Sony Alpha A7R IV Review
Performance - How well does it take pictures?
Image quality is a measure of the accuracy that a digital camera captures when facing a variety of scenes. It is the core criteria by which digital cameras are rated. This metric is a combination of sharpness, dynamic-range, exposure, color-depth, projection and uniformity, plus color, white-balance and tone-curve when rendering images. For an ILC, final image quality depends on both body and lens. Certain properties are determined by each component while sharpness is limited by the one that resolves the least amount of detail.
Given the extreme resolution of the 61 Megapixels Full-Frame BSI-CMOS sensor in the Sony Alpha A7R IV, the lens mounted is crucial to actually capture that much detail. There currently almost 90 lenses for Sony E-mount with Full-Frame coverage, many of highly-acclaimed image-quality yet only a handful have been tested such a high-resolution sensor, so certain lenses that perform extremely well on a 24 or 42 MP sensor may even look soft at 61 MP. Sony brands premium mirrorless lenses as GM with the remaining professional-grade lenses labeled G after the maximum aperture.
Image Noise & Details
The Sony Alpha A7R IV produces incredibly detailed images. Its 61 megapixels sensor maximizes resolution by being only covered by a standard Bayer Color Filter Array instead of having a second layer with an Anti-Alias Filter to avoid moire artifacts by slightly blurring incoming light. Increasingly, this is becoming the norm given that sensor resolution is so high that moire occurs much less. With a sufficiently sharp lens and its optimal aperture, this mirrorless captures the most minuscule detail of any Full-Frame camera yet.
From the minimum expanded sensitivity of ISO 50 to 400, images are completely free of noise. This allows for sharp images to be printing larger than poster-sizes up to 40 x 26". This is the top technical achievement of the Sony A7R IV. For scenes that can be captured within ISO 50-400, either with enough of light or with the camera mounted on a tripod, the output exceeds the resolution of most Medium Format cameras.
Very fine luminance noise appears at ISO 800 and 1600. This happens earlier than other state-of-the-art mirrorless cameras because these pixels are quite small. In fact, the A7R IV has the same pixel-size as a 24 MP APS-C with 1.5X crop-factor. At this point, it has a minor effect on maximum print size which are still possible until almost 36 x 24" poster-size. At more typical large sizes, such as 30 x 20", prints look impeccable. There is minor increase in luminance noise to reach ISO 3200. It only affects the finest details and the noise-floor remains sufficiently low to retain deep blacks and overall image contrast. At this sensitivity, the Sony A7R IV can still produce large prints after good noise-reduction is applied.
There is a significant jump in image noise at ISO 6400. Most of it remains luminance noise but we start seeing color noise intrude. At this point, there is a notable reduction in dynamic-range and global contrast. Noise reduction is capable of recovering contrast by smoothing out noise which transforms noisy details into softened ones. Still, moderately large 24 x 16" prints remain looking rather sharp after a fair amount of noise-reduction. This is where the A7R IV loses the advantage over its lower-resolution siblings, including its predecessor the A7R III
Sony Alpha A7R III and the A7 III
Sony Alpha A7 III that produce much smoother images at high ISO.
ISO 12800 follows the natural progression of this sensor. Noise increased further which damages even more detail and reduces contrast. Although chroma noise is more present, the A7R IV manages to keep colors balanced. More sophisticated noise reduction is needed to get good looking medium-size prints at this ISO. Neither detail nor dynamic range are recoverable at this point though. This sensitivity is very high and seldom used outside of action photography which is not ideal with this mirrorless.
The last full-stop standard sensitivity of the Sony A7R IV is ISO 25600, although there remains an additional ISO 32000 level which is nearly the same. Noise becomes stronger with a significant component of chrome noise that gives images a minor yellow tinge. The RAW output of the sensor still contains a fair amount of detail yet blacks turn into yellowish grey, making images look dull and aged. With noise-reduction is applied, images can look more natural. Small to mid-size prints are possible but the latter will look soft or noisy.
ISO can be expanded two stops beyond, reaching ISO 51200 and 102400. This are very high-gain sensitivities where everything gets applied, crushing detail and dynamic-range with large-grain noise. Most of it is still luminance which allows noise-reduction to relatively improve things. These two levels can produces images with a recognizable subjects and may be used for the smallest print sizes or publishing online.
The Sony Alpha A7R IV offers three levels of Noise-Reduction: Off, Low and Normal. Off is leaves pixels quite noisy which becomes really apparent starting at ISO 1600. This keeps details sharp yet lose contrast quickly. The Low setting fares much better throughout the entire range of sensitivities. It manages to minimize noise and restore overall contrast and color. Normal applies much more aggressive noise-reduction. At low sensitivities, this makes little difference. Starting at ISO 3200 though, details take a hit.. Unless frequently using high Expanded ISO, Low noise-reduction setting is preferable to Normal.
There two completely disjoint ways of specifying image parameters. One is called Create Style and works similarly to image parameters available on all digital cameras. Within a chosen Create Style, adjustments can be made to Contrast, Saturation and Sharpness. Rendition of details is directly affected by Sharpness. There are 11 possible levels on an arbitrary ±5 scale. Positive steps are quite fine, while negatives one are larger. The default of zero produces noticeably soft images that hide detail captured by the Anti-Alias Filter-Free 61 MP Full-Frame BSI-CMOS sensor in the A7R IV. Boosting to +2 makes details much clearer with optimum crispness at +3. Going beyond that introduces over-sharpening artifacts.
Picture Profile is the new way of controlling image rendition. Selecting any Profile other than Off makes the camera ignore all Creative Style settings. Although it offers a truly unprecedented level of control, it is excessively complicated and virtually impossible to configure for a desired output. There are over one sextillion combinations! This is roughly one thousand billions of billions. To be fully taken advantage of, one would need software that automatically optimizes all these parameters simultaneously based on a calibration target.
Color & White Balance
Color rendition is highly customizable on this camera. There are 11 Styles that can be chosen among Create Style options plus fine control over every color-channel and its complement among Picture Profiles. Both the Natural and Standard settings show reasonably good color accuracy. There is a small amount of oversaturation which is skewed towards the red channel in Standard mode but tuning down Saturation to -1 improves colors while retaining good vibrance. While technically more accurate in terms of Hue, the Natural mode is rather dull with very flat tonalities.
Much better color-accuracy can be achieved using Picture Profiles by tuning individual channels. This approach is more challenging though because all other parameters must be configured for optimum output as well. It is very difficult to render details with comparable sharpness as Creative Styles yet colors are easier to correct than detail.
The White-Balance system in the A7R IV is very sophisticated and capable of producing neutral colors under a wide variety of conditions. Between all 4 Automatic White-Balance options, there is generally one that produces pleasing results. Auto White handles indoor lighting better than average with only a slight yellow cast when confronted with low artificial lighting. The huge number of Preset WB settings can be used to quickly correct for obvious issues, while Custom WB is spot on.
Multi-Segment metering performed by the Sony Alpha A7R IV is balanced for mid-level exposures. Most scenes are captured with a conservative exposure that minimizes large areas of overexposure. It appears that segments are averaged before weighted to compute the weighed exposure. This causes small highlights to blow more often than expected without even reporting them on the histogram. Luckily, the EVF is exceptionally accurate which allows the photographer to often spot this issue before hand. Backlit scenes are often over-exposed due to exaggerated emphasis on the center of the frame.
Given that this mirrorless has a dynamic-range exceeding of 14-stops, the majority of scenes come out well-exposed. This wide dynamic-range is maintained at low sensitivities and then starts falling by 2/3 EVs for each additional full-stop ISO. Towards the upper-range of sensitivities then, metering is more susceptible to over-exposure. This shows that Sony is pushing the present limit of sensor design at its maximum.
Combining Phase-Detection at 567-point and Contrast-Detection in 425-areas allows the Sony Alpha A7R IV to autofocus quickly and accurately nearly anywhere in the frame. This hybrid AF-system can focus with little light, down to -4 EV illumination. The nature of performing autofocus on-sensor means that front or back-focusing issues are not possible with the built-in system, just like any mirrorless. The only reason there is still an option to perform AF micro-adjustment is that Sony offers a special A-to-E mount-adapter that has its own built-in Phase-Detect AF system.
Autofocus on the A7R IV is very decisive. Focusing speed is similar to other high-end mirrorless models. Within ¼s, the A7R IV can look onto most subjects down to moderately low light levels. The system slows down in very dim scenes and at small apertures. A unique configuration option of this camera is called Aperture Drive in AF which selects between always performing AF wide-open, always at the selected aperture or letting the camera decide. The norm for cameras in general is to perform AF wide-open which gives more light and increase the phase-difference of incident rays which leads to faster AF. The Sony A7R IV can focus this way but can also keep the aperture steady to minimize noise. When recording video, the aperture cannot change during filming, otherwise there would be a temporary change in depth-of-field and noise recorded on the audio track of the built-in microphone.
There is a huge number of AF selection modes which support Realtime Tracking. The A7R IV is programmed using machine learning to track faces and eyes specifically, for both human and animal subjects. The result is very steady subject tracking for moving subjects. This system can prioritize one eye or automatically choose which one to track. Sony allows photographers to refine the tracking behavior. One can even slow down tracking speed so that it does not cause sudden movements while recording video.
This ultra-high resolution digital camera is capable of capturing full-resolution images at up to 10 FPS. At that top-speed tough, the A7R IV compromises slightly by only reading 12-bits per photosite. When this is rendered as 8-bit-per-component JPEG images, the difference is lost and the output looks just as good. When capturing RAW data, the drop from 14-bits to 12-bits is small but could be noticed when working with very dark images shot at low ISO. Since only the lowest 2-bits are dropped, this principally affects details in blacks. Starting at medium sensitivities, those two lowest bits are of no use since they get drowned by noise. At 8 FPS and below, continuous drive modes read all sensor data and record 14-bit RAW files.
Four continuous drive speeds are available on the A7R IV: 10 FPS, 8 FPS, 6 FPS and 4 FPS. At all these speeds, the camera can try to autofocus, meter and measure white-balance between each frame. Autofocus will not be performed if the camera or lens is set to MF or when shooting at an aperture of F/11 or smaller. Metering is performed except in Manual exposure mode. AWB happens only if one of the 4 AWB modes is selected. Although, the manual warns that these can become less reliable at 10 FPS. With AF-Priority enabled, continuous drive slows down when autofocus takes too long.
With 61 megapixels in each image, this Sony requires a lot of bandwidth for its Exmor R processor to render images and send them on the UHS-II bus leading to the dual SDXC memory-card slots. When Extra Fine JPEG images or Compressed RAW data is recorded, the internal buffer can hold 68 frames. Compressed RAW files are lossy in that they discard a small amount of information despite still storing 14-bits per-photosite. Uncompressed RAW files are even larger and the internal buffer can only hold 30 of those. When more buffer-depth is needed, the A7R IV offers a 26 MP mode taken from a 1.5X crop which can grab 204 frames per burst.
Controls on the A7R IV are generally responsive. Any turn of a control-dial immediately registers while buttons respond reasonably, although with a slight delay when the camera brings up a menu or list of choices. Once displayed though, navigating a menu is quick. Crucially, the shutter-release and AF-On buttons operate without delay. Shutter-lag for stills is minimal too. The main issue in terms of performance is that the A7R IV tends to stay busy after each shot and ignores controls during a period of time. For single shots, that delay is small but gets long after a continuous burst.
The following measurements characterize the performance of the A7R IV:
- Power-On: ¾ second. Good.
- Power-On to First-Shot: 1 second. Superb.
- Autofocus: ¼-¾s. From very to below average. See below for details.
- Shutter-lag: Instant with very short blackout normally, minimal silently. Excellent.
- Shot-to-shot: Over ½s with mechanical-shutter or slightly above 1/3s with electronic one. Average.
- Playback: 1/3s to enter or exit. Good.
- Power-Off: Instant. Very good.
- Video: ½s delay to start and stop recording.
Although better performance is expected for cameras of this price, some of these below-average numbers are understandable and indicate that substantial processing is required for the output of this sensor. The all-important shutter-lag is really short and becomes barely noticeable during silent shooting which uses a mechanical shutter. In Single-Shot mode, there is a slight pause before the camera is ready to take the next shot. This makes it impossible to achieve faster than 2 FPS without using continuous drive.
The hybrid autofocus system in this mirrorless is very capable. It can focus extremely quickly in bright to moderately low light when shooting at large apertures. With a small aperture, focusing speed slows down considerably in low-light which is why the A7R IV exhibits such variability. This is unusual because the A7R IV focuses at the chosen aperture rather than wide-open, unless Aperture Priority is selected for Aperture Drive. This does not completely compensate for the performance difference due to the small delay necessary to open the aperture. Normally, cameras also preview wide-open so the aperture is stopped-down for the shot rather than opened for focusing.
The Sony Alpha A7R IV is powered by a proprietary Lithium-Ion battery which is rated at 530 shots-per-charge. In practice, the number of shots taken is significantly less. Even with the camera in Airplane Mode, the battery gets drained extremely quickly. During this review, the battery got depleted in less than half this number of shots. There are a few options such as Finder Frame Rate and Display Quality that affect power consumption, as do EVF and LCD Brightness but the difference is unlikely to double battery-life. For a full day of photography, at least two extra batteries are needed.
Without a doubt, the Sony Alpha A7R IV shows an unprecedented level of technological achievement. Its core 61 megapixels Full-Frame BSI CMOS sensor offer the highest-resolution for its size and even exceeds the resolution of most larger Medium Format digital cameras. This Anti-Alias Filter-Free sensor is mounted on a 5-axis image-stabilization system with up to 5½-stops of efficiency which combine to capture sharp details better than all other Full-Frame cameras.
This new sensor paired with a powerful Exmor R processor truly deliver when it comes to image-quality. Their output is suitable for huge 40" x 26" prints with incredible details when captured at low ISO sensitivities. Until ISO 800, the A7R IV shows virtually no noise in rendered images with some light luminance noise visible in RAW files at ISO 800. With low-level noise-reduction applied, very large prints are possible until ISO 3200. Even though ISO 6400 and 12800 show a notable increase in per-pixel noise, the ultra-high resolution of the A7R IV makes it insignificant for typical print sizes.
Image noise and dynamic range have an opposing correlation. At low ISO, the A7R IV captures almost 15-stops of dynamic-range, an impressive achievement for pixels this small. This drops steadily as ISO increases and image noise lifts the black level. Metering is slightly conservative and very dependable, requiring less EC than most digital cameras. Both colors and white-balance can be very realistic, while giving photographers a tremendous latitude.
Autofocus is the other standout feature of this mirrorless. The hybrid system which combines 567-Point Phase-Detect AF and 425-Area Contrast-Detect AF is very reliable and quite sensitive to low-light. Continuous real-time tracking can keep an eye in sharp focus across a huge portion of the frame. This camera can focus extremely rapidly under most conditions with a notable slowdown in low-light when shooting at narrow apertures since AF unusually performed at the set aperture rather than wide-open.
Ergonomics of the Sony A7R IV are generally good. The camera is comfortable to hold, placing keeping a number of controls within easy reach. Its triple control-dials and highly customizable interface allow efficient operation for a number of parameters and features. Unfortunately, this camera leaves its control-dials underused and shows a number of usability issues that slow users down. Many functions remain buried deeply within a very complex menu system.
Build quality of this mirrorless is top-notch. The weatherproof body feels durable all-around, even the LCD hinge seems solid. Buttons are large with a good amount of travel, allowing them to be used with gloves on. The highlight of this camera body is its amazing EVF. This large electronic viewfinder is extremely sharp with its 5.8 megapixels and shows 100% coverage at 0.78X magnification while provided an accurate Exposure-Priority preview. On the other hand, the weakest point of the A7R IV is its very short battery-life due to having to continuously power the 61 MP sensor and 5.8 MP EVF.
Sony delivered an exceptional mirrorless with the A7R IV. Looking at its image-quality and performance, this is a digital camera primary beneficial to landscape and architecture photography. The high-resolution and pixel-density require shooting at relatively low sensitivities which either means taking photos in bright light or with the camera mounted on a tripod. It is also quite capable for studio photography. Travel photographers that carry a tripod can certainly bring back amazing photos with the Sony Alpha A7R IV.
Sony A7R IV Highlights
Sensor-Size: 36 x 24mm
Actual size when viewed at 100 DPI
|61 Megapixels Mirrorless||ISO 50-102400|
|Sony E Mount|
|5-Axis Built-in Stabilization, 5.5-Stop Improvement||Full manual controls, including Manual Focus|
|0.50" Built-in EVF 5.8 Megapixels (0.78X)||Custom white-balance with 2 axis fine-tuning|
|Automatic Eye-Start sensor||Spot-Metering|
|Weatherproof||Hot-Shoe & Sync-Port|
|Built-in Dust Reduction||Stereo audio input|
|10 FPS Drive, 68 Images||Lithium-Ion Battery|
|3840x2160 @ 30 FPS Video Recording||Secure Digital Extended Capacity x 2|
|3" LCD 1.4 Megapixels|
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