Nokia RM-596 Service Manual

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Contents

Nokia RM-596 Service Manual Manual pdf 178 page image

Sensitivity Camera module's sensitivity to light. In equivalent illumination conditions,a less sensitive camera needs a longer exposure time to gather enoughlight in forming a good image. Analogous to ISO speed in photographicfilm.Sharpness Good quality images are 'sharp' or 'crisp', meaning that image details arewell visible in the picture. However, certain issues, such as non-idealitiesin optics, cause image blurring, making objects in picture to appear 'soft'.Each camera type typically has its own level of performance.Shutter The electronic shutter is used when short exposure times are needed andin video. When the mechanical shutter is used a black sheet will cover thelens after the exposure.The effect of image taking conditions on image qualityThere are some factors, which may cause poor image quality, if not taken into account by the end user whenshooting images, and thus may result in complaints. The items listed are normal to camera operation andare not a reason for changing the camera module.AutofocusWhen the camera is focusing a lens is moved inside the module to give the sharpest possible image. Thiscamera module is specified to operate satisfactorily from 10 cm to infinite distance of scene objects. Tryingto photograph objects closer than 10 cm is likely to result in a blurred out of focus image. The lack of sharpnessis first visible in full resolution images. Images taken very close to the subject, a limited depth of focus willbe visible, that is the upper or lower parts of the image may be out of focus. This is normal; do not changethe camera module.Figure 29 Only center part of image is in focus due to limited depth of focusThe amount of light availableIn dim conditions camera runs out of sensitivity. The exposure time is long (especially in the night mode)and the risk of getting shaken (= blurred) images increases. In addition, image noise level grows. Themaximum exposure time in the night mode is ¼ seconds. Therefore, images need to be taken with extremecare and by supporting the phone when the amount of light reflected from the target is low. Because of thelonger exposure time and larger gain value, noise level increases in low light conditions. Sometimes blurringmay even occur in daytime, if the image is taken very carelessly. See the figure below for an example. Thisis normal; do not change the camera module.RM-596Camera Module TroubleshootingPage 5 – 6 COMPANY CONFIDENTIAL Issue 2Copyright © 2010 Nokia. All rights reserved.