Thursday, July 30, 2015

Sony RX100 Mark IV Review

Sony RX100 Mark IV

The Sony RX100M3 was one of the best received cameras for first time shoppers and young families looking for something to take quality photos with.

Wait, what?

The RX100 cameras have never been inexpensive, but since the very beginning they have been universally well regarded. Even if they are loaded with specs that appeal to hardcore enthusiasts, the product line has successfully crossed over from high-end enthusiast to mass-market consumer. This is is no small feat; there are many good cameras, but few at the higher end compel casual shooters.

Taking a step back, the camera industry has gone through a sea-change these past few years. It used to be that if you wanted quality you bought a DSLR, and if you wanted portability you bought a compact. Mirrorless and high end compacts have changed that and made for more choice in between. Whereas before casual shoppers spend somewhere between $500 to $700 USD for an entry-level DSLR, they are now more likely to spend the same amount on a mirrorless camera or a RX100M3. It's a rational choice; for almost the same quality as a DSLR from 3-4 years previous, you get a smaller and more compact system.

The RX100M4, however, will likely not follow in that tend. When it comes to high end products, Sony deliberately aims for the top of the market with their halo products. That was true for the previous iterations of this camera, but there are diminishing gains to contend with. the RX100M4 has cutting edge technology and performance. Conceivably, one day it too will be an older camera that is overshadowed by the next biggest thing, but even when that day comes, its  biggest competition will still be its predecessor.

Build and Design

Externally, there is nary a change between the Mark 4 and the Mark 3. If you've used the previous camera, the Mark 4 will feel comfortable. Except for a a few differences, the similarities extend to the menu system as well.

Ultimately, this is a sign of design maturity on the part of Sony. This isn't back-handed compliment; Sony's camera line is still you relative to Canon and Nikon, and with all young product lines there is tendency to tinker between generations. Even companies like Nikon are prone to this: e.g., Thom Hogan's "who moved my cheese" phenomenon with Nikon menus. However, Sony probably has the most standardized menu structure of all the camera companies at the moment.  Between the RX100 cameras, the E-mount cameras (A5000, A5100, A6000) and the A7 FE-mount cameras, the shooting menus and the deeper setup menus all look the same. This means that they all share the same positives and negatives. The layout is fairly logical at the top end, but the grouping of some functions could use tighter logic.

One external change that is not visible is the bump in resolution to the EVF, from 1.44M dots to 2.36M. The pop-up EVF has been one of the most popular features on the RX100M3; even the EVF is on the small side, it is clear and easy to use. The RX100M4 is visibly clearer than the RX100M3, but not as much as the spec sheet might indicate. Because we are talking about a physically small viewfinder, you don't necessarily see more detail... rather your eye perceives more of a global bump in micro-contrast.

One extremely disappointing omission is that given the upgrades to the video recording,  there is no dedicated microphone socket on this camera


Here is the difference between the RX100 III and the A6000 with kit lens in terms of equivalent aperture when compared to an APS-C sensor. What does "effective" aperture mean? It's easiest to think of it as either measure of the amount of background blur that the camera/lens combination can develop under equivalent conditions, or as a comparison of the safe hand-held shutter speeds.

Camera Diagonal Crop Factor Effective Max Wide Aperture Effective Max Long Aperture

Sony RX100M4 0.56 3.2 5.0
Panasonic GM5 0.77 4.6 7.3
Canon G1X Mark II 0.83 2.4 4.7
Sony A6000 1.00 3.5 5.6

The winner here is the Canon G1X Mark II by virtue of having the brightest lens paired with the second largest sensor. The RX100M4 is actually a tad bit brighter than the Sony A6000 equipped with the kit lens, but not by enough to make a meaningful difference. There is something that must be noted, however, and that is that depictions of equivalent apertures between difference cameras assumes that the sensor efficiency is the same between each camera, which is rarely true. Also being ignored is the subjective visual impact of the number of pixels and the differences in dynamic range.

In terms of visual impact, how useful is the RX100M4's "fast" lens? Shallow depth of field (DOF)is typically only feasible at longer apertures... think portrait shooting. Here is the total DOF (in front and behind point of focus) for the above cameras when photographing a subject at 10 feet with the camera at 70mm equivalent and maximum aperture, assuming 'typical' viewing size and distance. The GM5 is calculated at 60mm, the maximum for its kit lens. Just for kicks, the D7200 with the 17-55mm f/2.8 and the 85mm f/1.8 are thrown in. (85mm being slightly longer than the rest):

Camera Total DOF (in feet) at max aperture/longest focal length, at 10 feet

Sony RX100M4 1.23
Panasonic GM5 1.89
Canon G1X Mark II 0.97
Sony A6000 1.38

Nikon D7200, 17-55mm f/2.8 0.69
Nikon D7200, 85mm f/1.8 0.29

The take home message? If you want nice bokeh, a compact take-anywhere camera is not the tool, no matter how leading-edge it is. All of the cameras, save for the DSLR with the f/2.8 zoom or f/1.8 portrait lens will produce a wide zone of acceptable focus under portrait conditions. This is common sense for the Sony A6000, as even a little bit of experience will show that a kit f/3.5-5.6 DSLR/mirrorless lens only produces a modicum of subject isolation. However, what's remarkable about the RX100M4 is how similar it is to the kit DSLR lens under these conditions.

ISO 5000, f/2.5, 1/40s

In other words, you can do "bokeh" shots like with the lighting grid above, but the shallow depth of field effect only shows up when the focus point is close to the camera. Said in another way; the image quality of the RX100M4 is like a larger sensor mirrorless or DSLR, but the depth of field characteristics are more like a point-and-shoot compact.

Orient Mako, ISO 200, f/2.8, 1/40s

Minimum focus distance is 5cm; close enough for food photography but not quite enough magnification for stamp collectors... not without cropping.

The Stacked Sensor

The key technology feature of the RX100M4 is the stacked sensor. The 2nd and 3rd versions of the RX100 used backside illuminated sensors, which are essentially conventional CMOS chips flipped over. This moves the majority of the circuity, which sits in front of the light gathering substrate on a conventional chip, to the back of the chip where it is out of the way of the incoming light path. This means that the "well" effect caused by the circuit wires in a traditional CMOS sensor is ameliorated, allowing for more light to be gathered, as well as allowing for more light to be gathered at oblique angles to the sensor.

The stacked sensor in the RX100M4 takes things further by moving the the remaining read-out wires to below the chip in a separate layer. The first benefit of this is that there is a further (small) increase in light-gathering ability in the substrate, but the big benefit is that the read out circuitry can now be physically larger because it is in its own layer. This is how the RX100M4 can achieve its heroic feats of data acquisition (16 fps stills, 1/32,000s shutter speed, 960 fps (upscaled) 1080p video).

The downside is that the sensor costs more to produce. The expense isn't just in the fact that there are two separate layers to produce, but that they have to be mated with precision.

A side benefit of the increase data read-out capabilities of the new sensor is that it allows for faster and more reliable autofocus. The RX100M4 uses a purely contrast detect AF (CDAF) system, but there is some improvement over the RX100M3. Because the sensor can sample data faster, the lens system can make the quick micro-adjustments required for the CDAF system to work. Unfortunately, this improvement really only applies to AF tracking of fore/aft positioning, and primarily with single-shot focusing. In AF-C mode the camera is fairly quick to re-acquire focus if the subject moves out of position... "re-acquire" is the key phrase as the system never truly tracks a subject continuously like in a phase-detect system. Side-to-side position tracking via the AF Lock-ON setting is about as precise as it is with the other crop of contemporary Sony cameras... which is to say that it is usable but not terribly precise.

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.

All three of the following cameras (RX100M4, RX100M3 and Panasonic LX100) were shot with identical settings (24mm equivalent, f/4, centre-weighted metering, dynamic range optimization turned off, noise reduction turned off). Base ISO for the LX100 is ISO 200 compared to the ISO 80 rating for the Sony cameras.Click on images for 100% crop view.
ISO 80
ISO 200
ISO 1600

There's an obvious difference in image size between the RX100M4 and the LX100. Thad advantage goes to the Sony at low ISO, but the Panasonic makes better use of its pixels at higher ISO settings. There's a clear advantage in edge acuity at ISO 1600; the cross-over point is roughly ISO 800. The (dis)advantage is also due to  Sony's JPEG engine; even with noise reduction turned off, NR is never truly "off." Note that the RX100M3 exposes 1/3 EV brighter than either of the other cameras when set at the same settings under this test.

RX100M4 JPEG output is typical for Sony, high on contrast, sharpening and colour saturation with a bit of warmth. The following was shot in flat daylight fluorescent lights in dim indoor conditions. The camera does a great job of pulling vibrancy and detail out of the image, but the output isn't actually true to what the human eye would have perceived in that circumstance.

ISO 500, f/3.2, 1/30s

However, this is default tuning, and you can change the setting to your liking... as with any other camera. But for what its worth, the image tuning on Sony cameras belies the dual-nature of the company's camera business. Sony makes high-end enthusiast products, but they often include consumer-oriented design declensions mixed in.


Left to Right: Panasonic LX100, Sony RX100M3, Sony RX100m4

The obvious competition is with the similarly priced Panasonic LX100 and the lesser priced Sony RX100M3.  The RX100M3 has proven to be popular to enthusiasts and non-enthusiasts alike. The feature set appealed to experienced shooters and the small size was a hit with the consumer crowd. The LX100 is a different sort of camera that only appeals to the enthusiast crowd. It's still a small device, but market forces are relative, and compared to the RX100  cameras and the Canon G7 X, it is a large device.

The RX100M4 will likely fall into the same category as the LX100, appealing primarily to enthusiasts. For the casual shooter that wants something a bit higher-quality, the RX100M3 hits all of the check-boxes. The RX100M4 hits more, but the problem is that most casual shooters won't know what those check-boxes mean.

In other words, price is once again the issue. The RX100 series has pushed the price point up on what people are willing to pay for a compact camera. With the first generation, there was nothing like it, and it wore its high(er) price tag proudly. The difference in 2015 is that there are choices; you can get a more capable interchangeable lens mirrorless camera (Sony A6000, Panasonic GM-5, etc.) for less.

Concluding Thoughts

This isn't the upgrade to the well-received RX100M3; it's something new entirely. The majority of people buy cameras for stills and only use video occasionally. The feature package of the RX100M3 speaks for itself, and one of the lesser-known virtues of that camera is how good the video quality is. The RX100M4 is not merely an upgrade, it is something different. The stills-photography portion of the equation is not appreciably different for the majority of shooters, but the high-speed video frame-rate capability opens up unique opportunities for videographers.

In other words, the RX100M4's unstated purpose is to drive sales of the Mark III; the new camera is the technology halo product that brings people into the stores, but the Mark III is the one that they will buy. This was also true of the relationship between the RX100M3 and the RX100M2, but the better lens and built-in viewfinder were enough to make many consider the stretch up from the second generation to the third. We are likely at the point of diminishing returns with this generation now.

As a pure technology exercise, we are also at the point of diminishing returns in sensor technology. Every year noise goes down and resolution goes up, but these are evolutionary changes that are planned in advance at the marketing pipeline stage. The RX100M4 stacked sensor is something new, and more importantly, does something that is tangibly "new".

With thanks to Broadway Camera

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