Photo Performance & Function
Given the small, pocketable size of the RX100 IV, one would not expect the performance to be that astonishing. Fortunately, this is far from the truth as both the images and video results of this camera can be mistaken for a model double its size and price under suitable conditions.
Since this is one of the most notable upgrades in regards to hardware, I wanted to touch on how well it functions in the real world. While the overall size of the viewfinder unit remains a bit too small for my liking, the clarity is vastly improved thanks to the bump in resolution. The clarity of the image, as well as the various camera settings shown in the heads-up display, are crisp and easy to read.
One of the biggest complaints about the previous generation RX100 III was that closing the viewfinder automatically shut down the camera with no way to disable this feature. Fortunately, this time around Sony listened and added a simple setting in the menus to disable this option and keep it powered on even after the EVF is retracted back into the camera body. However, just like the RX100 III, engaging the EVF will always power the camera on when in a dormant state.
Sharpness Comparison (f/1.8 – f/11)
Considering this is a fixed-lens camera, the sharpness is ultimately determined by the Zeiss glass that is integrated into the camera body. Zeiss is well known for their quality optics and in the RX100 IV's case this is no exception. When pixel peeping, there is some noticeable softness at the edges when shot wide open, but the center remains rather consistently sharp throughout the range. Peak sharpness appears to be a f/5.6 as diffraction slowly takes its course when stopped down. Overall, I'm pleased with the sharpness of this integrated lens and the resulting image quality is stellar for such a small camera.
ISO Comparison (100 – 12,800)
While the sensor itself isn't much different from last year's version in terms of size or MP count, the sensor has been stacked and now is backside illuminated thus resulting in faster performance for both stills and video. Along with the increase in efficiency, we are also able to notice a significant improvement in low-light performance with cleaner images and less noise at higher ISO values.
As you can see from the comparison above, the RX100 IV images hold out well in terms of noise all the way up to its 12,800 ISO cap. The sample images displayed here are straight out of camera RAW files with no noise reduction applied so the built-in noise reduction filters in Lightroom CC or Capture One Pro 8 can often clean up the high ISO images without much effort.
From my analysis, the RX100 IV doesn't experience much in terms of noticeable noise until you get up to 1600 ISO though it still remains very usable. As you advance a full stop to 3200, the noise becomes more apparent (especially in the darker shades) yet still adequate for most straight out of the camera.
Jumping up to 6400 ISO, more noise creeps in and starts to become apparent within the lighter values and more distinguished within the darker areas. Maxing it out at 12,800, the noise is noticeably present throughout the image though the level of detail on the subject is still rather good considering the circumstances and leaves plenty of room for noise reduction.
DOF Comparison (f/1.8 – f/11)
The depth of field is another factor that is increasingly difficult to achieve with a pocket camera like this that due to its smaller sensor size. Fortunately, thanks to the glass that is integrated within the RX100IV, the depth of field is rather impressive at its f/1.8 aperture, but isn't able to achieve nearly as much bokeh as its bigger DSLR and mirrorless siblings.
Thanks for the beefed up internal specs, the RX100 IV's autofocus capabilities have seen a large shift in efficiency when taking photos. The increase in speed is great for moving subjects or making a quick transition to capture an unrepeatable moment. I have been very pleased with the snappy and accurate AF throughout the various AF configurations offered within the RX100 IV.
I love Sony's execution of their face detection and newly added Eye AF detection. When shooting portraits or family photos, the ability to have the camera accurately determine your subject remain in focus is of great convenience. The Eye AF function will need to be mapped to a custom key through the settings menu, but once completed it will lock onto the nearest eye of your subject as long as the button is held down which is something only a few cameras offer at this time.
There are several trouble areas due to the smaller sensor, and one of those is the overall dynamic range. While the sensor performs extremely well for its overall size, you will not get the resulting dynamic range that we have come to expect from a larger sensor like an M4/3, APS-C or full-frame.
When shooting in RAW, I was impressed by how much detail you can bring out of the highlights and shadows in post-processing software like Lightroom 6 or Capture One Pro 8 without the image falling apart. Since I won't be too critical, I am satisfied with the dynamic range offered from the RX100 IV's small sensor though it does fall short of a competitor like the Panasonic's LX100 that harnesses M4/3 sensor though has a larger form-factor.
Metering & Auto White Balance
Coming from a Canon background, I've never really been that confident in their camera's built-in metering or auto white balance features. Even when dealing with my $3K+ 5D Mark III, I often found myself in situations where the camera metered or determined the white balance incorrectly.
Every since I picked up my a7S, I have been impressed with the accuracy of both the integrated metering and white balance detection. It is rare that I find myself having to tinker much with the exposure or white balance within a post-processing software when dealing with RX100 IV images and that saves me a great deal of time in post. In the event that the RX100 IV incorrectly meters or white balances the scene, it can be easily corrected when my images are shot in RAW.
15fps Continous Burst Shooting
With the new BSI Exmor R CMOS Sensor, the RX100 IV gets a 5x increase in readout speed thus allowing things like higher frame rates for continuous burst shooting. It is pretty mindblowing to think this little camera is capable of capturing up to 16 frames per second continuous burst with full AF capabilities at its full 20.1MP. From my experience, this feature has worked well with a reasonable buffer suitable for capturing critical action shots.
The ability to flip the rear display up 180-degrees and see yourself in front of the camera lens makes this camera is perfect for those who love selfies. While I rarely ever take a selfie, I could see this feature being beneficial in travel situations where you'd like to snap a picture of yourself in front of a famous landmark (Mount Rushmore, the Eiffel Tower, the Grand Canyon, etc.) to capture the memory and document your trip.
The widest part of the RX100 IV's lens captures selfies with ease and when shooting wide open you'll get a result where you are sharp, but the background is out of focus thus drawing attention to you as the main subject in the frame.
Video Performance & Function
4K UHD Detail & Limitations
When the RX100 IV was first announced, many were blown away by the idea that you could shoot 4K UHD out of such a compact, “point and shoot” style camera. While Panasonic's LX100 did offer this capability first, it does not provide a tru t ly pocketable design like the RX100 thus ruling out many buyers.
In terms of detail, the RX100 IV shoots excellent video quality in both 1080P and 4K UHD although most won't notice a different in 4K footage unless you are viewing your footage at a native resolution (requires a UHD display). However, the benefit of shooting in 4K and delivering your content in 1080P is you get great advantages in post production as you get great flexibility when adjusting the framing of your shot and offering ample zoom potential without a loss in quality.
There are two bottlenecks for shooting 4K UHD out of the RX100 IVand these can be obnoxious to deal with. First off, you need a fast memory card that is capable of efficiently handling the cumbersome data rates that are associated with shooting such a high resolution. In my case, I use the Sony 128GB Class 10 U3 card as it offers sufficient speeds with ample storage although Transcend also makes a similar card hat works great at lower price-point.
While the first bottleneck can be easily avoided with the investment in a high-speed card, the second one involves overheating, and this one is not as avoidable. When Sony announced the 5-minute cap when shooting 4K with the RX100 IV, many assumed it was similar to the cap on some EU cameras which only present due to tax laws. This is not the case with the 5-minute cap as the RX100 IV's small form-factor has trouble handling the heat dissipation thus resulting in overheating issues when shooting 4K at long lengths.
Many variables will play into how soon it experiences the high-temperature warnings including how long you record for, the position of the rear LCD screen and the environment you are recording in. In a cool setting, you can get the full 5 minutes of 4K without much issue though you may face a high-temperature warning that will warn you that the camera is getting hot and will eventually shut down.
When it does shut down, you'll have to wait 5-10 minutes for the camera to cool down before it is back to normal operating conditions. While this is frustrating to work with, there is not much Sony engineers could do to get us the best of both works, internal 4K UHD as well as such a small, pocketable form-factor.
Just know the overheating issue on the RX100 IV is only present when shooting 4K UHD and only when shooting clips longer than 2-3 minutes at a time so shooting in 1080P or shorter 4K clips are still handled with ease.
Dynamic Range & Slog 2 Support
Much like the stills, the dynamic range of such a small sensor is limiting especially in a video sense as you do not have the extra RAW data to recover from. Despite this, the RX100 IV keeps up as best it can in the video sense and in most conditions a non-trained eye won't notice any obnoxious blown out highlights or crushed blacks as long as you expose correctly.
For someone who is trying to get the most out of their RX100 IV in terms of dynamic range, shooting in the newly added Slog 2 picture profile will maximum this. However, if you aren't familiar with Slog 2, do note that your image will look pretty awful straight out of the camera, and each clip will need to be modified in post in order to achieve a pleasant outcome.
Shooting in Slog 2 can be very tricky for someone who has no experience with it and frankly I wouldn't recommend it unless you know what you are getting into or have an external monitor to help meter your scene correctly. The reason for this is the washed out Slog 2 version you'll see on the RX100 IV's built-in display is not a reliable base to work from and as a general rule of thumb you want to be shooting 2 stops over without clipping the highlights. I choose to shoot Slog 2 using my SmallHD 502 monitor that harnesses support for a waveform monitor and 3D Luts, but if I don't have it with me I'll just shoot in another more forgiving picture profile.
Another difficulty that comes with the Slog 2 support is that you must shoot at the native ISO as a minimum, which in the RX100 IV's case is ISO 800. The trouble lies when you are shooting a brightly lit scene (such as outdoors) at 800 ISO and a low f-stop. In a case like this, the scene can become overexposed very quickly so you'll either need to stop down to f/11 or enable the internal ND filters that help, but under extremely bright conditions I've still struggled when shooting at f/11 and the most powerful built-in ND filter enabled.
High Frame Rate & Slow Motion
The new internal hardware has not only sped up the frames per second for continuous stills shooting, but also for video with a new mode called HFR or High Frame Rate. When switched to this setting, you can shoot short buffered clips with no audio or focus changes at 240fps, 480fps, and 960fps for NTSC, which vary by resolution and are automatically upscaled to 1080P.
While the potential of achieving nearly 1000fps on a compact camera like this sounds awesome on paper, it is more of a party trick than a usable feature as the implementation is rather limited, and the resulting quality is far from spectacular. The process is clunky and far from efficient as it is very easy to miss out on the action with the short buffer period let alone deal with the poor resolution with gets murky rather quickly when upscaled.
While I would not rely on any HFR stuff in a serious environment, the 120fps at 1080P continuous capture mode is stellar and something I wish my a7S or a7RII were capable of. The resulting footage is gorgeous offering 25% playback speed when placed on a 30fps timeline and no buffering necessary.
The RX100 IV harnesses a built-in microphone for audio support while capturing video. Unlike some competing models in this price-point, there is no external audio in meaning that you'll have to settle with the mediocre audio internally or if that isn't good enough, you can use the internal audio capture to sync the audio from any external recorder in post.
Low-Light Performance For Video
The RX100 IV's new BSI sensor shows notable improvements for low-light performance though the noise levels will be more noticeable in video than photos as video noise moves. For everyday home video or hobbyist shooting, you may not even know what noise is or care that it creeps into your footage when shooting in low-light. From a prosumer/professional stand-point, I would not push the ISO much more than 3200 (though some may be okay with 6400) or the footage ends up becoming too noisy for my taste.