Should I buy a camera without a low-pass (anti-aliasing) filter?

June 16, 2014 at 10:30 am  •  Posted in News & Events, Q&A, Tips & Techniques by

I just started researching Nikon DSLRs before actually shopping for one, and I noticed that the D3300, D5300, D7100 and D800E omit an optical low-pass (OLP) filter. Apparently this is supposed to produce better resolution but at the risk of something called moiré which can create some type of problem. What’s the bottom line on this technology?
—Anita S.

A few other cameras (from Fujifilm, Olympus, Leica, Sony and Pentax, as well as the new Nikon D810 announced this week) also omit the OLP filter, Anita. This component over the imaging sensor—also called an anti-aliasing filter—is intended to eliminate moiré pattern and aliasing (color artefacts). It’s difficult to describe moiré, but you can see an example in the photo provided by PhaseOne further down. It occurs when a finely patterned subject—such as certain types of fabrics—conflicts with the commonly-used Bayer Pattern sensor’s pixel grid.

june Low-Pass Nikon

As this diagram illustrates, a low-pass filter separates the light that will strike the sensor in four segments in order to eliminate moiré pattern. When the OLP filter is omitted or deactivated, the light is transmitted without separation to maintain maximum resolution. Photos Courtesy of Nikon.

Until recently, the low-pass filter was standard because it can eliminate the moiré pattern in the few situations where it occurs. However, the OLP filter also blurs intricate detail at the pixel level, reducing the effective resolution, as you mentioned. In truth, the blurring is minimal, and its effect can virtually be eliminated with extra in-camera sharpening. You can find examples in a test report on the Digital Photography Review website, which provides photos made with the D800 versus the D800E on their image-quality comparison pages.

You can also get a lot of technical information on Moiré & False Color on Nikon’s website, as well as shooting tips to minimize the problem with cameras that omit the OLP filter. As the article confirms, it’s easy to eliminate moiré if you shoot in the RAW capture mode and use converter software such as Nikon Capture NX2, PhaseOne Capture 1 or certain Adobe programs. If you shoot JPEGs, however, it’s much more difficult to correct for moiré pattern because the photos are fully processed in the camera. Check out this video tutorial: Adobe Photoshop Eliminating the Moiré Effect for more examples of moiré and how to remove it from photos made with JPEG capture.

These photos from PhaseOne provide a visual indication of moiré pattern and confirm that it can be quickly and easily eliminated with software if the photos are in RAW format. Frankly, this effect rarely occurs, and that's why some cameras now omit the OLP filter in order to provide maximum resolution. Photos Courtesy of PhaseOne.

These photos from PhaseOne provide a visual indication of moiré pattern and confirm that it can be quickly and easily eliminated with software if the photos are in RAW format. Frankly, this effect rarely occurs, and that’s why some cameras now omit the OLP filter in order to provide maximum resolution. Photos Courtesy of PhaseOne.

So, what’s my recommendation? Buy the camera with the features that best meet your needs, whether it’s equipped with the OLP filter or not. If it is not, you’ll get maximum per-pixel sharpness (crispness), although frankly, that benefit is small as confirmed by the examples on the Digital Photography Review website. Yes, that type of camera will increase the risk of moiré pattern if you often photograph the few types of subjects that can create the effect. However, I have owned a Nikon D7100 for about a year and have yet to encounter the problem, so I no longer worry about it.