jueves, 12 de noviembre de 2015

Optoma HD25-LV lumens and contrast ratio test review

The present study evaluates a production unit of the Optoma HD25-LV projector. Illuminance and contrast ratio measurements were performed on this system according to IEC 61947-1:2002.

The projector excluded the screen produces light output (illuminance) of 2037 ANSI lumens at 1080p and contrast ratio of 331:1

Fig. 1 - Optoma HD25-LV

I provide below a description and details of the setup procedures used to prepare the proyector for measurements according to ANSI . 
  • Section 2 presents the test requirements.
  • Section 3 shows the measurement setup.
  • Section 4 provides the instruments to be used.
  • Sections 5 and 6 results and conclusions.

  • The Optoma HD25-LV delivers outstanding high-definition 1080p video and graphics.
  • According to manufacturer the HD25-LV has 3500 ANSI lumens and 20,000:1 contrast ratio.
Projector and measurement test setups were according to IEC 61947-1.
Pattern used:
ANSI screen locations for measurement the light output in lummens
Fig. 2 - White test pattern specification
For test purposes readers can download the figures 3 and 4  ready for 1080 in aspect ratio 16/9 to test their systems.
Test pattern for ANSI light measurements
Fig. 3 - White test pattern

Contrast pattern for ANSI light measurements
Fig. 4 - Contrast pattern

The projection system was setup according to the figure 5.
  • Projection distance (D): 3.40 meters approximated.
  • Screen width (W):  2.245 m
  • Screen height (H): 1.265 m
  • Area (W*H): 2.84 m2
Test setup for testing optoma HD25-LV according to IEC 61947-1
Fig. 5 - Test setup
Brightness and contrast controls were adjusted to achieve visually distinguishable steps of a gray scale pattern (figure 6). Lamp mode was configured to maximum power. Other adjustments were made as indicated in figures from 7 to 10.

Gray scale pattern 1080 according to IEC 61947-1
Fig. 6 - Gray scale step 8

Software projector configuration was as indicated in the following figures.

Display configuration OPTOMA HD25-LV
Fig. 7 - Display configuration
Image configuration OPTOMA HD25-LV
Fig. 8 - Image configuration
Advance image configuration OPTOMA HD25-LV
Fig. 9 - Advance image configuration
Color space configuration OPTOMA HD25-LV
Fig. 10 - Color space configuration

The screen illuminance were measured with a light meter. The sensor was placed on the plane of the focused image at the centre of each of nine points indicated in the figure 11. In this case, illumination sensor was placed on axis with the projector light ray in order to correct the cosine effect and maximize the flux entry into the sensor as indicated in figure 11.

Lux meter alignment
Fig.11 - Sensor alignment

Instruments used in these test include:
  • Illumination meter DX-200
Illumination meter
Fig. 12 - Illumination meter



The average of the nine (points 1 to 9 in figure 3) readings in lux (lumens per square metre) was multiplied by the number of square metres covered by the image at the plane of the meter readings. The result was taken as the light output of the projector, in lumens.

Optoma HD25-LV illuminance test IEC 2002
Fig. 13 - Optoma HD25-LV illuminance test IEC 2002

Based on the measurements taken, illuminance measured according to the ANSI procedure yielded a 9-point average of 2037 ANSI lumens with a variation of 13.6 % greater than average, and -41.3 % less than average for the thirteen ANSI screen locations shown in figure 13.

Note: It has to be emphasize that at the time of this test, the life of the lamp was 160 hours.

Contrast ratio is the ratio of higher illuminance to lower illuminance. Illuminance measurements in lux was made at the centre of each of the bright (white) rectangles and the dark (black) rectangles. The average illuminance value of the bright rectangles was divided by the average illuminance value of the dark rectangles. The contrast ratio was then expressed as this ratio:1 (e.g. bright rectangles with an average value of 15 lx and dark rectangles with an average value of 0,10 lx provide a contrast ratio of 150:1).

Illuminance was measured in both horizontal and vertical directions at 16 screen positions for white and black rectangular targets simultaneously displayed in a 4 x 4 chess board configuration as specified by ANSI IT7.215.

Optoma HD25-LV contrast ration test IEC 2002
Fig. 14 - Optoma HD25-LV contrast ratio test IEC 2002
Based on the measurements taken (figure 14), Contras Ratio computed from measurements made under dark room conditions yielded a CR = 331:1


  • The collected data reveals a clear difference between the manufacturer data and the test results
  • There is a clear discrepancy between the manufacturer illuminance (3000 lumens) and the data obtained (2037 lumens).
  • The same clear discrepancy is observed between the manufacturer contrast ratio (20000:1) and the data obtained (331:1). However, it has to be empathized that for this measurement, dynamic black was setted to off.
Seeing those data, we can scold Optoma for their advanced “optimism” (or total lack of reality) but the bottom line is that roughly 2000 measured lumens is a lot of lumens, and makes this a projector that can tackle many family rooms and living rooms while providing a good picture.

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