Konica Minolta LS-100 Luminance Photometer

Konica Minolta LS-100 Overview

The portable LS-100 employs a silicon photocell that is spectrally matched to the CIE V(λ) photopic observer function. The single lens reflex (SLR) optical design allows the operator to conveniently view a display or light source through the eyepiece and then focus and align a central black measurement spot within the target object. The LS-100 features a fixed 1° measurement field-of-view that corresponds to a minimum measurement spot size of 14.4mm at the minimum working distance of 1014mm. The LS-100 reports luminance in units of candelas per square meter (cd/m²), or in imperial units of foot Lamberts (fL).

Measurement Range & Accuracy

The LS-100 provides luminance measurements over the range from 0.001 to 299,990 cd/m². As a point of reference, the brightness of a typical flat panel display (LCD) will be about 500 cd/m². The silicon photocell is spectrally filtered to match the CIE V(λ) photopic observer function with an f₁’ (DIN 5032) of 8%. Pro-Lite’s LS-100 is supplied with an up-to-date calibration (performed within the previous 12 months) and calibration certificate. The calibration is performed using standards that are traceable to a National Measurement Institute (NMI).

Measurement Spot Size

Luminance meters are often referred to as “spot photometers” due to the fact that the measurement of luminance is made from a defined spot or area on a light source or display. When making luminance measurements it is vital that the measurement spot (as denoted by the central black spot viewed through the eyepiece) is located well within the target area on the object. If the measurement spot only just fits within the lit area, or overlaps any of the surrounding unlit area, the resultant luminance measurement will be erroneous, possibly to a significant degree. 

As standard, the LS-100 has a minimum measurement spot of 14.4mm diameter at a working distance of 1014mm. Two accessory close-up lenses are available to rent that attach to the input to the LS-100 and result in a smaller measurement spot size. With the model 110 lens fitted, the spot size drops to 1.3mm, while with the model 135 lens attached, the measurement spot diameter becomes 5.2mm.   

Low Flare SLR Optics

The LS-100 employs flare-less SLR optics for the highest possible accuracy. The degree to which light outside of the defined measurement field-of-view can influence the measurement is an important factor in the design of luminance meters. In the design of the LS-100, Konica Minolta kept the lens flare factor below 1.5%. So even if there is a very high luminance object just outside the LS-100’s 1° field-of-view, it will not contribute to the readings.

Other Important Information

Basic operation of the LS-100 gives you readings of the target object’s luminance in cd/m² (or you can select foot Lamberts if you prefer). Advanced operation allows you to hold a reference reading in memory and compute a luminance ratio for the currently measured luminance. You may also enter a colour correction factor specific to the type of light source under test. The LS-100 features an LCD display located on the side of the main body, while a secondary display illuminates within the eyepiece field-of-view after the measurement trigger has been pressed and once a measurement has been recorded. The CL-200 operates from a single 9V battery (non-rechargeable).