Hoya Y7POLC049 Fiche technique télécharger pdf (Page 50)

How another Large Manufacturer

makes Filters

Imagine a sandwich made with a thin gel or even colored glue

between two pieces of regular glass, similar to the glass used in

windowpanes. This is how some other brands of optical filters are

made. These types of filters are cheap to produce, but inferior for

several reasons:

1. Over time, the expansion and contraction of the different

materials can lead to delamination, which is a separation of the

different materials. This will show up as bubbling, peeling, or

discoloration, rendering the filter useless.

2. The color of the gel can shift or fade over a relatively short period

of time and will not yield the same color rendition.

3. If all six surfaces, three layers, two surfaces each, are not perfectly

flat and perfectly parallel, the filter causes a “lens effect” which

degrades the optical performance, or in extreme cases, shift or

limit the focus of the lens it is used with.

How Hoya Makes Filter Glass

To make it’s filters, Hoya adds different raw elements, like gold, and

chemicals compounds to its optical glass silicates while mixing in a

molten state. To insure consistency in glass manufacturing, Hoya uses

a furnace called an Automatic V blender to mix the different materials

continuously at a highly controlled rate. This ensures that Hoya filter

glass is uniformly colored all the way through. There is never any risk

of uneven coloration, shifting or fading of the color, or delamination.

The two surfaces are ground and polished for perfect flatness.

Not to scale

Regular Glass

Colored Gel Laminate

Regular Glass

Not to scale

Uniformly Colored Glass

ALL FILTERS ARE

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Hoya Y7POLC049 Fiche technique Page 50