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A preview of the Nikon D2H - Continued

In keeping with the news and sports photographer focus of this camera, Nikon opted for almost the identical balance of resolution and file size as Canon did in designing the EOS-1D, to ensure the D2H would record files that can be transmitted quickly and otherwise be workflow-friendly for the photographer working in the field, while still providing sufficient enlargeability and croppability for a broad range of newspaper and sports magazine uses.

In fact, except for a slight difference in the proportions of the frame, the width and height in pixels of the full-resolution photos from each camera are effectively the same. Nikon seems to have resisted the urge to one-up Canon on the spec sheet, in exchange for a file size that should be near-ideal for the photographer at which the D2H is aimed. In short, 4 million pixels is what we wanted from a replacement for the D1H, and 4 million pixels is what we got.

In our briefings on the D2H, however, Nikon has gone to great lengths to emphasize that not all pixels are created equal.  Promised is a lack of noise, impressive photographic smoothness and a level of clarity in D2H files that belies their modest 4MP origin. And the large Epson 2200 prints from early D2H cameras we've been shown, which were primarily long lens shots taken in beautiful light, as well as some higher-ISO D2H files that have been shared with us surreptitiously, seem to support the contention that D2H photos will have oodles of detail and not too much noise.

Ultimately, discussions of D2H image quality at this point ought to be about what's possible and not what's real, since the camera isn't done. But we can't wait to see what Nikon has been able to achieve when files from the D2H begin to emerge for real a bit later this year.

This section looks at the image sensor, image processing features and image processing options of the D2H.

LBCAST, JFET, FPN, BPD and more

An alphabet soup of digital nomenclature is required to describe the image sensor in the D2H. The 4.26MP sensor is neither CMOS (Complementary Metal Oxide Semiconductor) nor CCD (Charge Coupled Device), it's LBCAST (Lateral Buried Charge Accumulator and Sensing Transistor).

nikon_d2h_LBCAST.jpg

The Nikon-designed sensor, which is approximately (but not exactly) the same physical size as the CCD sensor found in the D1H and D1X, features JFET (Junction Field Effect Transistor), BPD (Buried Photo Diode) and internal FPN (Fixed Pattern Noise) suppression technology, all of which is meant to contribute to the D2H's promised low-noise characteristics in both low ISO and high ISO frames as well as during long exposures. It features CMOS-like dual-channel data readout for quick refresh of the sensor in support of the D2H's 8 fps shooting rate, ultra-low power consumption and a structure that places the sensor's microlenses closer to the light-sensing photo diode within each pixel for improved consistency from the centre of the sensor to the edge.

All this technological gobbledygook, says Nikon, should add up to a sensor capable of passing on clean data to the all-new image processing circuitry of the D2H. Other core image sensor and image processing features include:

  • The sensor's 4.26 million total pixels are crunched out to 4.02 million final image pixels after some edge pixels are discarded. Image dimensions on the [L] resolution setting are 2464 x 1632 pixels; with the camera set to [M] resolution, 1840 x 1224 pixels. The lower resolution setting is achieved by resampling the full-resolution sensor data in the camera during processing, as opposed to the sensor itself offering multiple resolutions.

  • [L] resolution files open into Photoshop as 11.5MB 8-bits per colour, or 23MB 16-bits per colour, photos, depending on the file format chosen in the camera. [M] resolution files open into Photoshop as 6.44MB 8-bits per colour photos.

  • The sensor utilizes a traditional bayer pattern RGB filter array over its grid of pixels.

  • 12-bits per colour image capture. RAW NEF retain the full 12-bits per colour of data; JPEG and TIFF files are converted to 8-bits per colour during in-camera processing.

  • A thinner optical low-pass filter made of lithium niobate is sandwiched in front of the LBCAST sensor. By thinner Nikon appears to mean, in part, that it has reduced the blurring strength of the filter as part of its strategy to eek out as much detail as possible from the new sensor. This certainly appears to be the case in the small number of D2H photos we've examined. By comparison, we've observed that with all previous Nikon digital SLR cameras, Nikon has been prepared to go with a slightly heavier-duty low-pass filter that foresakes some detail, in exchange for minimal moiré and colour artifacting (which low-pass filters are designed to catch). When we looked at the blurring strength of the low-pass filters in Canon's EOS-1D, EOS-1Ds and EOS D60 for a project last year, we could plainly see that Canon chose a different balance of detail and artifacting/moiré in each camera, even when we factored in the differing resolutions of each model. The D60 leaned towards minimal artifacting but slightly reduced detail, the 1D towards maximizing detail but with a tendency to show both both artifacting and moiré, while the 1Ds landed between the two models. In designing the D2H, Nikon seems to have opted for the 1D approach, though with an emphasis on post-capture colour processing to beat back any colour artifacting. They also promise that the D2H's low-pass filter design will also be effective at reducing moiré.

Note: A Nikon technology primer further explains the role of an optical low-pass filter in a digital camera.

  • One of the biggest advantages of the LBCAST sensor that Nikon is touting is the lack of dark current noise in longer exposures. That is, even without noise reduction, the sensor exhibits less of the type of noise that accumulates in any sensor when exposures are measured in seconds or even minutes. In addition, new real-time noise reduction is automatically activated whenever the shutter is open longer than 1 second; there is no processing delay with this form of noise reduction. Also an option in the D2H is traditional long exposure noise reduction, a feature found in Nikon's SLR lineup only in the D100 currently. When enabled, the camera records a second, dark frame internally after the picture is taken, then uses that frame as a mask to diminish the noise spots in the actual picture.

  • Part of Nikon's emphasis on their efforts to stomp out sensor noise undoubtedly stems from the fact that the D2H's LBCAST sensor is about the same physical size as the CCD in the D1H. Standardizing on the DX-size sensor across its digital SLR lineup means that to increase the resolution of the D2H relative to its predecessor, Nikon had to make each pixel smaller. In general terms, smaller pixel sensors have lower signal-to-noise ratios than larger pixel sensors, which can translate into noisier photographs. What Nikon is emphasizing, then, is that despite its smaller pixel dimensions - 9.4µm square for the D2H vs 11.9µm square for the D1H - the light-gathering efficiency of the D2H's newly-minted sensor, its overall low-noise characteristics plus new real-time noise reduction through the image processing path will mean that D2H photos will contain less noise, not more, than those from the D1H at a given ISO. If true, this will be an impressive feat.

  • Nikon is further emphasizing that an all-new hardware processing circuit (ASIC, or Application-Specific Integrated Circuit) reduces colour artifacts while smoothing out jaggies on oblique lines.

In short, the combination of the D2H's sensor and image processing is promised to add up to "image quality that surpasses every camera in its class, " says a Nikon USA press release.

File formats

There are two changes of note:

First is the D2H's ability to record both RAW NEF and JPEG files for each frame simultaneously. This feature in Canon's EOS-1D has always been of limited use for us because of that camera's relatively skinny buffer (relative to its high frame rate). In the first few real world situations in which we attempted to shoot RAW+JPEG at 8 fps, we ran out of bullets too soon, then had to wait too long as the 1D cleared photos to the card.

The larger buffer of the D2H could make all the difference in bringing this feature to life, though we're unclear as to what the actual burst depth will be when the camera is set to record both file formats for each trip of the shutter (it will probably be closer to 25 frames than 40). There will also be an additional benefit to using the dual-format setting, since the D2H can be configured to transmit just the JPEG over the optional WT-1 transmitter when the camera is recording both RAW and JPEG simultaneously. For those photographers who see a benefit to having the RAW file for higher-quality downstream uses, or to fix white balance or other errors after the fact, but who also need to a get a picture transmitted right now, the RAW NEF and JPEG option should be ideal.

Second, Nikon has made the compressed RAW NEF setting a viable option in the D2H, by performing the compression in a speedy dedicated hardware circuit. In all other Nikon digital SLRs, the camera's main microprocessor is responsible for performing the compression. The D100, for example, requires a full 35 seconds to compress one photo, which is too slow to be considered practical. In the D2H, the compression happens in near-real time.

This should make it feasible to choose the compressed RAW NEF setting and gain the benefits of having 50-60% smaller files written to the CompactFlash card. As with previous Nikon digital SLR models, Nikon describes the compressed RAW setting as numerically lossy but visually lossless. Translated, that means the RAW data after compression is not numerically identical to the RAW data before compression: some picture information has changed. Like a low-compression, high-quality JPEG setting, however, Nikon is promising that it will not be possible to see the data loss. We hope this will be the case, as smaller RAW NEF files can only be of benefit in our workflow.

The D2H offers the following file format options:

  • JPEG Fine
  • JPEG Normal
  • JPEG Basic
  • TIFF (RGB)
  • NEF (compressed or uncompressed)
  • NEF + JPEG (Fine, Normal or Basic)

Unchanged from the current range of Nikon digital SLR models is the size of the large JPEG preview inside each photo. This JPEG preview, which is used by image browsers such as Photo Mechanic for Mac to provide a larger look at RAW NEF photos without processing the RAW data first, remains on the small side at 570 x 375 pixels. This means that the D2H NEF preview in Photo Mechanic, or any other browser that takes a similar approach, will look pixelated at a typical preview size.

In Capture 3.5, Nikon included a function that builds a JPEG preview into NEFs that is a useful 1600 pixels wide. We thought this function might be foreshadowing a similar preview size in the next generation of camera from Nikon, but that has not come to pass.

ISO

nikon_d2H_screen_iso.jpgThe D2H, like the D1H before it, offers an ISO range of 200-1600 in 1/3, 1/2 or 1 step increments plus ISO 3200 and 6400. Unlike the D1H, ISO 3200 (HI-1) and 6400 (HI-2) are now more conveniently listed in the standard range of ISO settings, as opposed to being tucked away in a Custom Setting that you have to dive into everytime you want to step above ISO 1600. Also new in the D2H is an Auto ISO setting.

As we pointed out in the sensor section, while Nikon is not offering an increased ISO range in the D2H, they are promising a more usable ISO range, perhaps right up to ISO 6400, because of the claimed low noise of the new sensor and noise reduction during image processing.

Auto White Balance

Nowhere is the depth of Nikon's engineering effort more apparent than in the design of the D2H's white balance controls. The Auto White Balance (AWB) function in particular has been rebuilt from the ground up to give neutral colour in the broadest range of shooting environments. At 2500-10,000K, its operating range is wider than any other digital camera we know of. And it makes its AWB calculation from three inputs:

  • The 1005 pixel metering sensor, which in the D2H (and D1-series cameras) also provides colour information to the AWB system.
  • The LBCAST image sensor (not the image data) itself.
  • A new Ambience Light Sensor mounted in the camera's prism. We're not sure why it's called the Ambience Light Sensor, as opposed to the Ambient Light Sensor, but there it is.

nikon_d2h_ambience.jpgIn addition, the Ambience Light Sensor (shown at left) is able to detect the flicker of artificial lights such as fluorescent, mercury vapour and the like. The flicker is really a strong shift in the colour being emitted by the light source during each on/off cycle (there are usually 50-60 such cycles each second).

As it has been explained to us, once flicker has been detected, the AWB system compensates by applying a different balance frame-by-frame as needed to counteract the per-cycle colour shift. Egads, if this works it could be of tremendous benefit to sports shooters in particular, since the colour shift really only becomes nasty at action-stopping shutter speeds (1/60 is typically the threshold; above that you'll increasingly experience the problem).

We know of several local venues, including one amateur hockey arena, that are enemies of good colour because of the flicker. Our fingers are crossed. We would like to see this capability built into the camera's Manual and Preset WB settings too.

In addition, the Speedlight SB-800 communicates information about flash duration, as well as detailed colour information, based on the intensity of the flash burst. The colour information is comprised of the spectral composition of the light at 11 different points across the visible spectrum. This degree of precision is staggering. In fact, we're having trouble wrapping our minds around the notion that the D2H's AWB system can absorb info from its own three inputs, plus the SB-800's contribution, and come up with a usable colour balance. Our hats are off to the engineers who cooked up this idea in the first place.

One hiccup of the AWB system in the D1X and D1H arises when colour correction gels are used with a flash such as the SB-80DX. These cameras, when set to Auto WB and used with a compatible Nikon Speedlight, essentially lock themselves on Flash WB, thereby ignoring the changed colour output of the strobe. This has rendered Auto WB all but unusable when shooting with a gelled Nikon strobe with the company's current pro digital SLR models. We hope that the D2H will handle this differently, especially in light of the fact that the SB-800 will ship with colour correction gels.

Manual White Balance

In its current line of cameras, Nikon already has one of the most usable ranges of Manual White Balance settings. It's good to see, then, that the Manual White Balance settings are unchanged in the D2H, though there are a couple of noteworthy additions.

New in the D2H is a Kelvin white balance control, incremented in 31 settings from 2500-10,000K. Each increment is meant to represent a 10 mired shift; put another way, each increment is meant to produce a visually similar change in colour. That's because the Kelvin scale is not linear: the visual difference between 2500K and 3000K is much larger than 9500K and 10,000K, for example. By comparison, there is a direct link between the numeric change and visual change in the mired scale: a 10 mired shift, whether the light is warm or the light is cool, results in the same apparent change visually.

Nikon has calculated the colour temperature values required to achieve a 10 mired shift throughout the working range of this feature. One oddity: by our own calculation, the shift is between about 6 and 16 mireds at the low end of the scale. Only when the numbers get large does the shift settle out at about 10 mireds. We suspect this is because of rounding to the nearest 50K in the Kelvin menu screen. The underlying increment-to-increment shift may well be 10 mireds throughout.

Also new is White Balance Bracketing. A total of 2 to 9 frames, in 10, 20 or 30 mired increments, may be selected.

Nikon's usual cast of characters rounds out the Manual White Balance options:

  • 3000K Incandescent (with +/-3 warm/cool override)
  • Fluorescent (7 settings that cover a range of fluorescent, mercury vapour and other artificial light sources)
  • 5200K Direct Sunlight (with +/-3 warm/cool override)
  • 5400K Flash (with +/-3 warm/cool override; tuned for Nikon Speedlights)
  • 6000K Cloudy (with +/-3 warm/cool override)
  • 8000K Shade (with +/-3 warm/cool override)

Preset White Balance

It would be quicker to describe the ways you can't set a Preset WB in the D2H. It's still possible to do it the old-fashioned way: by pointing the camera at a neutral object such as a gray card. But there are several other methods for getting white balance info into a D2H Preset WB:

  • Copying the white balance data from an existing photo
  • Taking a measurement with the Ambience Light Sensor
  • Performing an AWB-type analysis of an existing photo

nikon_d2H_screen_pwb.jpgThe D2H includes 5 Preset WB positions in all. Each one can be given up to a 36 character name, and the Preset WB menu screen includes a thumbnail of the photo from which the white balance was derived (we're not sure what's displayed when the measurement is from the Ambience Light Sensor only).

Nikon has sought to make the D2H's Preset WB a lot more versatile than any previous Nikon digital SLR. And while the feature's newfound flexibility is welcome, the primary and still most valuable method for setting a D2H Preset WB -  photographing a truly-neutral gray card - still requires that you fill the frame with the gray card (as with current and past Nikon cameras), instead of just a small portion of the frame (as with Canon and Kodak digital cameras).

Since filling the frame with the gray card is often a hassle, especially with wide angle lenses, we'd hoped that this legacy limitation would have been stomped out in the D2H.

Color Modes and Hue

The D1X and D1H were the first digital SLR's we know of to offer a choice of colour spaces and colour looks in the camera, all rolled into a Custom Setting called Color Mode. The D1X and D1H include 2 Color Mode settings; the D2H ups this to 3, the same number as the D100.

As with the D1X, D1H and D100, the colour look or colour intent for each D2H Color Mode setting is different. The D2H's Mode I and Mode II are built to give a similar colour look to Mode I and Mode II in the D1H. The D2H's Mode III is similar to the D100's Mode III. There are unspecified improvements in the colour processing behind each setting, but the overall appearance of each is promised to be very much the same as Nikon's current digital SLR models.

The same two colour spaces - sRGB and Adobe RGB - are also associated with the three Mode settings. All in all, this should mean that colour from the D2H is superb, as we've been unabashed fans of Nikon colour since the D1X and D1H were introduced in 2001. Here's Nikon's breakdown of the colour intent for the three Color Mode settings, and the colour space associated with each:

  • Mode I: Optimized for portraits and natural skin tones (sRGB)
  • Mode II: Optimized to realize a wider colour gamut (Adobe RGB)
  • Mode III: Optimized for landscape and flora colours (sRGB)

nikon_d2H_screen_colormode.jpgIn our experience, Mode II gives the most photographically naturally colour and is the best by far for portraits, Mode I is similar but noticeably more saturated while Mode III is a big departure from the other two: look for stronger saturation, heavier midtones and a noticeable hue and intensity shift in landscape colours (greens in particular). If this trio provides the same range of colour renderings as the D100, which also sports three Color Mode settings, the native colour of the D2H should be rock-solid.

We were hoping, however, for a change that would have brought greater flexibility to the selection of a Color Mode. In the D1X, D1H, D100 and now the D2H, when you choose a Color Mode setting you simultaneously select both a colour look and a colour space. That is, if you want to shoot rich landscape photos, Mode III is the best choice, but you're stuck with sRGB by doing so. It's not possible to link Adobe RGB with Mode III in the camera.

If you shoot RAW NEF, then you can do this after the fact. That's because Nikon Capture enables the choice of, for example, Mode III's colour look, but processed into the Adobe RGB colour space (or any other RGB colour space of your choosing). Since we've standardized on Adobe RGB for our editing space, we'd like to be able to standardize on Adobe RGB in the camera too, regardless of the file format we happen to be shooting.

Given that Nikon led the way in including colour look/colour space options in a digital SLR camera, we thought that by now they would be taking the next step and providing two separate controls, one for colour look and one for colour space. At least in prototype D2H bodies, this isn't possible. There are other changes we'd like to see, ones that relate to the use of a custom camera profile, though such features are probably beyond the needs of the photographer at whom the D2H is targeted. But at this point in the evolution of digital, separate switches for colour look and colour space are a must, and we hope it's still possible to roll that into the D2H before it ships.

As with current models, the D2H when set to Mode II will embed an Adobe RGB profile into each in-camera processed JPEG or TIFF photo. An sRGB profile is not embedded when the camera is set to Mode I or Mode III.

The Hue Adjustment of current cameras has been ported to the D2H unchanged. It has 7 increments, and it operates much like the Hue slider in Photoshop's Hue/Saturation tool when set to make a global adjustment.

Tone Compensation

nikon_d2H_screen_tonecomp.jpgTone compensation options will look familiar to current Nikon digital SLR owners. Technical information on the Normal, Less Contrast and More Contrast settings suggest that the tone curves applied will provide a result very similar to current cameras too. The dynamic range of processed photos is also expected to be similar, though cleaner shadows at a range of ISO settings may effectively boost dynamic range somewhat.

Also unchanged is the Custom option, which allows a tone curve defined by the photographer to be transferred to the camera from Nikon Capture.

The Auto Tone Control (ATC), however, has been signficantly revamped. It now draws from the same data well as the AWB system in determing the tone curve to apply. By analysing data from the 1005 pixel metering CCD, the LBCAST image sensor and Ambience Light Sensor, the ATC is designed to come up with the optimized tone curve on a per-picture basis.

Sharpening

The D2H provides the following sharpening settings:

  • Auto
  • Normal
  • Low
  • Medium low
  • Medium high
  • High
  • None
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