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Thread: What is the diff over Hoya HMC (0),(N) & Guard?

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    Default What is the diff over Hoya HMC (0),(N) & Guard?

    I noticed that Hoya has different type of HMC UV filter, what is the main difference or purpose?

  2. #2
    Senior Member yyD70S's Avatar
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    Default Re: What is the diff over Hoya HMC (0),(N) & Guard?

    Price.

    And ... number of coatings.

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    Member smtan24's Avatar
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    Default Re: What is the diff over Hoya HMC (0),(N) & Guard?

    Quote Originally Posted by sti2300
    I noticed that Hoya has different type of HMC UV filter, what is the main difference or purpose?
    The following taken from Hoya represtative webpage.

    Hoya Coating and Multi-coating, the quality difference.

    Hoya manufactures a full line of filters in both standard and Hoya multi-coated. The difference between Hoya’s standard line and that of other manufacturers is that Hoya standard filters have one layer of anti-reflective coating applied to each surface of the glass. Many other manufacturers standard filters are bare glass, and bare glass can reflect as much as 9% of the light hitting it. This greatly increases the risks of flare and ghosting.



    This can be seen in a simple test. Take a bare glass filter hold it so that light reflection off the surface can be seen. Then take a long very thin object like a pin or the tip of a pen and hold it over the filter so that its reflection can be seen. There will actually be two reflections of the pin on the surface, one a little more pronounced than the other. The more pronounced reflection is from the front surface and the lighter one is from light reflecting off the rear surface.

    Hoya’s single layer coating decreases light reflection off the surface from approx. 9% to an average of 4-5%.



    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.



    You should beware! Some other manufacturers claim to have “coated” filters. But this coating is often only applied to the front side of the glass, not both sides like Hoya filters. Also, the coating on many filters is “painted” on or applied as a cold spray that wares off easily.

    Best of the Best

    In 1996 Hoya introduced the line of Super Multi-coated filters. Consisting of a Skylight, 1B, UV (0), ND 2X, ND4X, and a low profile circular polarizer, this line of filters has a 5+1 layering system on each side of the glass: 5 layers of anti-reflective coating and a transparent easy-clean top coat. This reduces light reflections off the filter surface to an average of just 0.3%. This is the lowest reflective rate on the market, from any filter manufacturer.

    Lastly, how is the glass itself made? How do filters get their color? Some manufacturers simply take two thin sheets of regular glass and sandwich a colored gel or glue in between, as shown in the previous diagram. This process is called lamination. It is a very cost-effective process but not a high quality one. Remember, the disadvantage of this process is that over time the different materials can separate, causing bubbling or pealing (referred to as delamination,) rendering the filter useless.

    Also the thin gel used can shift its color so that the filter does not yield the same color rendition over time. The last drawback of this process is that all 6 surfaces of the three layers have to be perfectly flat and parallel. If they are not, the filter will have a “lens effect” which can greatly reduce image quality.

    To insure consistency in glass manufacturing, Hoya uses a furnace called an Automatic V blender to mix the different materials at a highly controlled rate. This process creates glass that is pigmented all the way through. With pigmented glass there is no chance shifting over time. There is also no chance of delamination. Also, the two surfaces of the glass are ground and polished for perfect flatness.

    The only exceptions are Polarizer and Circular Polarizer filters. No matter the brand or quality, they all are made of a polarizing film, or a polarizing film and quarter wave plate in the case of the Circular Polarizer, sandwiched between two layers of glass.

    Hoya believes the filter frame is an extremely important part of the filter as well. Hoya uses 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 the polycarbonates 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. 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 Value in 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.

  4. #4

    Default Re: What is the diff over Hoya HMC (0),(N) & Guard?

    What I wish to know is does (N) , (0) & Guard mean? They are all HMC (Multi Coated)

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    Member smtan24's Avatar
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    Default Re: What is the diff over Hoya HMC (0),(N) & Guard?

    Quote Originally Posted by sti2300
    What I wish to know is does (N) , (0) & Guard mean? They are all HMC (Multi Coated)
    This is what I got off the web hope it answers your question:

    There are 2 different UV from HOYA - UV(N) & UV(0). AFAIK, UV(N) has been marketed in Asia only because it has inferior glass quality, and much cheaper than UV(0). UV(0) uses the same high quality glass as other high quality filters. And yes, both are available in HMC, and the situation is confusion.

  6. #6

    Default Re: What is the diff over Hoya HMC (0),(N) & Guard?

    OK, Thanks.

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    Member smtan24's Avatar
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    Default Re: What is the diff over Hoya HMC (0),(N) & Guard?

    You're welcome.

  8. #8

    Default Re: What is the diff over Hoya HMC (0),(N) & Guard?

    Quote Originally Posted by smtan24
    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.
    is this really true?
    means if you are using cheap filter, your exposure will be wrong?

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    Default Re: What is the diff over Hoya HMC (0),(N) & Guard?

    Quote Originally Posted by popeye
    is this really true?
    means if you are using cheap filter, your exposure will be wrong?
    No. in SLR camera, exposure measured after the filter and lens, the light intensity falling to the sensor inside camera body. So, say if the filter is only 50% transmit the light (and 50% reflected), your exposure still correct.

    I think smtan try to say, don't degrade your lens further by using cheap filter.

    Regards,
    Arto.

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