French photographer and YouTube creator Mathieu Stern’s latest video discusses the wonderful world of close-up lens filters. Unlike some of Stern’s stranger topics, like working with the world’s blackest material and capturing travel photos with an infrared digital camera, close-up filters are something nearly every photographer might want to add to their kit.
Close-up filters, sometimes called diopters because their strengths are measured in diopters (like corrective lenses for eyes), are mechanically very simple. They act as a magnifying glass photographers can screw onto the end of their lens, effectively reducing the minimum focusing distance of a given lens and enabling photographers to get closer to their subject. Close-up lens filters are almost always significantly cheaper and easier to use than a dedicated macro lens.
Stern’s video breaks down the benefits of different strength close-up (diopter) filters using a 75mm prime lens. Close-up filters come in varying strengths, typically ranging from 1/4 to something like plus two or four. However, greater strengths are also available, up to as much as +10. Depending on the standard close-focusing distance of a lens, a plus-two close-up filter can get you near or in macro (1:1 or 1:2) territory.
This all sounds fantastic so far, but there are downsides. Whenever a photographer puts an additional piece of glass on the end of their lens, it will have some impact on image quality. Generally speaking, the more expensive a filter, the less the image quality cost because the filter has higher-quality materials and sophisticated optical coatings.
Stern has a wide array of close-up filters, including one he picked up for around a dollar at a yard sale and a high-end one from Schneider-Kreuznach that costs up to $400 per filter. Quality glass is never cheap, and that applies to close-up filters as well.
Potential downsides to using cheap ones, like the $10-20 kits available on Amazon, are loss of contrast, excessive flare, inaccurate color, and reduced sharpness. However, as Stern demonstrates, there are ways to mitigate image quality loss, including stopping down the lens aperture and utilizing good technique.
While close-up lens filters are an affordable and often effective alternative to a dedicated macro lens — or a means of making a macro lens even better — they are also beneficial for cinematographers using anamorphic lenses. Anamorphic lenses are all the rage in video these days, thanks to their unique look. However, many struggle with close-up performance, delivering long minimum focusing distances. Many cinema-oriented lenses have huge front diameters, something Schneider-Kreuznach clearly considered with its close-up filters, which come in 138mm sizes.
Mathieu Stern makes a strong case for close-up lens filters or diopters. They can be an inexpensive and very accessible way to get into close-up and macro photography. They can also make a photographer’s or filmmaker’s favorite lenses more versatile.
Image credits: Mathieu Stern
