The EOS-1D Mark IV camera has a new APS-H-size CMOS sensor (imaging area 27.9 x 18.6mm, approximately 1.3x lens crop), using semiconductor manufacturing equipment -- both designed and manufactured by Canon. This sensor enables professional-level performance in every respect. Its resolution is approximately 16.1 megapixels (4896 x 3264 pixels). Its normal ISO range is 100 to 12,800. The range can be extended via ISO Expansion down to L: 50 and up, via H1, H2 and H3 to 25,600, 51,200 and, incredibly, to 102,400.
Its low noise, high-speed signal reading produces 10 fps in continuous shooting, even with noise reduction on. In addition, the sensor handles Live View full HD video shooting. In all, it is a remarkable example of cutting-edge sensor technology.
Despite a smaller pixel size than that of the EOS-1D Mark III (5.7 versus 7.2 microns), design objectives—now achieved-- for the new sensor included: a superb S/N ratio, high-speed and low-noise image development, high ISO speeds and wide dynamic range.
Canon’s improved semiconductor fabrication technology has enabled a new method of photodiode construction. Photodiode area is optimized and photoelectric conversion efficiency is improved. This allows more light energy to be accumulated and transferred even though pixel size has been reduced.
To improve light-gathering efficiency further, another new and critical process has been incorporated in the fabrication of the microlens over the sensor so that there is no gap at all between the microlenses. Additionally, the distance from the microlenses to the photodiodes has been reduced compared to earlier designs, improving efficiency even further.
Several additional significant technical developments contribute to increased S/N performance. A new material used for the sensor unit’s RGB primary color filters improves transmittance. In addition, the circuit for applying high gain now suppresses noise from outside the sensor, improving resistance to noise and resulting in low noise even at high ISO speeds. Finally, a preamp whose internal gain has been doubled is incorporated, further increasing S/N.
The gapless microlenses, the higher photodiode area ratio (photodiode area divided by pixel size), the new color filter material, the reduced microlens-to-photodiode space, the improved external noise suppression and the high-output preamp all enable the admirably improved S/N ratio which is, in turn, directly responsible for the higher ISO speeds, low noise, and wide dynamic range that distinguish the EOS-1D Mark IV’s performance.
Compared to the EOS-1D Mark III, the result is an improvement of approximately 1 stop in sensitivity at the sensor level despite the reduction in pixel size, and this is without considering the additional 1 stop of improvement for in-camera JPEGs that’s made possible by the advanced image processing technology of the Dual DIGIC 4 image processors. Therefore, all EOS-1D Mark IV users can benefit from the camera’s image quality improvements, even those users who prefer RAW captures only.
As in the case of the EOS-1D Mark III, one-line, 8-channel readout is incorporated. The high-speed amp, faster reading sequence, and higher reading frequency enable approximately 10 fps continuous shooting.
The basic construction and performance of the infrared-blocking, low-pass filter on the front of the sensor unit are the same as that of the EOS-1D Mark III. However, the top surface of the infrared-absorption glass now has a fluorine coating to prevent dust adhesion.
Amazing High ISO Performance
At high ISO speeds, the EOS-1D Mark IV achieves exceptionally high image quality, including high resolution, minimal noise, and a sense of atmosphere and depth, all without compromising shooting performance (burst rate, continuous shooting speed, and so forth). These advantages enable new possibilities for image expression.
For example, it is now possible to capture high-resolution images at a 1/1,000 second shutter speed in almost any night game setting. The EOS-1D Mark IV is ideal for stopping the motion of athletes in dimly lit places such as stadiums, gyms and indoor swimming pools. The low light shooting capability of the EOS-1D Mark IV extends even further when shutter speeds slower than 1/1000 are used. This feature allows the new camera to create usable images in light so low that other cameras with less sensitive image sensors may miss the shot completely.
ISO 12800 is now within the normal ISO speed range, two stops higher than before. The normal ISO speed range is the widest among EOS DIGITAL cameras with ISO 100-12800 (in 1/3-stop increments). ISO speed expansion offers L: 50, H1: 25600, H2: 51200 and H3: 102400. Also, this is the first EOS-1D-series camera with ISO Auto. The default setting sets the ISO speed automatically within ISO 100-12800. When ISO Auto is set, even if the upper ISO speed limit has been set to H1, H2, H3 and the lower ISO speed limit to L with C.Fn I-3, the ISO range expansion does not take effect. However, if the upper/lower ISO speed limit have been set narrower than the normal ISO speed range, ISO Auto will set the ISO speed within the range set. With most previous EOS cameras having ISO Auto, the ISO speed was fixed at ISO 400 when the Manual shooting mode was combined with ISO Auto. However, with the EOS-1D Mark IV, the ISO speed is now adjusted automatically to obtain correct exposure for the shutter speed and aperture that have been set.
Of the approximately two stops higher sensitivity that the EOS-1D Mark IV has over the EOS-1D Mark III, one stop is due to the improved CMOS sensor and the other is attributable to the performance boost of “DIGIC 4” rather than “DIGIC III” image processors.
ISO Auto in Manual mode with the EOS-1D Mark IV
Automatic control over ISO speed has become a popular feature among digital SLR users. Clearly, it adds a new dimension to basic exposure control that was never available with film cameras, but perhaps more importantly it opens the door to a wider range of photographic expression.
When using ISO Auto in the EOS-1D Mark IV’s Manual exposure mode, the aperture and shutter speed are fixed and the ISO speed for the correct exposure is set automatically, and displayed in the viewfinder, on the top LCD data panel or on the LCD monitor during Live View when the shutter button is pressed halfway. When shooting in places such as a stadium with a mixture of bright light and shadows where there are large differences between the high and low values, this is a handy function. In situations where neither aperture value (depth of field) nor shutter speed (avoidance of subject blurring) can be sacrificed, ISO Auto + Manual exposure mode can be a welcome answer.
With all C.Fns at their default settings, ISO Auto for still photography with the 1D Mark IV is always automatically set within the range of ISO 100-12800. Even if the upper ISO speed limit is set to H1, H2 or H3 and/or the lower ISO speed limit to L with C.Fn I-3, the ISO Auto speed range for still photos will be ISO 100-12800. However, if the lower and higher ISO speed limits have been set to a narrower range via C.Fn I-3, ISO speed will be automatically set within that range. Also, if ISO Auto is used in Bulb mode or with flash, the ISO speed will be fixed at 400. However, the ISO Auto speed range during video capture in Manual exposure mode can extend from 100 all the way to 102,400 if H3 is selected as the upper limit in C.Fn I-3.
More Articles by this Author
by Chuck Westfall
by Chuck Westfall
by Chuck Westfall