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Smartphone Filmmaking: Saving Battery Life and Storage Space

Smartphones are incredibly useful for documentary filmmakers, but how can you keep shooting with limited battery life and storage space?

Top Image via Photo-Nic.

Smartphones are becoming more serious contenders in documentary filmmaking with each new iterationThey’re small, lightweight, and packed with tons of useful features — and most newer models can record in 4K.

There are also plenty of rigs, apps, lenses, and adapters for smartphone filmmakers. The Helium Core, for example, is a chassis for customizing your iPhone camera rig. Combined with Moondog Labs lenses, the end result is very appealing and costs only a fraction of a DSLR rig. Take a look at the results.

However, there are a few challenges to using a smartphone as a primary camera for a documentary shoot. Specifically, how do you preserve battery life and storage space? With some preparation and few tweaks to your production schedule, you can address these limitations.

1. Clearing Storage Space on Your Smartphone

Smartphone Filmmaking: Saving Battery Life and Storage Space Apps
Image via Saulo Mohana.

Back up and clear existing photos and videos

The day before any shoot, I’ll back up all of my photos and videos on an external hard drive to clear as much space as possible for my incoming media. My primary smartphone camera is my 128 GB iPhone 6s Plus. At any given time, I have close to twenty GBs of photos and videos that I clear regularly before filming. That’s about 15 percent of total storage space, or about an hour of 4K video.

So I generally make it a habit to free that space up for incoming media — you should too.

Clearing nonessential apps

This is completely optional, and it really depends on your available storage space. However, if I’m prepping for an intense shoot, I’ll take some time to clear any nonessential apps from my phone, especially if I don’t use them regularly.

2. Preserve Battery Life with a Portable Charger

Portable chargers are essential for smartphone filmmakers. I usually like to have at least two chargers on set. By bringing two, I can always have one on the camera and one charging, allowing me to film constantly. I personally use the Zendure A2 Portable Charger, but there are plenty of battery packs out there, ranging from cheap to very expensive. 

3. Carry a Laptop and External Hard Drive

Smartphone Filmmaking: Saving Battery Life and Storage Space Laptop
Image via Radek Grzybowski.

While some Androids will allow you to capture media on MicroSD, the iPhone captures media internally. This means that once we fill the library, we can’t remove the phone’s memory, so we’ll need to dump the media. Bring a laptop and an external hard drive with you to the shoot. (If you’re shooting on MicroSD, don’t forget an adapter.)

I like to have two smartphones on set, so I can continue shooting without stopping for fifteen minutes to dump media.

With the iPhone 6s Plus, simple shoots only require a single media dump. The iPhone has insanely efficient media storage. Here are the estimated numbers that I pulled based on technical specs provided by Apple (and assuming marginal space reserved for essential apps and iOS).

iPhone 6s Plus and 7 Plus 32 GB Record Time   128 GB Record Time 256 GB Record Time
720p at 30 fps  8 Hours 20 Minutes   35 Hours 70 Hours
1080p at 30 fps   3 Hours 50 Minutes 16 Hours 10 Minutes 32 Hours 30 Minutes
1080p at 60 fps 2 Hours 50 Minutes     12 Hours 24 Hours 10 Minutes
4K  at 30fps 1 Hour 25 Minutes     6 Hours 12 Hours 5 Minutes

4. Record Interviews Ahead of Time

If you’re forced to record the interviews and B-roll together (e.g., talent has limited time), don’t record a full interview. It will take up a massive amount of space on your phone. You can pre-record the talent’s voiceover, then craft the story and create a shot list. 

Pro-tip: Use your voice memo app to record your talent’s audio, then cover the voiceover with your B-roll.

Bonus: Gear and Apps

Here’s a look behind the scenes of a short film I shot on an iPhone 5c. You’ll get a glimpse at my setup — and a few more tips from the set.

If you are looking for some filmmaking apps for your smartphone, check out these posts:

What smartphone gear do you use? Let us know in the comments.