|Left: Nikon D7200 with Sigma 17-50mm f/2.8 OS Right: Sony A7mII with FE 24-70mm f/4|
Following the previous post that looked at the Nikon D750 versus the Sony A7 Mark II, two initial conditions can be roughly established:
- The Nikon D7200 is roughly one stop less in image quality (noise, dynamic range) relative to the D750 by virtue of its smaller sensor. Both cameras show JPEG rendering improvements over their predecessors due to the current generation of Nikon EXPEED processors.
- The Sony A7 Mark II, even though it is using a similar (but not identical) sensor is not as good as the Nikon D750 with out of camera JPEG's, and is limited by its compressed 11-bit RAW format
One wonders: how does the crop-frame D7200 compare to the full-frame Sony A7 Mark II? That might seem like a absurd question; of course full frame is better than APS-C. What's really the crux of the issue is whether or not Nikon's execution of APS-C can keep pace with Sony's implementation of full frame. The results might surprise you....
JPEG Image Quality
The following is an ad hoc demonstration of the camera's JPEG output quality through the ISO range. Pay attention to the legibility of the soda bottles for detail retention (or lack thereof) as the ISO value rises, speckling in the broad colour patches for overall image noise, as well as the harshness of the reflections and shadows as dynamic range decreases. These samples are not directly comparable to similar samples found elsewhere in this blog because of variable ambient lighting conditions.
Naturally, there is more processing leeway in the original RAW files, but comparing RAW files from different cameras can give one a false sense of fairness. Because each RAW format is different, the best and most representative results depend on each file being processed for best results. Often, different RAW files are compared at default converter settings, which is a bit like comparing default JPEG settings. Hence, for quick comparative purposes we are using the JPEG files out of the camera, as they can give insight into how the competing imaging engineers view the output of their respective cameras.
As demonstrated in the previous post, when comparing similar-sized sensors between the two companies, most people will find that the Nikon rendition holds on to more detail at high ISO. There is also an advantage in RAW processing leeway with Nikon's RAW format compared to Sony. The following is not a test of which sensor produces better ultimate output (the full frame one, obviously), but rather, how close image processing can being the APS-C sensor to the larger one.
Images were shot at 28mm with high ISO noise reduction turned off (or more correctly speaking, down) dynamic range optimization off and with centre-weighted metering. Note that the Nikon would prefer to expose the image 1/3EV more than the Sony under these circumstances, which would have brought the exposure on this small patch of the overall image closer to what the human eye would have perceived. Click on images for 100% crop view.
You can see that innately, the larger full-frame sensor has more potential image quality than the APS-C sensor at the same ISO level. However, past ISO 6400, Sony's aggressive noise reduction blunts detail to a larger degree than the D7200. This raises an important point: the reason why noise is objectionable is not just because it is unaesthetic, but because it reduces the amount of perceived detail in an image. The D7200 can credibly keep pace with the Sony because it is preserving more detail... in other words, even if the data noise is higher, so is the signal. Converted from RAW, the Sony will look better, with the exception that the 11-bit compression scheme that Sony uses reduces the amount of processing leeway compared to the Nikon format.
There are two conclusions that you can draw from this. Both are true:
- The Nikon D7200 is a very good APS-C camera when it comes to outright image quality
- The Sony A7 Mark II (and other Sony cameras) isn't reaching its potential due to how its images are rendered, both in JPEG and RAW
That last point is the key; Sony makes high-end hardware, but tends to include consumer-level features in the mix. While it is true that full frame users will want to use RAW, there are many times when JPEG will do just as well. JPEG may even be necessary when time is a factor. The fact that image noise reduction is never truly turned off when when it is selected as so in the menu is a concession to the consumer-oriented mentality that Sony has trouble letting go of. Less experienced shooters tend to prefer smooth looking images over noisier images that may also have more detail, and that's what they are getting.
In all fairness, Nikon is equally dogmatic as they have willfully kept default sharpening levels low (for enthusiasts) on their cameras for years, which gives some new owners the mistaken impression that Nikon image quality isn't as good as other brands. For their part, the current generation of EXPEED 4 processors perform admirably well. There a small improvement in hardware-level image quality over the EXPEED 3 generation, but the JPEG processing is ostensibly better.
This also shows a point about the camera market as a whole. There was a reason why cameras like the D7200 and the D300 before it were popular with enthusiast shooters; the serious APS-C segment offers most of the image quality of the more expensive full frame portion of the market, but with almost all of the handling features and serious-shooter design choices. In fact, that is why a system like the Fujifilm X-T1 gets so much attention; many X-T1 customers will probably have considered A Sony A7 camera before settling on the more economically rational choice. No matter how much the industry tries to lure photographers upwards towards expensive full frame systems, the fact remains that properly built APS-C system makes the most sense for the majority of shooters.
With thanks to Broadway Camera