1. Filter that fail the collimator test


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    The apparatus on the counter is a simple collimator used for testing the optical clarity of filters and other optics. On one side is a light source shining into an "eyepiece" that contains a test chart. The image of the test chart is projected through one telescope into the other. The other telescope has a video camera attached to it's eyepiece so the test pattern can be displayed on the LCD TV mounted above. The stack of circular polarizing filters shown at the beginning were collected from various places, most are made in India or China regardless of what name is on them. They all look fine and clear if you look though them but when when tested by the collimator you can that these filters degrade the image quality so much the test pattern cannot even be seen. It would be impossible to get a sharp picture when photographing with these filters. As you can see the final filters is a Hoya HD circular polarizing and it has almost no optical effect on the test pattern. This is how a filter should perform in this test. What Hoya was demonstrating at the Photokina show was even if a filter looks clear to the eye, if you do not know the source of the glass it could have a very bad impact on your photos.

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