Data Sheet

Filter Quality Comparison

The apparatus on the counter in the image below 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 its eyepiece so the test pattern can be

displayed on the LCD TV mounted above.

There are so many circular polarizing filters in the world, most are

made in India or China regardless of what name is on them. They all

look fine and clear if you look through them but once tested by the

collimator you can find that these filters degrade the image quality so

that the test pattern cannot even be seen. (See the image left below)

It would be impossible to get a sharp picture when photographing with

these filters. The test pattern shown right below is shot with Hoya

circular polarizing filter and it has almost no optical effect on it.

This is how a filter should perform in this test.

We’ve Been Framed!

Hoya believes the filter frame is an extremely important part of the

filter as well. Hoya created precision machined aluminum frames to

hold their high quality glass. They prefer aluminum to other materials

because it is strong enough to hold up to years of use. Some say that

brass is the best material to use. However, Hoya doesn’t hold that view

and here is why; brass is a far more rigid material than either aluminum,

or other materials that are being use in today’s lens barrels. This means

that, should the front of the lens get hit, the rigid brass filter ring will

transfer almost all the force of the shock to the lens barrels and

mechanics within the lens. An aluminum filter frame will absorb some

of the shock by bending, and at a certain point the glass will chip or

break, which is what the filter is supposed to do, protect the lens!

Replacing a filter is always preferable to getting a lens repaired.

THE DIFFERENCE

Other brand circular polarizing filter

HOYA circular polarizing filter

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