The Sony A7s 4K Guide (Part Six): Power and Audio

In Part Five we looked at the external recording and data wrangling options of the Sony A7s. In this part we’ll cover audio and power requirements and solutions.

Sony A7s Vertical Grip

First let’s look at audio.

Audio

The Sony A7s has a built-in microphone and built-in speakers, both of which I wouldn’t use even for home movies (are you going to subject your loved ones to terrible audio?).

The camera has two ports for audio:

  • 3.5mm stereo jack for a microphone, mic level
  • 3.5mm stereo jack for headphones

 
The formats being recorded are (24-bit 48 KHz):

  • XAVC S:LPCM 2 channels
  • AVCHD: Dolby Digital (AC-3) 2 channels
  • MP4: MPEG-4 AAC-LC 2 channels

 
There is always a limiter applied to audio, regardless of the setting of levels. You can monitor levels using the back of the LCD. I can only comment on the actual quality after testing it in the field, though at this point I’d say it is on par with standard DSLR audio. It can be used for event-based work, as well as ENG, etc. For higher quality work, I would stay away from the internal audio of the Sony A7s.

External Audio

Sony provides an XLR adapter for the Sony A7s, the XLR-K1M, which retails for $798 (includes the ECM-XM1 shotgun microphone):

XLR K1M

The adapter allows you to connect up to two phantom powered XLR microphones with both mic and line level ability. It also gives you direct control over gain and levels with tactile controls similar to those found on ENG video cameras. The power consumption will be too minor to affect recording times. The two disadvantages are:

  • It must be connected to the hot-shoe adapter, which makes it difficult to mount the Shogun in the base configuration. Also, the hot-shoe mount is the weak link and is susceptible to damage over time.
  • It is too expensive.

 
At this time, I cannot recommend the XLR-K1M for the Sony A7s. Instead, I strongly recommend the Tascam DR-60D instead. It will fit under the camera body via the tripod mount, where the controls will be easily accessible. And, it retails for less than $200.

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Power

The Sony A7s comes with an AC to USB adapter (AC-UB10) which also charges the battery.

For a more ‘regular’ AC adapter, you will need to purchase the AC-PW20 ($80 for original Sony, about $20 unbranded). The camera does not have a DC port, and the adapter has a battery attachment instead.

The camera comes with a charger (BC-TRW, which retails otherwise for $48) and two batteries (NP-FW50: 7.7Wh, 1080mAh, $40 for original Sony, about $5-7 for unbranded). Some of the unbranded batteries, like this one for $7, are rated at 2300mAh, or twice the capacity. Be extremely careful before using unbranded batteries. I’ve generally had no problems using them, but you must buy after reading many reviews. Don’t blame me if something goes wrong!

You can also extend the recording times by using a vertical grip, like the original Sony VGC1EM, which sells for $298. You get to use two batteries at the same time, and it might help you handholding the camera as well. The negatives are:

  • It adds weight, almost double with two batteries
  • It might interfere with the mounts on the lens adapter, especially the Metabones adapter.

 
How much battery life does the NP-FW50 provide? According to the official specifications, here are the ratings:

  • Approx. 55 min with viewfinder, approx. 60 min with LCD screen – if you also zoom while recording
  • Approx. 90 min with viewfinder, approx. 90 min with LCD screen – if you are not using any functions except recording.

 
In real world use, one can estimate about 60 minutes (one hour) of usable battery life in video mode, using a 1080 mAh battery. The viewfinder draws more power than the LCD.

What about charging time? The stock charger takes about 220 minutes (just shy of four hours) to charge one battery! Now that’s a problem. Therefore, I recommend getting a Wasabi Charger+2 battery kit for $26.99. It will also charge the stock batteries. Even though the Wasabi is rated at a higher energy level, you get about the same or slightly lesser battery life. For professional use, I recommend getting two Wasabi kits to supplement the Sony kit. You’ll end up with three chargers and six batteries. Consequently, you can also use dual chargers.

Atomos is probably coming out with a power solution that encompasses the Shogun recorder as well as the camera, though the price might be in the $300-400 range (don’t hold me to that!). The Shogun takes a Sony NP-F970 (6300 mAh, retails for about $120) battery which will give it about 2.5 hours of life. You could get a Wasabi kit with two batteries and a charger for $84 instead and that would be the route I would take.

Of course, you could power up an entire rig with Anton Bauer batteries as well, but we are yet to see adapters from the same. At the moment, you are at the mercy of internal batteries.

In Part Seven we’ll look at tripods, rigs and the cost of putting together a video kit for the Sony A7s.