In order to get an ideal field of view (FOV) for different video surveillance environment, many IP cameras are equipped with vari-focal lens which allow user to adjust the camera focal length. When I browsed Messoa FAQ section in web page, I found a document which teaches users to adjust focus for a clear picture on the megapixel IP camera. Herein we publish its content with purpose to let more people know the correct method to adjust focus on camera.
In this article, we give an explanation about the lens resolution characteristic that will result in focus unbalance problem of mega-pixel camera according to the lens test data and propose a "full screen focusing" criteria that shall be applied on production line for mega-pixel lens focus alignment to obtain clear focus on both side of image.
Unbalance resolution on both side of a mega-pixel lens may occur due to process variance during the glass grinding on production. As a consequence, the traditional central focusing criteria for focus alignment may not be a good way to guarantee a clear image on both sides of mega-pixel cameras. To overcome such problem, we propose a so-called” full screen focusing” criteria that takes left, right and center image into consideration simultaneously as adjusting the focus so a balance and clear image is achievable. Finally, we explain the unbalance phenomenon form lens inspection data to give users a concrete understanding of root cause of this problem.
1. As unbalance focus situation (left or right) occurs.
2. Please adjust the "Focus" rod slightly for a balanced focus on both side of image.
3. Please follow “full screen focusing” principle, i.e. checking left, right and center simultaneously, to do focus alignment for a consistent focus on whole screen.
4. Root cause of focus unbalance:
10 pcs of lens were tested and the resolution data for 9 points at TELE, MIDE and WIDE, A~I,are recorded in the table below:
From the table above, we can conclude that:
(1)Test result on TELE : average resolution for C, D, E is lower than G,H,I.--> A little unbalance.
(2)Test result on WIDE: the resolution on one side(E,F ~143) is worse than the other side(I,B ~ 170) UNBALANCE
(3)Test result on MIDE : The best of all, i.e.,the resolution on left,right and center is all most same.
Due to the lens resolution unbalance phenomenon, we have to use "full screen focusing" criteria on focus alignment for an optimized clear image.
The above content and images are from MESSOA Technologies Inc, Established in 2003, MESSOA Technologies Inc. specializes in surveillance technology, offering security and surveillance cameras with comprehensive network solutions.
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