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Brian Tobey
Nikon D800E FX

NIKON D800E

NO AA VERSION | FEBRUARY 7th 2012 | PRICE $3299

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PROSCONS
Detailed Imagery
Enhanced Autofocus
No Anti-Aliasing
SECTION SUMMARY
PRE-ORDER D800E D800

Last Updated: February 16, 2012 | By Brian Tobey Email Google+

SUMMARY


INTRODUCTION:

Nikon D800E

The Nikon D800E features the same specifications of the Nikon D800, but with the anti-aliasing filter removed. The D800E also comes at a higher price. This means you pay more for less? Well not exactly. It is not as if you could purchase a D800 and remove the AA filter yourself. The filter is a manufactured with the UV and IR filter. In the D800E, Nikon replaced the AA filter feature with a simple low-pass filter instead, to prevent the softening effects of the anti-aliasing filter.

A lot of questions arise with having two models for one camera. This article only addresses the concerns of the Nikon D800E. If you are looking for more information on the Nikon D800, see the Nikon D800 Review. Nikon has officially announced the Nikon D800 and D800E on February 7th, 2012, and the D800E is expected to be available in early April.

NOTE: This article only describes the affects of color moire on the D800E and artifacts that may occur due to the lack of anti-aliasing filter.

CLARIFICATIONS ABOUT COLOR MOIRE

There appears some confusion about how color moiré affects the D800E. Here are some things you ought to know:

  • Color moiré is produced from the spatial domain (3D) translation to the image domain (2D) and cannot be 100% corrected in post processing.
  • Color moiré patterns occur on a pixel level and are part of the demosaicing process of the bayer grid sensor
  • The D800E has a different filter than the D800, without an anti-aliasing function

SOFTWARE REDUCTION

Moiré can be reduced in software, but not without consequences. Nikon's updated Capture NX to provide moire reduction, and the upcoming Lightroom 4 will have a color moire reduction slider when using the brush tool. However, most software techniques to reduce moire are far from perfect and can cause addtional degredation in quality. When using the D800E it is best to try to avoid taking pictures that are suseptable to moire.


ANTI-ALIASING FILTER

Below is a simulated bayer photo site arrangement to show the basics of how color moiré occurs. Each pixel on a bayer sensor is made up of four photo sites to determine color, red, green, blue, and green again. Why green twice? Because it requires four to complete the square and green is preferred.

Now, if we were to photograph something back and white that repeats and is fine enough to cuts through a pixel halfway when rendered through the lens, then the resulting pixel will show color, because only some of the RGB photo sites are exposed by the black and white lines.

The 3rd row shows this overlayed on top of the bayer color grid. The final row shows the resulting interpreted image.


Nikon D800E Moire Simulation

Moire Example

The purpose of the anti-aliasing filter (AA) is to reduce the effects of color Moiré patterns that occur from a Bayer sensor. Moiré patterns are derived from aliasing. Aliasing occurs because a signal is under sampled or sampled below the Nyquist rate. What does this mean in photography terms? Aliasing can occur when you attempt to capture something of greater detail than can actually be digitally resolved. However note that aliasing can occur more often in Bayer type sensors because of the way the photo sites are arranged by color. This kind of aliasing is related to color and is responsible for color moiré patterns. It is the main reason why camera manufactures that use Bayer type sensors, like Nikon and Canon, add anti-aliasing filters. These anti-aliasing filters generally reduce image sharpness.

Also note that there are two forms of aliasing commonly discussed in photography: color aliasing and luminescent aliasing, where color aliasing is most commonly caused by the Bayer color arrangement, which is the topic of concern for the D800E.

GENERAL ALIASING CONCEPT AND NYQUIST

In general, think of aliasing as interference of details that are too fine for the sensor to resolve.

Now the D800E still has a optical low pass filter (OLPF) to prevent any of this general luminescent (black/white) aliasing from occuring.

For example, consider a brick wall from a far distance. If each brick is smaller than an individual pixel in your camera, then your camera will not resolve the information. However, a new pattern will be rendered based on the unresolved detail. So instead of seeing bricks, you may see horizontal stripes. This can also occur in cityscapes where the building windows are small and grid like.

Shown below is a simple stripped black and white pattern. Now pretend this pattern is on a wall and you take a picture of it from a good distance. The second plot simulates how it may be rendered through a real world optical lens with some imperfections. Now the plot bleow that shows a sinusoidal pattern describing the contrasting frequency of the black and white pattern. The red Xs demonstrate sampling or where pixels may be positioned on a sensor. In this example, the pixels are undersampled below the required nyquist rate to adequately discern and reproduce the actual black and white pattern. The bottom plot shows the output and what would be recorded as the image.

Now if the data was filtered using an anti-aliasing low-pass filter before it was samples (red X's), then it would produce a more even gray across the entire pixel grid. Using this filter would produce a more realistic appearance of what we typically see with our eyes, as oppose to this new pattern caused by undersampling without a filter.

Consider a person with a black and white checkered shirt on. Now picture that same person in the far distance, the shirt may average out to be form a grayish color, seen by our eyes. This is partly because our eyes do not sample discretely, like the digital cameras do, and are instead more continuous.

Moire Example

NIKON D800 VS D800E DIFFERENCES

The figure to the right is a conceptual depiction of how I suspect the difference in filter implementation of the D800 and D800E. These filters are placed just before the sensor. The filters group is composed of UV and IR band reject filters, and low pass filters to prevent aliasing.

For the standard D800, the light is split horizontally (polarize), then filtered (low-pass), then filtered for IR, and then split vertically and then filtered again to prevent color moiré. The D800E is similar, except that it is not split in two axis and filtered twice, instead it is only split once and filtered using one low pass filter. This allows color moiré to still occur but provides less blur caused by the low pass filters.

Although this provides a brief summary, it does not provide us with any conclusion. Unless we are given the low pass cut off frequency specs, and its relation to the bayer RGB photosite arrangement and size, only then can we fully understand the true impact of the two filters have on image results. I hope to perform some extensive testing whne I receive the cameras.


EXISTING CONCEPTS

Nikon is not the first to come up with a non anti-alias filter camera. The larger format, Pentax 645D does not have an anti-aliasing filter and features a 40MP sensor. LEICA does not use an AA filter in their full frame M9. The foveon sensors that Sigma produces do not use a bayer sensor like most camera manufacturers, therefore they do not exhibit color moiré patterns and do not use anti-aliasing filter.

Anti Alias Camera Comparison

NIKON D800 IMAGE SAMPLES

Rob Van Petten provides an in depth preview of the amazing capabily this camera has. He provides sample images on his website.

Also additional samples can be found on Cliff Mautner's site here. Also some high ISO samples.

Currently, the best D800E samples can be found straight from Nikon's website.

CP PLUS 2012 - HANDS ON PREVIEW



CONCLUSION



The Nikon D800E model provides the resolution required for serious high resolution photography. When photographing, it is important to know where color moire can occur. Only until we can compare the two models, will we be able to discern the major benefits of the anti-aliasing filter removed for the D800E. For most users, I would stick with the base D800.


PREORDER NIKON D800

Amazon is no longer accepting orders. You can be notified of when the D800 will become available: Nikon D800 and Nikon D800E.





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