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Home You Are Here ->HOYA FILTERS->BOTH SIDES COATED FILTERS

align="center" class="style1" style="margin-bottom:0;">How another Large Manufacturer makes Filters

            

Some filters are made with a thin gel or even colored glue laminate sandwiched between two pieces of regular clear glass, similar to the glass used in windowpanes. 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 de-lamination, which is a separation of the different materials. This will show up as bubbling, pealing, or discoloration, rendering the filter useless.
2. The color of the gel can shift or fade over a relatively short period of time.
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 Filters

            

            

To make colored filters, Hoya adds different raw elements, like gold, and chemicals to its optical glass while it is in a molten state. This insures 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.