Should You Buy a Camera Without a Low-Pass Filter?

by Peter K. Burian

Low-Pass Nikon
Low-Pass Nikon
© Peter K. Burian
All Rights Reserved
Question: 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" (anti-aliasing) 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?

Answer from Peter Burian: few other cameras (from Fujifilm, Olympus, Leica, Sony and Pentax -- as well as the brand-new Nikon D810) also omit the optical low-pass (OLP) filter. 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.

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

PhaseOne Moiré
PhaseOne Moiré
© Peter K. Burian
All Rights Reserved
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 had 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 DP Review Web site which provides photos made with the D800 vs. the D800E on their image quality comparison pages.

You can also get a lot of technical information in Moiré & False Color on Nikon's Web site 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.


PHOTO CAPTION: These PhaseOne images 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 DP Review Web site. 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.


Learn more about photography...

Peter Burian teaches three interactive online courses at BetterPhoto's digital photography school:
-Mastering the Digital Camera and Photography
-Boot Camp for New Digital SLR Owners
-Mastering the Canon EOS Digital Rebels


Also, Peter's photography appears in these two books: The BetterPhoto Guide to Creative Digital Photography and The BetterPhoto Guide to Photographing Light.



Article by Peter K. Burian. To learn more about photography, explore the many online photography and Photoshop classes offered here at BetterPhoto.com.