Digital HST has a more accurate trip point at end of test – not subject to misalignment of read and black needle meters, nor to turns counting dial being misadjusted.
Reference Sensor in Analog HST runs well into forward bios, which causes loss of signal inside the sensor, and improper response to changing illumination level. Forward bias is also temperature sensitive.
Forward bias sensor issues are designed out of the digital.
(Early digital models had some forward bias sensor problems – those models we can upgrade with new sensors).
Less temperature sensitive – Analog will drift during warm up (due to reference sensor forward bias) and will also respond to room air temperature changes.
Digital shows actual reflectance on display as a sizing test progresses. Analog does not – the micro amps indicated on the meter by the moving meter needle do not show actual intermediate reflectance’s.
Digital HST works internally with high resolution, and averages many quickly-taken readings continuously.
Digital is easier to calibrate to a fresh piece of paper quickly and accurately.