Fill volume for 5 and 3 mm NMR tubes

While 5mm NMR tubes are the default size for solution NMR, several alternatives are available. For those with less sample 3mm, 1.7mm, and 1mm NMR tubes are available. The 1.7mm and 1mm NMR tubes really require a microprobe with reduced diameter coils, but 3mm tubes can be used in a 5mm probe. With our 1.7mm probe out of action I purchased a 3mm spinner and ran some spectra to compare the fill volumes of 5mm and 3mm tubes in our 5mm BBI probe.

Fill volume for 1.7mm NMR tubes

The SSPPS NMR Facility routinely uses a 1.7mm micro-cryoprobe that takes capillary NMR tubes with a diameter of 1.7mm instead of the standard 5mm NMR tubes. These capillary tubes require much less sample volume than a standard tube, but exactly how much should be used? And what happens if there is too little? Or too much?