Sony Alpha a7S Compact 4k Camera Review

by on February 4, 2015

Last year, Sony really tried to do something different when they unveiled the first true full-frame mirrorless cameras. The A7S is a follow-up to the A7 and the A7R, a series that began with a simple principle: put a heavy pro-grade DSLR into something just as good with a pro-quality sensor in a lightweight body. Sony brags that the A7S (or α7S, if you want to add that special character) is the smallest full frame interchangeable lens camera. So far, so good, but not quite the best. The Sony Alpha A7S is not exactly a second generation product, but it is a bit of an improvement.

The Good

One great bonus is the fact that it can do 4K video recording via uncompressed HDMI, yet this is also a mixed blessing, as I will soon report on when we talk of The Bad.

In spite of its significantly lower Megapixel count of 12 (number on the other models) the sensor is still the same size as its predecessors, which means that it is good for low-light shooting. The ISO sensitivities range from ISO 100 all the way to a whopping ISO 409,600. This works really well when you are trying to shoot video with dim light. HD video is sharper than the A7 and the A7R as well, as the camera is excellent at shooting in 1080 at 60 frames per second.

The grip has been changed to something larger, allowing the user to hold onto it better. There is also a refined menu system that is easier than past Sony cameras.

As far as shooting video at night, the A7S has near night vision with a direct sensor readout that can capture details in low and bright light.
The A7S also has a completely digital and silent shutter, unlike the loud one of the A7R. This enables a quiet capture mode of your subjects.

The Bad

We mentioned earlier that the grip is large, but the camera is still slightly heavy.

The menu button is on the far left side of the camera, precisely where your right hand is unable to reach it.

Even though the A7S is able to shoot in 4K, you really cannot do this unless you use an external recorder that isn’t even on the market as yet. So far, the only recorders that can be used with the 4K-via-HDMI output on the A7S are ones that are made for studio usage.

The AF (Auto-focus) system does not track moving subject well, making them blurry and imprecise. This can be prevented by stopping down the aperture or using wider lenses, but it pales in comparison to other DSLRs on the market today.

The Battery life for the A7S is not quite good as the user can practically watch the battery meter run down while shooting.

Final Thoughts

It appears that the A7S wants to be both compact which makes the grip more than enough. However, when lenses are stuck on it, you might not feel you have enough of the camera in your hand. There just is no way to have it both ways as yet.

It is very clear that Sony took a risk by giving the A7S less Megapixels, as the A7 has a 24 Megapixel sensor and the A7R has 36 Megapixel sensor. The A7S is at 12 Megapixels, and the rear camera on the Galaxy S5 has more with 16 Megapixels. However, it would appear that the gamble as paid off as having less Megapixels has given way to larger pixels. This enables the camera to be a master of low-light settings, and you could practically take pictures in the dark.

Check the Price of Sony Alpha a7S 4k Camera on Amazon:


Sony Alpha A7S Compact Specs
• Camera Type: Mirrorless
• Video Resolution: Max. 4240 x 2832 pixels
• Photo Resolution: 12.0 Megapixels.
• Sensor Type: CMOS
• File Formats: JPEG, RAW (14-bit ARW 2.3), RAW+JPEG (images), XAVC-S, AVCHD 2.0, MP4 with stereo sound (video)
• Memory Card: MS PRO Duo / SD / SDHC / SDXC
• Lens Mount: Sony E
• Image Stabilization: No
• Connectivity: Wi-Fi, NFC
• Digital Zoom: Up to 2x; 2x Clear Image Digital Zoom
• Display Size: 3.0 inches
• Max. Frame Rate: 60 fps
• Focus Modes: Auto and Manual, 25-point contrast


It comes with a 2x rechargeable battery (NP-FW50), Charger (BC-TRW), body cap, shoulder strap, micro USB cable, and AC adaptor (AC-UD10 or AC-UUD1), with models varying by market.


We have already mentioned the high-quality features of this 12 Megapixel camera with a 35mm sensor, as well as its over-the-top peak ISO of up to 409,600. The XAVC S high bitrate format produces very good video, even if it is not quite possible to really see its 4K abilities.

What really makes it stand out is the ISO sensitivities range, and it is quite grandiose at up to 409,600. This is going to help you really shoot at low-light settings, enabling you to almost see in the dark.

The quiet shutter is also a bonus as you don't have to hear that huge "CLICK" that comes with most DSLRs.

Overall Performance

You may not have the 4K without anything external, but at least you have a decent and lightweight 4k DSLR. There are not a lot of cameras that will be able to give you pictures of this quality, and it might be worth your money just to how great of a photographer that you can be.


What we have here is a 12.2 effective Megapixel 35 mm Exmor CMS sensor paired with a BIONZ X image processor. We have already discussed the ISO 100-409,600 range, and it has 15.3 stops of dynamic range. The dynamic range has been kicked up to 1300 percent thanks to the power of S-log 2 gamma.

It also incorporates a “direct pixel readout” using the entire width of the full-frame image sensor without line skipping or pixel binning, allowing the A7S to read and process data from every one of the sensor’s pixels.

We have already mentioned what the A7S can do in low-light, and It also has a Fast Intelligent AF, which means it works in light as low as EV -4. One of the ways the A7S can do this is using a new-generation RGB color filter, and I’ll just let Sony say it: “light concentration technology and photodiode expansion technology delivers unprecedented high sensitivity and low-noise levels with high dynamic range in every light condition from severe low light to bright sunlight. Ghosting and flare have been minimized by applying an AR coating on the surface of the glass seal over the image sensor, further contributing to the high image quality on the a7S”.

We have already discussed the possibility and limitations of its 4K video ability, but in XAVC S video mode, the A7S can output uncompressed QFHD 4K video (3840 x 2160 resolution) in 8-bit 4:2:2 to an optional external 34d party 4K recorder via the HDMI.

It also has a 2.4M dot XGA OLED Tru-finder Viewfinder that uses the same 3-lens optical system used in Sony’s flagship a99. This Viewfinder will give you 3 times the contrast of the a99, as well as a wide viewing angle and 100 percent frame coverage. The 3.0 inch (1,229k dots) Xtra Fine LCD display can also swing up to 84 degrees for photographing over crowds, or swing down up to 45 degrees for shorter subjects. The viewscreen also has WhiteMagic technology that can allow for visibility even in bright sunlight.

It has a Multi-terminal interface shoe that is compatible with Sony’s XLR Adaptor microphone kits like the XLR-K1M, as well as other models under development, giving it a professional microphone system like no other.

Since it is an interchangeable lens camera, it can be used with A-mount and other lens systems with the proper adapter. The E-mount lens system is good for all kinds of situations like video.

It is also easy to connect the A7S to smartphones with Wi-Fi and NFC controls. Sometimes all you need to do is just touch your smartphone to the camera, and you can have a shutter release that is controlled by a smartphone.

Image Quality and Resolution

The video resolution is the following: XAVC S Full HD - 1920 x 1080/[email protected] Full HD - 1920 x 1080/[email protected] Full HD - 1920 x 1080/[email protected] HD - 1280 x 720/[email protected] *Class 10+ SDXC memory card is required for recording in XAVC S AVCHD™. We have already discussed that it is about 12.4 Megapixels, with an emphasis on “Mega” meaning “large”.


It costs about $2,499.99 on Amazon.

Check the Price of Sony Alpha a7S 4k Camera on Amazon:

The Not So Great

When we reviewed the Panasonic GH4 4K Hybrid Camera, we put its $1,697 price in the “not so great” category. This one costs $2,499.99, and the lenses will also set you back.


• Good for 4K
• Extremely good ISO range at 100-409,600
• Large grip
• Very good in low-light situations
• Silent and digital shutter


• No way to see 4K footage well, just yet
• Menu button location
• AF misfunctions on moving subjects
• Drains battery very fast

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Bottom Line

If you are looking for a DSLR with a light weight, the A7S is your camera. It is full of a lot of features that are not on most DSLRs, and if not for that 4K external issue, it would be ideal.

Check the Price of Sony Alpha a7S 4k Camera on Amazon:

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