Pixiq

Simon Stafford takes an in-depth look at shooting video with the Nikon D3s.

The D3s has inherited the essentially same D-Movie mode for recording video, as the Nikon D90 the world’s first D-SLR with such a capability that was launched during late 2008. However, The D3s, however, is the first Nikon FX-format D-SLR to offer a D-Movie mode, plus it incorporates a few further refinements, the most significant of which is full manual control over the shutter speed, lens aperture, and ISO sensitivity setting, a first among the Nikon D-SLR cameras with a D-Movie mode. All advanced enthusiast and professional videographers consider this level of control to be essential for producing high quality recordings. 

The basic video recording specifications for the D3s are as follows: 1280 x 720 pixel (720p) resolution, at 24-frames per second (fps) with Motion JPEG encoding, a maximum clip length at this resolution of five minutes (20 minutes at lower resolutions) and 16-bit/11.025kHz mono audio recording using the built-in microphone, and video files saved in the AVI format.

The D3s has the ability to use contrast detect AF in its [Tripod] mode recording and is fitted with a 3.5mm jack terminal for connecting an external stereo microphone for recording 16-bit/44.1kHz stereo audio, with both manual and automatic audio level control, plus there is a basic video clip editing function in the camera’s Retouch menu. Other options include the ability to use the full range of lens aperture values from the widest f-stop to the smallest, which can be set from the camera body when using Nikkor lenses with an electronic aperture control, there is the High-Sensitivity Movie mode that allows recording up to an ISO equivalent of 102,400, plus a “frame grab” capability that allows a selected video frame to be saved as a still picture in the JPEG file format. 

However, it is important to appreciate that there are a number of significant restrictions imposed by the system, because of the way that Nikon have implemented the video recording in the D3s. In essence what the camera designers and engineers have done is take the video feed from the camera’s sensor that provides the real-time image displayed by the camera’s Live View function and use this for its D-Movie mode. As such the choice of Live Mode ([Hand-held, or [Tripod]) makes a significant difference to the level of control you can exercise over the camera when recording video.

D-Movie Hand-held Mode

In [Hand-held] mode the camera adjusts the aperture value, shutter speed and ISO sensitivity automatically according to the scene brightness; Matrix metering is used regardless of the metering pattern selected on the camera. Hence in the [Hand held] mode the user relinquishes any control over a shutter speed, aperture, and ISO level. In effect the camera shifts into a fully automated point and shoot mode.  

This level of automation raises several issues:

• If the level of illumination in the scene being recorded changes, for example, the camera is panned from an area that is lit brightly to an area of deep shadow, or the focal length of the lens is adjusted, so the ratio of tones within the frame change significantly, the camera will just shutter speed and ISO accordingly in order to maintain what the camera considers to be an appropriate level of exposure. 
• As the ISO sensitivity level is increased there will be an inherent increase in electronic ‘noise’ in the image
• As with any automated exposure system, it is highly likely that if the scene is filled, or nearly filled with an extreme tone the exposure is likely to be inaccurate; with particularly dark tones it is like to be overexposed, while with very lights tones the scene will probably be underexposed. 
• Automated exposure adjustment by the camera is performed in a stepped manner causing a distinct and very noticeable shift in the level of illumination of the recorded image. 
• If the camera adjusts the shutter speed during recording the rendering of any moving subject will alter, becoming increasingly smeared at slow shutter speeds and taking on a staccato (jumpy) appearance at faster shutter speeds.

In [Hand held] mode the D3s does not perform any form of autofocus after recording has commenced, so place the selected AF point over the subject and press the shutter release down halfway, or press the AF-ON button to focus while still in Live View. Focus manually once recording has started; note that pressing the shutter release down halfway, or press the AF-ON button will cause recording to stop.

D-Movie Tripod Mode

To exercise some level of control over the D3s when recording in D-Movie mode, set the camera to its Live View [Tripod] mode. In A and M exposure modes the recording is made at the lens aperture value selected by the user; the aperture value can also be changed once recording has begun, providing real-time control over the depth of field. However, the shutter speed and ISO are still adjusted automatically by the camera; hence, the values for these two parameters displayed on the monitor screen in D-Movie mode (and Live View) may not represent what the camera is actually using!

While in [Tripod] mode for D-Movie recording, using any of the automated exposure modes (P, A, or S), the only way to apply exposure compensation, or lock the exposure level is to open the exposure preview mode by pressing the OK button after Live View has been activated (an analog exposure scale is shown on the right side of the monitor screen). 

• To apply exposure compensation, press the Exposure Compensation button and rotate the rear command dial; the level of adjustment is shown on the analogue exposure scale.
• To lock the exposure level, press and hold the AE-L / AF-L button (AE-L is displayed at the bottom of the monitor screen) enabling you to pan the camera across areas of different brightness, while maintaining the same exposure level; this assumes that the AE-L / AF-L button is set to one of the exposure lock options available under Custom Setting f6. To save having to hold the AE-L button down during recording I recommend selecting the [AE lock (Hold)] option under Custom Setting f6 [Assign AE-L/AF-L button]; now, once the exposure preview mode is active, press the AE-L/AF-L button once to lock the exposure and press it again to release the exposure lock. 

In [Tripod] mode the D3s can perform contrast-detect AF both while in Live View and during D-Movie recording by pressing the AF-ON button; however, since the contrast detect method of AF requires the camera to shift focus through the point of critical focus to measure the highest degree of contrast before re-focusing the lens to that point, and the system is relatively slow the use of contrast-detect AF during recording cannot be recommended. Manual focus can be used in [Tripod] mode and represents the most accurate and reliable focusing method.

Picture Controls & White Balance in D-Movie Mode

The Nikon Picture Controls of the D3s can be used for recording video in the camera’s D-Movie mode just as they can when shooting stills pictures. You can use any of the four default Nikon Picture Controls that are pre-installed on the D3s, including the Monochrome option for recording a black & white film, or either of the two additional Picture controls, Landscape and Portrait, which must be downloaded from a Nikon technical support web site, plus any custom Picture Control you have created and saved in the camera. Any of the parameters that can be set within a specific Picture Control, for example saturation, must be set before entering Live View, as the menu system cannot be accessed once Live View is active. Regardless of which Picture Control is selected it is important to avoid setting the level of contrast and sharpening too high, as the former will cause a reduction in the dynamic range the camera can record, while the latter can result is a ‘ghost’ image in which a black edge appears to follow any moving elements in the image.

White balance can be adjusted before and after entering LV, as well as during recording in D-Movie mode. Generally, you will want to establish the white balance in Live View and not alter it during recording. Live View provides the opportunity to make a real-time assessment of color rendition by checking the image displayed on the camera’s monitor screen; if necessary select a few alternative white balance options to see how these affect the colors but remember the screen is not calibrated to a fine degree and can only display a gamut of colors that approximates to the sRGB color space, so do not rely on the screen display for critical evaluation of color.

Taking control of the D3s in D-Movie mode

Most advanced and professional video / cinematic photographers make habitual use of full manual control over the shutter speed, lens aperture, and ISO. The D3s does provide this ability during video recording, although curiously this feature is not documented specifically in the Nikon D3s User’s manual and was only officially acknowledged by the Nikon Corporation some months after the camera’s release.

The D3s must be set to its manual exposure mode, and [Tripod] mode must be selected under the [Live View mode] via the Shooting menu. Next, press the LV button to active Live View, and then press the OK button to open the exposure preview option, so the analog exposure scale is displayed down the right side of the monitor screen. If you want to display a real-time composite (luminance) histogram, press the info button repeatedly to scroll the Live View information displays.

Configured in this way it is now possible to adjust shutter speed, lens aperture, and ISO manually, even during recording if required. There are still limitations on the range of values that the camera will actually use (see the chart below); note that while settings outside of these ranges can still be selected there is no guarantee they will be used, as the camera can and probably will override them. 

 D3s D-Movie limitations

There are several limitations built into the D-Movie mode of the D3s:

• The maximum file size for any single video recording is 2GB; this is due to the size limit on FAT 32 files
• The maximum duration for a single video recording made at the 720p HD (1280 x 720 pixels) resolution is 5-minutes. 
• The maximum duration for the use of the Live View mode / video recording is one hour, to prevent the camera from overheating and its circuitry being damaged. Provided the ambient temperature is cool it may be possible to reactivate Live View immediately; however, even in only moderately warm ambient temperatures it is likely the camera will shut down, automatically, long before the 60-minute limit. It is also worth remembering that since protracted use of Live View / video recording raises the internal camera temperature there will be a perceptible increase in the level of electronic noise in the recorded image.
• The audio recording capabilities of the built-in 16-bit mono channel microphone of the D3s, which has a relatively low sampling rate of just 11 kHz (most dedicated video cameras provide stereo channel sound recording with a sampling rate of 48 kHz) are somewhat limited, and are compounded by the fact that it will pick up even the slightest noise generated by camera operation, such as rotating a command dial, or adjusting the focal length / focus settings of a lens. Therefore, use of an external stereo microphone, or separate audio recording device is recommended. 
• When writing data continuously to the memory card at HD (1280 x 720 pixels) resolution video the D3s has a memory consumption rate of around 100MB/minute, which along with powering the monitor screen in Live View / video recording has a significant impact on battery power consumption, so it is highly advisable to carry several spare batteries if you anticipate a protracted video shooting session. 

Rolling Shutter Effect

The CMOS sensor of the D3s does not capture each frame of video simultaneously but records it in a scanning process of horizontal lines that starts from the top edge of the sensor and works toward the bottom. Consequently if the camera, or the subject moves rapidly during recording, the image of the subject will be recorded at different locations across the sensor, which causes vertical lines in static subjects that appear to be skewed in a diagonal direction, while moving subjects appear to lean in a rather exaggerated, cartoon-like manner.

A more pernicious version of this skewing effect occurs with a camera, which due to a lack of stability, moves laterally left and right during recording with the result that any static vertical lines in the frame area, such as the edge of a building, look as though they are wobbling, which is often referred to as the “jello” effect, due to the similarity to Jell-O, the gelatin based dessert food, when shaken.

While firmware improvements have mitigated against the worst of these unwanted effects with the D3s they can and do still occur; therefore, it is a matter of shooting appropriately, for example, panning the camera slowly, or following a moving subject accurately and accepting the inevitable distortion in the foreground and background. The single most effective step you can take is to use a dedicated fluid, or friction type tripod head designed for video work, to support the D3s when recording in its D-Movie mode.

In the final part of this article I will explain how to achieve a “cinematic look” when recording video with the D3s, as well as discuss some general shooting techniques, audio recording and preparing D3s D-Movie files for post-production.