Hoya Multi-Coated Technology (HMC)
To provide photographers with a higher quality professionals require, Hoya created the Multi-coated line of filters. These filters have a 3 layer coating system that further reduces light reflections off the surfaces of the glass, the average is only 1-2%. This means that 98-99% of the light striking the filter is going through it, and depending on the type of filter, into the camera lens and onto the film. These layers of anti-reflective coating are bonded to the surface of the glass in a furnace at a temperature of up to 800 degrees F.

Why a Hoya Multi-Coated Filter™
The wide aperture lenses of today are very expensive and all photographers want to get the most speed, optical performance, and dollar performance from their investment.

Say a customer pays $500.00 for a 28-70mm f/2.8 lens. Then, to protect this investment the customer buys a cheap bare glass filter, which has a light reflection rate of 9%. This filter is literally slowing the lens down by 9%, or effectively turning a $500 f/2.8 lens into the equivalent of a slower f/3.0 lens worth $455. The value of the lens drops 9% when you put the cheap filter on it. The cost savings of the less expensive filter do not off set the loss of lens speed.

Also, this does not address the loss of sharpness or focus shift, which can have a noticeable detrimental impact on picture quality. For these reasons, Hoya multi-coated filters present the best value on the market today.