Shoppers Guide to Camera Filters

Today’s Post by Joe Farace

Camera filters are available in lots of different different shapes, sizes and materials including delicate gelatin filters that drop into holders or lens hoods, glass filters that screw onto your lenses and rectangular filters that fit modular holders.

Gelatin filters are made by dissolving organic dye in liquid gelatin, which after drying is cut into square or rectangular shapes. The most popular size is 3×3 inches, although they’re available up to 14×18. Gel filters are only 0.1mm thick, and offer excellent optical quality but are fragile. You can tape gel filters to the front of a lens but they’ll last longer if you use them in a holder. For more, see my riff on Wratten Filters.

Gels used to be inexpensive but now a filter such as Kodak’s 3 x 3″ Neutral Density (ND) gelatin filter is $89.95. True filter hounds always check the junk boxes of photo swap meets where gel filters can often be found for a few bucks.

Some glass filters are constructed by sandwiching a gelatin filter between two sheets of glass. Over time, these materials separate, causing bubbling and peeling. An alternative is dying the glass when it’s in a molten state, which  means there’s no color shifts as the filter ages. All polarizers are laminated because they use polarizing film to make the filter do what it’s supposed to do.

How well a filter ring is made should be obvious from just picking it up, twirling it in your fingers, and screwing it onto a lens. Heliopan and B+W mount their filters in brass because it l won’t bind or cross thread. Hoya uses aluminum because it absorbs shock in case of accidental impact.

In Jurassic times camera manufacturers kept filter thread sizes of their lenses consistent between different focal length lenses but nowadays they don’t seem to let that get in the way of a new lens design. What this means is that you might need several sizes of the same filter to fit your different lenses. With modular filter systems you only need one filter along with a holder and adapters for different lens threads. Filters for Cokin’s “A” size measures 75x75mm while the larger “P” size is 84x84mm. An adapter lets you use “A” filters in “P” holders. Cokin may have popularized the modular concept but similar systems are available from other companies including Hitech  and Lee.

How I made this shot: Some cameras, such as my beloved Olympus E-P3 that was used to make the photo above have internal SFX (not physical) filters that are built into their firmware. Lens used was the Olympus M.14-42mm F3.5-5.6 II R kit lens (at 33mm) with an exposure of 1/200 sec at f/9 and ISO 200.


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