The State of Full-Frame Sensor Technology in 2014
When you’re looking for a new camera, the image sensor can end up just another bullet point in a list full of specs. It’s one of those things that’s ever-evolving in the digital landscape, promising us higher-quality images with the passing of every few years. In simplest terms, your image sensor converts light into an electronic signal. It’s the digital equivalent of film, and a critical part of any camera. Image sensors come in a variety of sizes and determine the specific qualities of your resolution, low-light performance, and dynamic range. For a true 35mm equivalent digital camera, you’ll want to limit your search to full frame. And you’re in luck: five incredible full-frame systems hit the shelves this year, with cutting-edge image sensor technology, to boot.
"For a true 35mm equivalent digital camera, you’ll want to limit your search to full frame."
The debate has raged for a while between CMOS (complementary metal-oxide semiconductor) or CCD (charge-coupled device) sensors, and which of the two is the way to go. At their core, both perform the same function: converting light into the electrons that make our image. CCDs are somewhat rarer these days, being the older, more mature, and more expensive piece of technology. Their construction and design is the more complicated of the two. In CCD sensors, each pixel captures light, and then transports the charge across the chip to an analog-to-digital converter. Originally, these mechanics ensured a nice low signal-to-noise ratio with optimal color rendition and dynamic range. When CMOS hit the market, a lot changed. For starters, its inexpensive and simplified production process lowered the cost of many high-end digital cameras. Then, camera function speed was notably improved. Since they sap far less power than CCDs, CMOS sensors enable things like higher continuous shooting rates and longer battery life. The CMOS design places transistors at each individual pixel, where light is captured, converted to a charge, and the signal is amplified. In the beginning, the main setback was lower image quality. Grain was excessive at high ISOs, along with lackluster color and detail reproduction. But, since technology has continued to evolve (including the advent of back side illuminated CMOS), these issues have become less of a relevant concern. Now, it’s safe to say the two chips are pretty evenly matched. As a matter of fact, each one of the full-frame cameras released this year includes a CMOS image sensor.
Last spring, the Sony Alpha a7S was introduced to much fanfare. Its two siblings, the a7 and a7R, had already earned accolades and notoriety for being the first full-frame mirrorless cameras on the shelves. With the introduction of the a7S came a 12.2MP Exmor CMOS image sensor that offered some major performance boosts over the other a7 systems, though they both still hold up as fantastic cameras for different applications. Its maximum sensitivity of ISO 409600 handles available or low-light shooting astoundingly well, and offers a remarkable four-stop advantage over both the a7 and a7R's top sensitivity of ISO 25600. Noise remains at a pleasantly workable level throughout the entire range, so there’s no reason to fear a high ISO. Since the sensor in the a7S contains much larger pixels than its siblings, it also captures excellent dynamic range. Scenes with extreme shadow and highlight aren’t as much of a struggle to photograph, which is a great relief on ultra-bright days or when shooting landscapes. And last, there’s the video. An anti-aliasing filter over the sensor prevents jagged edges in your shots, and you can shoot ultra high-definition video in 4K when hooked up to an optional external recorder. The a7S’s speed, low-light performance, and superior video capture make it an excellent event shooter’s camera. If you tackle a lot of weddings or concerts, and you think you’re ready to take the plunge into mirrorless, this is a great camera for the job.
Leica’s newest addition to the M series, the M-P, upholds the high standard that’s par for the course in these famously stylish rangefinder cameras. Though released this year, the M-P carries over the 24MP MAX CMOS image sensor from its predecessor, the M (Typ 240). When it was announced Leica would be ditching CCD for CMOS, many people worried about what it would mean for the company, so dedicated to outstanding image quality. Luckily, they weren’t disappointed. This little piece of technology still holds its own among a wealth of competitors, and is due our thanks for bringing several advantages to the Leica community we didn’t yet have. Custom designed by European imaging company CMOSIS, the chip is application-specific to the M and M-P’s needs. It's incredibly well crafted, and its high-quality build is meant to replicate the traditional characteristics of CCD sensors, including gorgeous color rendition and intricate detail reproduction. Unlike CCD sensors, however, the 24MP Leica MAX CMOS doesn’t sap an enormous amount of power. You end up with a quicker function-response time and much longer battery life than you’d have otherwise. Not only that, but it gave Leica enthusiasts the option to finally shoot video in full HD 1080p. Live view mode is also now available, so you can compose without the viewfinder by using the camera’s 3.0" LCD screen. It yields excellent low-noise images, thanks in part to both analog and digital double sampling, up through its maximum ISO 6400. This sensor’s wide pixel aperture also allowed for the first time ever, starting with the M, compatibility with both M- and classic R-mount lenses. The German company holds a steady fan base among street and fine art photographers, as well as enthusiasts who can’t get enough of the Leica brand.
This has also been a huge year for Nikon, who introduced three beautiful new full-frame (or FX) DSLRs to its lineup. First up was the D4S, announced in late winter and ready to ship by early spring. If the D4S looks familiar, that’s because it is. Essentially, it’s an updated version of the beloved D4, Nikon’s flagship high-end professional camera from previous years. The D4S boasts a few new system improvements, including a refined image sensor. On paper, both cameras list a 16.2MP FX CMOS chip. Where the D4S takes the lead is in its improved low-light handling and noise reduction, offering a native ISO of 100―25600, which is further expandable to ISO 50―409600 to provide a boost of one more stop than the D4. Apart from its noise-canceling improvements, the D4S has a slight edge on detail reproduction, color rendition, smoother tonal gradation, and better dynamic range. It’s also a bit faster than its predecessor, with a continuous shooting rate of 11 fps versus the D4’s 10 fps. The D4S is ideal for serious press photographers and folks who typically rely heavily on the speed and efficiency of a high frame rate, such as sports, wildlife, and other action shooters whose decisive moment can fly by in an instant. Other professionals (wedding, portrait, etc.) and passionate hobbyists should instead turn to one of Nikon’s other two new FX bodies, which sell for a fraction of the cost of the hefty D4S.
In June, Nikon announced full-frame system number two, the D810. The D810 followed a similar formula as its bigger D4S sibling. It took many of the already great features from its popular predecessors (in this case, the D800 and D800E) and simply improved upon them in ways that gave users a slight edge. Like its previous model, the D810 comes with a 36.3MP FX CMOS image sensor. On paper, this may seem like no change at all. But, don’t be fooled: Nikon has taken some pretty solid strides in redesigning the CMOS sensor for some noticeable boosts in performance. The first big change is the omission of an optical low-pass filter (OLPF), a tool used to correct for moiré, aliasing, and false color rendition. The OLPF works by blurring the image just slightly, which ends up being a double-edged sword. While you avoid moiré and aliasing, you also lose some valuable information in the details. Omitting the low-pass filter on such a high-resolution image sensor, such as the D810’s, allows high-frequency image information be recorded without interruption. This translates into a nice, noticeable increase in sharpness. Because the D810’s sensor has such fantastic resolution, the threat of moiré and aliasing becomes less of an issue, even without the filter. It’s a win-win situation for anyone who works with this camera. A few other major improvements include a boost in continuous shooting rate by 1 fps, support for a video frame rate of 60 fps, and a 30% increase in battery life, from 900 shots per charge to 1,200. There’s also a nice jump in sensitivity, with the D810’s native ISO 64―12800 offering a stop more light than the D800’s maximum native sensitivity of 6400. It’s also expandable from ISO 32―51200 and offers excellent handling over noise, making it a great professional low-light camera system. Another plus is its improved color-rendering capabilities and broadened dynamic range, so less information ends up lost in areas of extreme shadow or highlight. This camera is a fantastic buy for videographers or professional still photographers. Its excellent dynamic range and noise-canceling performance make it a top choice for wedding, event, or other type of available-light shooting. It won’t matter if the sun’s too bright, or there’s barely enough light at all; the D810’s sensor has it covered.
Last, but certainly not least, the industry darlings at Nikon presented us with the D750 earlier this fall. For a few hundred dollars more, the D750 surpasses its older, entry-level FX sibling, the D610, in a range of newly designed features including the image sensor. At face value, the specs seem the same. Both systems harbor a 24.3MP FX CMOS sensor, but the newer chip has been given an update to yield stronger-quality images. The D750’s dynamic range is rich and broad, with accurate color rendition, smooth gradation, and beautiful contrast. This remains true throughout any lighting conditions, whether too bright or too dim. Highlights retain information without being blown out, and noise levels remain workably low throughout the entire sensitivity range. Nikon has achieved this by increasing the pitch of each individual pixel on the sensor, making it easier to obtain valuable light information with each shot. The D750’s native ISO 100―12800 sees a nice jump in sensitivity, offering one stop more in sensitivity than the D610’s native ISO 100―6400. It’s also extendable to a boosted ISO 50―51200, making it easy to shoot in diverse available light. The continuous shooting rate sees a bit of a jump—around 10%, to be specific—from the D610’s 6 fps to the D750’s 6.5 fps. Filmmakers will see a bit more of a substantial advantage here, which is the D750’s ability to shoot video in full HD 1080p at 60 fps versus the D610’s 30 fps. Last but not least, the re-designed CMOS chip saps a fraction of the power needed to operate the older D610. The D750 can pull off 1,230 shots per charge, which is a wildly efficient 40% increase. While the D610 remains a fantastic FX body, for a few hundred dollars more, the D750 has proven that it makes up where the former falls short. The D750, much like the D610 before it, is geared toward semi-professionals and knowledgeable enthusiasts. It also makes a fantastic second or backup body for busy, serious professionals. If you’re after the high-quality resolution of a full-frame camera system without going overboard in cost, Nikon has you in mind here. Its capability, not to mention price, will land you on a comfortable stepping stone between the D610 and the D810.
So, what can we expect in the coming years? Any piece of digital technology becomes more refined as time passes, and the same will undoubtedly prove true for our image sensors. Down the line, we’ll continue to see improvements in low-light handling, noise cancellation, dynamic range, and sharpness. The images we’re producing right now are already incredible. It’s exciting to think about how much is yet to come.