Anti Aliasing / Low Pass filter removal for sharper more detailed images

As many of you already know Nikon has released a special edition D800E version of its super high 36 megapixel resolution D800 camera body. Essentially the two cameras are identical in every way except the lack of the AA filter or Anti Aliasing filter in the D800E along with a higher price tag.
Why the missing AA filter you ask? Well, two reasons, sharper images and more captured fine detail in those images. This may be a great feature for studio and landscape photographers who may not mind the occasional occurrence of moire in SOME images while getting more sharpness and detail in EVERY image.

The bellow images and original ePHOTOzine article can be viewed by clicking the images bellow.


Stay tuned as we will be adding comparison images from various cameras we modify for our customers.

What about that moire? Pretty much every image post processing software now includes moire removal tools making it quite simple to remove in post processing (must capture in RAW). You could even batch process the images in a few of them to remove moire.

So why wasn’t this option available before? It was. In fact it wasn’t an option at all but a standard feature in most medium camera digital backs for the last decade. DSLRs have never had the kinds of resolutions that medium format shooters were able to enjoy until recently and so moire would be too frequent in their photos.

To understand why DSLRs were more prone to moire and why anti aliasing/low pass filters were necessary you must understand what causes moire. Moire occurs when 2 or more patterns (like chain link fencing or striped shirts) that are close to the same frequency or pitch (think size of fence grid or shirt stripes spacing) interfere with one another causing patterns to appear that are not really there. Perhaps you have driven by a property with chain-link fencing where you could see the fencing on the back end of the property through the front side fencing and noticed changing patterns appear as you drove by, well, that’s moire.

In digital cameras this occurs through the interaction of repeating patterns in the subject and the regular, repeating pattern of digital camera sensor pixels. When both are close to the same size or pitch/frequency, poof, you have moire. To prevent this camera manufacturers place an optical filter in the light path between the lens and imaging sensor to slightly blur the sharpness/fine detail (high pitch) that is similar in frequency to the sensor. This effectively prevents moire but at the expense of the full resolution and sharpness possible from the sensor.

Yes, but why were DSLRs more prone to moire than medium format digital backs? Simply because MF digital backs had much more resolution much earlier in their evolution than did DSLRs. DSLRs are only now catching up to the resolutions that were available years ago in medium format backs. For example, the Nikon D800 which has a 36mp sensor was released this year while the Hasselblad H3D 39mp back was released in 2006, that’s 6 years ago!

Why aren’t more DSLR makers making cameras without AA filters? Who knows, perhaps because moire is still possible and their target market may find it objectionable enough to affect photographer purchasing decisions. Perhaps because the competition isn’t either and they don’t want to venture out on their own. Looks like Nikon took the first step here, let’s hope more manufacturers in the future will follow suit and at least offer photographers a choice.

Can the AA filter / Anti-aliasing filter be removed from my DSLR camera? Absolutely. Since the release of the Nikon D800E we have been inundated with requests for AA removal modification. You can order the AA removal service on our website here.

Aside from the moire is there anything else to be aware of before removing the AA filter? Because the AA filter is a physically glued part of the low pass filter stack, removing it would also remove the infrared blocking filter. This would cause your now very sharp, detailed images to be contaminated with infrared light. In order to prevent this we replace the low pass filter stack with our own custom infrared blocking filter. This change could potentially shift the white balance a bit but this minor issue can easily be corrected with a custom white balance preset in camera or in post processing.

Can the AA filter be removed from my infrared, full spectrum, UV or H-Alpha camera? Glad you asked, since it’s in the stack along with the infrared filter it has already been removed.

Here are some interesting comparisons between the D800/D800E:
http://www.luminous-landscape.com/reviews/cameras/nikon_d800_d800e_first_comparison.shtml
http://www.ephotozine.com/article/nikon-d800-vs-d800e-digital-slr-review-19764
http://www.ephotozine.com/article/nikon-d800-d800e-digital-slr-hands-on-review-18420
http://kenrockwell.com/nikon/d800/vs-d800e.htm

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