Diopters "Filters"

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The below photos taken with various  diopter combiniations using a Konica-Minolta DiMAGE A2 point & shoot to give an idea of magnification.

Please mouse click photos to view full size.

diop3	diop4	diop5	diop6
diop7	diop8	diop9	diop99

 What is a diopter? Diopters are basically magnifying glasses, sometimes called macro conversion lenses. They increase magnification because they allow you to move closer to your subject when focusing. Sometimes sold as close up filters, or macro adapters with most common sizes up to a +10 diopter.

Numerous brands of diopters are available, and over the years I've tried a large variety. Quality of glass, and coating can vary drastically.

My favorites are the double element design produced by Canon, though other double element disigns are produced by Nikon, and after market makers such as Raynox.

The primary advantage of diopters over extension tubes being diopters work with point & shoot cameras, as well as D/Slr. And since they screw into the filter thread of your lenses, the exposure does not require compensation, but amount of magnification will vary depending on lens size used.

I suggest purchasing the best possible quality you can, but this depends greatly on your circustance and intended use. While some diopters can cost over $2000.00, but sets of three can be found for around $50.00 US, for those wishing to experiment.

Diopters are rated by strength, with higher numbers giving more magnification but less working distance. The double element designs can cost up to four times more than single elements, but are they really worth the price?

For comparison, lets check a Canon 500D next to a less expensive Hoya +4 single. The target is a 4 inch card, with camera mounted to a copy stand, distance to card is the same for both photos. Light is two, 100watt bulbs. You can see the 500D is sharper in the corners, exibits less distortion and less fringing. The Hoya gives slightly more magnification, even at this distance.

However, these are manufactured for close up use, and results under controlled conditions show less difference. The next comparison is at closest focus distance, camera color balance unchanged from first comparison.

If you intend to photograph coin collections inside, less expensive diopters may be all you need. But if you intend to photograph insects in bright sunlight outside, fringing and flare can become a problem with less expensive models. In this case, double element would be the way to go if using a Point & Shoot, but DSLR owners need to decide how often they'll use one. And since cost of double element design can be more than some extension tubes, I'll leave the decision to you.  

Diopter magnification increase varies according to lens used.

Note: The Canon 250D is specific for lenses up to 70mm, and roughly equals a +4 diopter. The Canon 500D is designed to use with 70 to 300mm lenses, and is roughly a +2 diopter when used with longer lengths.  The Canon diopter without the "D" designation is a single element diopter costing somewhat less, but maintains quality coatings. For specifics on other brands, check place of purchase or makers web site for details.

If possible, purchase over sized diopters and use a "step down ring" to fit smaller filter sizes, this will help minimize distortion and allow using them with a larger variety of lenses. The example shots are using 52mm diopters, stepped down to the 49mm thread of the A2.

Other Filters:

For other types of filters, step down rings are also useful. An example would be using one for your circular polarizer since CPL's can be expensive. Other filters such as UV Haze are generally considered "protective" against lens scratches, and left on each lens most all the time. My concern is they usually cause reflections in night shots, especially since many purchase less expensive filters for this purpose.  

Star Filters are ones I find little use for. You can get a star effect by stopping down your aperture. For nightscapes which include lights, use a tripod and close your f/stop to f/11, going too far beyond might cause lens distortion as discussed in the Getting Started section. The number of star points you'll have is determined by the number of  diaphragm blades in the lens.

Nuetral Density or ND, are helpful when you need to use slower shutter speeds when photographing water scenes to show a flowing effect. ND's are also available in "gradutated" to help darken the sky. And while it's common to see photos with water showing movement, consider using the effect when shooting landscapes on windy days. Tall grass movement can add a painted affect to your photograph which is seldom seen. Of course, the same affects can usually be done by lowering ISO, and closing your aperture. But if you find you're stopping down excessively, an ND is the answer.

There's also numerous other Special effect filters available. Check online using Google, or your local pro camera store for additional information.

Brand names are registered trademarks of their respective owners and used for discussion purpose only.