AS ISO 20954.1:2019 pdf download.Digital cameras – Measurement for image stabilization performance Part 1: Optical systems.
4 Measurement method
4.1 General
The objective of this document is to specify how to measure optical image stabilization performance of a camera held in the user’s hands. Accordingly, a measurement session would better simulate a real shooting situation if the camera was actually held by a test photographer. However, this makes it difficult to eliminate variation among individual photographers or how well the camera is designed for handheld shooting. In order to cancel these effects, the test camera shall be mounted on a vibration generator that shakes the camera with a simulated handheld vibration waveform, and image stabilization performance shall be measured with images of a test chart specified by this document. This document specifies two waveforms that simulate the important characteristics of how a camera shakes when it is held by hand. These waveforms were developed by analysing extensive measurement data and adding further theoretical observations. Figure 1 shows an overview of the measurement method. Annex E collaterally gives additional
explanations for background of specifying measurement method, vibration generator, vibration waveform and reference information.
4.2 Equipment and environment for measurement
4.2.1 Test chart
For this document, the test chart shall meet following requirements. Specifications and usage of the test chart are described in Annex B and alternatives are described in Annex C.
a) The chart shall contain orthogonal edges consisting of a dark portion and a bright portion near the centre.
b) The contrast ratio of the dark portion to the bright portion shall be 1:4 or more.
c) The dark and bright portions shall be wide enough to accommodate the total image degradation which is described in 4.4.1, when the image stabilization (IS) function is OFF within the exposure time range for measuring the image stabilization performance.
4.2.2 Lighting
Lighting shall be flicker-free. The light source should illuminate the chart with minimal direct reflection and illuminance variation.
4.2.3 Temperature and humidity
The temperature and humidity should be (23 ± 2) °C and 30 % to 70 %, respectively.
4.2.4 Vibration generator
4.2.4.1 General
For the measurements in this document, a CIPA-certified vibration generator should be used. If a non- certified vibration generator is used, it shall satisfy the amplitude and phase characteristics under the excitation conditions specified in 4.2.4.2.
4.2.4.2 Excitation conditions
This subclause describes the required specifications for the amplitude and phase characteristics of the vibrations generated by the vibration generator excited with sine waves. Table 1 shows the properties of the sine waves that shall be used to measure the amplitude and phase characteristics. Table 2 and 3 respectively show the input sine wave combinations that shall be used to measure the vibration amplitude characteristics and phase characteristics. To measure the amplitude and phase characteristics, the vibration generator shall be excited in both yaw and pitch directions simultaneously, carrying a load weighing at least as much as the test objects, i.e. camera, storage media, battery and lens. Figure 2 is an overview of how to verify the vibration generator using these waveforms.
4.2.5 Vibration waveform
There are two types of vibration waveforms that shall be used to verify optical image stabilization performance: WB-L and WB-H defined in Annex A. One or both shall be used based on the total mass of the test camera according to the following criteria. Total mass refers to the camera body, including storage media and battery, and lens.
— Selection criterion I: WB-H shall be used for a total mass of 600 g or more.
— Selection criterion II: WB-L shall be used for a total mass of less than 400 g.
— Selection criterion III: Both WB-L and WB-H shall be used for a total mass of 400 g or more but less than 600 g.
Both waveforms consist of two axis components: yaw and pitch. Both yaw and pitch components shall be excited at the same time (see Annex A).
4.2.6 Shooting distance
The shooting distance should be about 20 times the 35 mm film equivalent focal length.
If the space does not allow this shooting distance, the distance may be changed to the maximum amount available. But even when in this case, in order to avoid significant shifts orthogonal to the optical axis, it is desirable that the shooting distance is as close to 20 times the 35 mm film equivalent focal length as possible.AS ISO 20954.1 pdf download.