Is My Filter Multi-Coated?

Here are a few things to watch out for when purchasing filters:

1. Mono Coated or Standard Coated filters (sometimes referred to as Double Coated) sold as Multi-Coated
    I have on numerous occasions seen Mono Coated filters being advertised as Multi-Coated. They are NOT Multi-Coated.
A single layer of coating is applied to the front and rear surface. This does NOT make the filter multi-coated. This is really getting out of hand.  I recently looked on one of the auction webs and found over a hundred standard mono coated filters being offered by the same seller,  having Multi Coated in the title.  This is bad for legitimate dealers. When buyers purchase what they are lead to believe is a multi-coated filter, they are then disappointed in the filter's performance.  Would they buy a multi- coated filter again, if they saw no improvement over the filter they replaced?  I don't think so.

A multi-coated filter has several layers of coating applied to one or both surfaces of the glass depending on the type of filter. Manufacturers have gone to great lengths to develop superior multi-coatings and are quick to let you know about them. The box will say MULTI-COATED on it if it is a multi-coated filter. The filter ring will also indicate if it is multi-coated. Sometimes it may only have "MC" stamped on the ring which   is dictated by the manufacturer.  If you have any doubts that your filter is multi-coated, it most likely is not. Multi-coating is very easy to see. Upon close examination of the filter; you will be able to discern several different colors: green, yellow and blue being the most common. The easiest way to check for multi coating is to get the reflection of a household light bulb in the filter. If the filter is multi coated the bulbs reflection will be radically changed.

2. Special Effect filters being sold as Coated
   Star Filters, Diffusion Filters,  and most special effect filters are NOT coated.   A coating applied to these filters would actually impair the intended effects the filters were designed to make.  Don't pay more for a special effects filter, because you are being told it is a coated filter. It is not coated.