Which Gossen do you compare it to? The reading in the viewfinder is LV or EV for ISO100 although Pentax called it EV. Luminance to LV is a little bit different on each meter depends on the K factor. Pentax manual said that at EV 1 (for ISO 100) it's 0.28 Cd/m^2 so the K factor is 14. Gossen may use a K 12.5 but it's only about 1/6 stop difference. A reading of 2 stops different then one or both meter must be wrong or the Gossen is not a spot meter (incident or wide angle reflective).