerCompass can simultaneously record both foliation and lineation data, thus considerably reducing the amount of effort required on an outcrop.
You can turn the GPS on/off in the Settings Panel.
Once a measurement is saved, before measuring again, tap "start measuring".
Request improvements (or report errors) clear_range (at) yless4u.com.au
Protect your iPhone. Field work is not likely to improve its looks.
Practically speaking, at least to make the batteries last longer, I purchased a red http://www.mophie.com/ and it is great.
Version 4 allows more flexibility as to how to use the compass. To avoid unnecessary bother, most buttons must be double tapped before any action ensues. Double tap to change the mode for example. To lock (or unlock) settings go to the data screen. Use the switch to prevens settings from accidentally changing while the iPhone is in your pocket.
Touch the "Information" button to see your data. Collected data is stored and can be edited and sent by Email as an ASCII file with XML tag, or as textTAB delimited data. You can also save it on your iPhone, with a timeStamp, so accidental overwrites do not happen and access the data using the iTunes file sharing capability.
Test any compass app by tilting the iPhone to a steep orientation, or by slowly twisting it, or holding it upside down. The listerCompass computes direction using primitive trigonometric functions with smoothing functions and error monitoring. Heading is the trend of the long axis of the iPhone.