Opinion: Did Sony just do the impossible?
1 Intro, Resolution, Dynamic Range
June 10, 2015 was a fun day. It saw the announcement of the Sony a7R II, along with the new 1"-type stacked sensors in the company's updated releases of the popular RX100 and RX10 camera lines. Our Editor Barnaby Britton was lucky enough to be at the launch event to witness the announcements in person, and with every text message he sent me about a new feature Sony was introducing in the a7R II, I couldn't help but feel like a kid in a candy shop being given far more candy than I'd expected. But like a greedy child, I was quite happy to take whatever was given me.
As a photographer intent on always optimizing his systems, I'm constantly on the search for the best tools for the job. As someone who also doesn't like to own too many things, spend needlessly, or have to choose which camera to take on which job (I hate making decisions), I'm also always searching for that 'one size fits all' option. Of course, as technologies evolve, our expectations increase, and so searching for 'perfect' is a bit of a fool's errand, as 'perfect' is a moving target.
So what we typically 'settle' for is 'as close to perfect' as we can get for our needs. But for the first time in a long while, I feel like we're getting much closer to this moving target. And for the type of photography I like to do* - landscapes, weddings, engagements, portraiture (especially candid and environmental), newborn, to name a few - here's why I'm almost unreasonably excited about the new Sony Alpha a7R II.
Getting the most out of all those megapixels...
42.4MP... ignoring medium format, who would've thought that we'd have to call that not class-leading? You can thank the Canon 5DS and 5DS R for that, which the a7R II falls short of with respect to resolution. And yet, in almost every other respect, the sensor in the a7R II is bound to outclass the 50.6MP sensors in Canon's latest high-resolution beasts. Why? Read on...
No AA filter
For one, there's no anti-aliasing filter at all, rather than the two birefringent filters in the 'anti-aliasing canceling' setup we saw in the D800E and, now, the 5DS R. Although the improvement may only be subtle, we saw slight improvements in micro-contrast when shooting our studio scene with a D810 vs. a D800E with the same exact lens (samples to be published shortly).
A bigger deal is that this is the world's largest backside-illuminated (BSI) sensor ever put in to a consumer-grade camera. BSI sensors flip the position of the photodiodes and the wiring of the sensor to allow more light to hit the photodiode without being obstructed by some of the other wiring and electronic components of the sensor. It's commonly understood that BSI has greater benefit for smaller sensors, as the smaller pixels have a larger percentage of their overall light-sensitive area taken up by electronic features, which don't necessarily get smaller as pixels get smaller.
However, this understanding is predicated upon a correlation of BSI benefit and pixel size, with the effect on sensor size only being an indirect correlation (since smaller sensors tend to have smaller pixels). But as we go to higher and higher resolution sensors, we may still have small pixels in a relatively large sensor. And such large, high resolution sensors may very well still benefit from BSI design. And that's exactly what Sony's thinking was - to not trade off resolution and sensitivity. We recently saw BSI help the APS-C Samsung NX1 achieve rather impressive low-light performance, and we expect to be similarly impressed when we test the a7R II, especially considering that the original a7R was no low-light slouch.
Shutter shock, or lack thereof
An issue we're becoming acutely more and more aware of as sensor resolutions increase is sources of mirror and shutter-induced shake. It was an issue with the first 36MP full-frame camera, the Nikon D800/E, and particularly so with the Sony a7R. All of these cameras initiate the exposure with a mechanical shutter, with DSLRs like the D800/E and 5DS/R having the additional issue of flipping a mirror out of the way first. When it comes to the mirror, camera manufacturers will typically dial in a bit of delay to allow for vibrations to die out, but even if this delay is 100% effective (our tests would suggest it isn't), a mechanical shutter often still causes some vibration, the effect of which will depend upon your focal length, as well as the duration of the exposure.
Very long or very short exposures typically won't affected, but we've found a whole chunk of shutter speeds, for example from 1/15s all the way to 1/500s, affected deleteriously by shutter shock, and optical image stabilization systems' reactions to such shock, at longer focal lengths on a Sony a7R, Nikon D810, and Canon 5DS.
Nikon's electronic front curtain on the D810, and Canon's use of an electronic first curtain in Live View, aim to mitigate these problems, but are cumbersome. Canon requires you to shoot in live view mode, and in the D810 you have to engage two shutter button presses with a delay in order to take a shot.
What likely made matters particularly worse for the Sony a7R was that the mechanical shutter had to be closed and opened to initiate an exposure, since the sensor is always exposed to light in a mirrorless camera. That's a lot of movement, with the shutter landing with a resounding thud! (literally sounding like it hits the bottom of the body frame) before opening again to initiate the exposure. At least with DSLRs, once the mirror is out of the way, the shutter only has to open (its 'default' position is closed). This shutter actuation was enough to cause significant motion blur in long telephoto shots, and even enough to cause a parasitic interaction with lenses' optical image stabilization systems to yield results such as the one below in our studio scene:
|Shutter shock plagued the original Sony a7R, and in the example above, which was taken at 1/100s with a Canon 70-200 F2.8L II IS attached via a Metabones Smart Adapter III, is not only obvious, but also reduces the resolution of the camera well below its lower-resolution peers, since cameras like the 24MP a7 at least offer a way to avoid this issue altogether (electronic first curtain).|
Thankfully, with the a7R II, Sony has doubled down on removing all sources of softness-inducing shocks. The shutter itself has been redesigned to minimize its impact, but the biggest story here is an electronic first curtain. The sensor readout speed has been increased sufficiently such that all the 42 million plus pixels can be reset fast enough electronically to not require the mechanical shutter to initiate the exposure at all. Like the a7, a7S, a6000, etc., when you press the shutter button, the entire sensor is reset electronically, and after the chosen shutter duration time, the mechanical shutter drops to end the exposure.
Furthermore, like the a7S, a totally silent shutter mode is available as well, with the exposure concluded, in addition to initiated, electronically. This likely comes at a cost though: we've seen additional noise in shadows with this mode on the a7S (it lowers dynamic range), as well as increased rolling shutter effect, to be expected as we haven't reached the holy grail of global electronic shutters yet with these sensors.
42.4MP is a lot. Enough for those large landscape prints I like to make every now and then, and enough to afford me enough cropping freedom to find photos within photos, or to strengthen compositions. But getting the most out of these pixels is increasingly difficult. Full-frame mirrors and shutters are rather massive, potentially creating lots of vibration that can blur images - at no fault of the photographer him/her-self. It almost behooves mirrorless cameras to have electronic first curtains, as there's no mirror to flip out of the way, making it that much easier to initiate exposures without any physical motion inside of the camera. The a7R II finally realizes this, offering an option to begin the exposure electronically, while ending the exposure mechanically (which typically doesn't affect the exposure deleteriously, since any induced vibrations occur at the end of, or after, the actual exposure).
This literally makes the a7R II the first high resolution full-frame camera with no potential source of mirror/shutter-induced shake during normal operation.
|The Sony a7 cameras are currently the only way to get quality Canon glass (and quality sunstars, with the 9-blade apertures in Canon's latest zooms) with expansive Raw dynamic range capabilities.|
The Sony a7R II will almost undoubtedly offer the Raw dynamic range we've come to expect and love of Sony sensors. And for a high resolution camera undoubtedly to be picked up by landscape photographers, dynamic range is bound to matter. With the latest generation of high performance, full-frame image sensors, we're starting to approach the point where many high contrast scenes can be recorded in one exposure, as long as you expose for the highlights and tonemap in post-processing. And for scenes still demanding techniques to work around dynamic range limitations, such as the very high dynamic range scene above, the higher the dynamic range of your sensor, the better.
For example, for this particular shot, taken with a Sony a7R and a Canon 16-35mm F4L IS lens, I've gotten away with just the use of a 3-stop GND filter, obviating the need to merge bracketed exposures - something I was in the habit of doing with my Canon EOS 5D Mark II. This allowed me to focus on other aspects of the shot, such as shooting f/22 for the sunstar, and f/8 for everything else (to avoid diffraction-induced softening for most of the shot), as well as focus bracket. Had I had to worry about exposure bracketing as well on top of all this, I might've missed nailing the perfect moment.
And even if it's not landscape photography you do, dynamic range helps - it offers you exposure latitude (the ability to 'rescue' exposures) and the ability to underexpose your images to retain highlight information by selectively brightening tones in post-processing, as I've done in this action shot of a horse galloping on the beach against a bright, setting-sun sky (above).
In fact, if I may engage in some speculation here: with the expanded photo-sensitive area of each pixel, and the off-loading of electronics to a separate area, one might wonder if the BSI sensor in the a7R II might offer even more dynamic range than its predecessor, as there may be room or capability for larger photodiodes and potential wells. I must stress that I'm purely speculating here, but we'll be excited to test if dynamic range has increased over the already high capability of the original a7R, and particularly if it catches up with the class-leading dynamic range of the Nikon D810 at ISO 64, where Nikon appears to have increased the full-well capacity of the pixels on the already excellent 36MP sensor from Sony (the more light you collect, typically the higher the dynamic range, unless read noise is the limiting factor).
There are many other interesting features the a7R II offers; read about some of them on page 2.
*You can check out some of my work at my not-so-up-to-date website, rishi.photography.
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