Back in September 2018 I did a blog on phone photography, and concluded that while you could get good pictures with a phone, it wasn’t a DSLR. My wife decided to try to use her phone for video, and I recently got a new phone, so I want to talk now about phones and video, and why what you don’t know will hurt you.
Most of my photography, and my wife’s videography, focuses on travel and wildlife. Many people don’t like having to see the world through a viewfinder or on a screen, and so what can be nice about a phone as a video camera is that you can mount it (with an adapter) on a monopod, hold it steady, start shooting, and watch the critter, glancing back to be sure you’re stable and in-frame. But wildlife is often reluctant to approach to just the right distance and stay posing for you, which means that it may be too far away and may be moving erratically. Good DSLRs have zoom lenses and image stabilization, but how about phones?
You can almost always find out if a phone has image stabilization; it’s usually noted in the specifications and often in reviews. Don’t sell this feature short, particularly if you’re shooting in a travel setting. A good optical stabilization system will make video look a lot better, enough to make the difference between good footage and something that requires a bunch of post-processing stabilizing. I’ll get to more on that below.
Let’s start with zoom. As far as I know, nobody yet has a phone that will do optical zooming. Thus, you’re limited to what’s called “digital zoom”. Most good modern smartphones will shoot HD video at 30 and even 60 frames per second. Everyone who’s used a smartphone camera app knows that you can zoom in and out, and with some as much as 8:1. A phone camera is roughly equivalent to a 25mm lens on a full-frame DSLR, so an 8:1 zoom would give you 25-200, which sure sounds good, especially considering how much a full-frame DSLR with that range would cost and weigh. Is it realistic?
Not often, it turns out. One thing I was surprised to find was that reviews of how well a phone camera works in zoom mode are almost impossible to find. An HD frame is about 2 megapixels, and a phone camera is about 12, which means you have six times the megapixel area to work with. The frame is 1920 pixels across, and that means you could stack 4 HD images on a CCD. Intuitively, that would mean you might be able to zoom to 4x without losing HD resolution. But it doesn’t work like that. When you zoom with most phone cameras in video mode, you are taking an HD frame and cropping it, meaning you are blowing up a piece of the image with fewer than 2 megapixels to fill that HD frame. Any zoom at all will lose resolution.
We’ve found in practical use that a decent phone camera and a decent app will shoot video without zoom at a quality level that’s almost indistinguishable from what a DSLR will shoot. Zoom in 2:1 and you can see a clear deterioration of sharpness. At 4:1 you are blurry, and at 8:1 it’s junk.
This can be only the start of the bad news, too. Remember the stabilization issue? Well, images tend to get shakier as you zoom more, because a small camera movement is magnified. You can do stabilization in post-processing with many video packages, but it can cause some significant problems.
When you stabilize an image in a video editor, what you are essentially doing is finding a “crop box” that centers on what you’re trying to get a smooth video of, like a leopard. The box will be 16:9 in size ratio, like an HD video, but its size will be based on just how jiggly the leopard’s position is. If the leopard is fairly steady, moving only about 20% of the frame dimensions or less, the crop box can be only a little smaller than the real frame. The software will shift that little box to stay centered on the leopard, and blow up its contents to 1920×1080, the HD frame. If the box is almost that size because not much motion was experienced, the degradation (which is in effect digital zoom) won’t be too bad. A lot of motion, and it will be very bad. If the leopard goes out of frame, you obviously have to cut the clip at that point.
Since both stabilizing and digital zoom degrade image quality, shooting video on a phone with no optical stabilization is likely to kill quality if you zoom, period. This is why many phone videography tips start by saying “Don’t zoom!”
I have two digital cameras, one (Nikon D500 with a 50-500 Sigma zoom, which is 75-750mm in 35mm terms) for wildlife overall and one (Nikon D750, full-frame, with a 24-105mm Sigma) for wide-angle and most video. Thus, when I needed a new phone, I wasn’t particularly worried about the camera. I wanted a Google Fi phone, and the new Pixel 3a looked good, so I got it. At one point, while getting all the apps installed, I tried the video camera app we use (Cinema FV-5) on the Pixel. To my amazement, the zoom quality was much better. The stabilization helped, but even without it, the image seemed much clearer even at full zoom. With Google’s own with-the-Pixel camera app, it was better still; usable at about 6:1 zoom, where on both my old phone and my wife’s current Moto G6, even 2:1 was problematic. In a flash, my new phone became my wife’s travel video camera!
Well, maybe. The Moto G6 takes a micro-SD card, so we could fill it with storage for video. The Pixel had, after my apps and other stuff, about 30G available to store video, which turns out to be about three and a half hours’ worth using the standard H.264 codec. Fortunately, Google supports the more compressed H.265 on the Pixel 3a, which should give me about 25% more space, but that’s still maybe 4.5 hours. That’s far less than she’d need for a trip, so we need some way of getting video off the phone to store and make room for more.
Google Photo will back up an unlimited amount of video at “high quality”, but you’d need about 200G to store a potentially active trip’s worth, which means buying it. You could also expect the upload of 30G to the cloud to take some time, and you’d have to do it back in camp where you had WiFi. If WiFi happened to be down and the phone’s full, that’s it for wifely video, which is not a good option. A better option would be to dump to a card using the charging port on the phone…if possible.
If you look up how to use the charging port (USB-C on the Pixel 3a) as a USB port to attach an SD-adapter, you find that it works if you have an “On-the-Go” (OTG) cable…perhaps. You can buy what are advertised as OTG cables, but they’re really just a cable with a USB-C connector for the phone and a female adapter to plug in a card reader. No special cable is needed, and you get that adapter with the Pixel. But even with it, there’s still an issue. Android doesn’t support the exFAT or NTFS file systems used for bigger SDXC cards. I tried to use some apps that claim to make these file systems work on Android, but they didn’t work for me.
What does work is a nice SD reader with a USB-C connector. I got this one from Amazon, and it worked right out of the box with the Pixel 3a, both writing to a card (to unload videos) and reading from a card (to move files to the phone). I suspect most good card readers will work as well, but with an important qualifier—the same old file system issue. You need to use a file system Android will read, and if the card is bigger than 32G, the standard system won’t work.
What does work is to get some partitioning software that will reformat the SD card to FAT32, which Android does recognize. You can find free and paid products online. I got AOMEI Partition Assistant and did the reformatting, after which the cards will read/write on the Pixel and of course on my Windows 10 system too. That means I can dump video to one of many 64G SD cards I have, and restore them at home.
Whether this is practical as well as possible depends on the time it takes. If you had to dump the phone during an African game drive, any delay over perhaps 20 minutes could result in missing something. The time it would take depends on the speed of the cards, the speed of the phone writing to them, the USB interfaces involved, and of course, the amount of data. I estimate that the Pixel would hold about 3.5 hours of video in 30GB of free space. How long would it take to dump it all to a card? I couldn’t find any reliable data on this, so a test is necessary. To set one up for yourself, get any large file or directory (a gig of data is nice) and load it onto a card on a PC, then transfer it to the Download folder of the phone. Then, on a clean card, time the transfer back to the PC. Multiply that time by the number of gigs (30 in my case) that you want to transfer in video form, and you have a good estimate of the time it will take. Don’t use a whole bunch of little files; try to have the gig test file made up of a realistic number of files. I took an old set of videos as my baseline to make it as realistic as possible; 13 video clips made up the required gigabyte.
Transferring 1.1G card-to-phone took 1min2sec. The same transfer back to a 200x or faster card took 36 seconds. On a Class 10 card it took 1min41seconds. Based on that, let’s do the calcs. Thirty gig is 27.3 times my test size, so a 36 second transfer for 1.1 gig would mean about 16.3 minutes. The slower card would take 1.68 minutes for 1.1G, which is 45 minutes for 30G. Either is OK if you’re going to use down time to dump phone to card, which means they’re suitable as a means of backing up videography on a phone without an expansion card.
The point of all of this is that if you want to use a phone with a good card reader, and you want decent-speed cards. I tried two different fast cards, and once you get to 200x (30 MB/s) there doesn’t seem to be an improvement in write speed in my setup. You can test your own, but don’t waste your money until you’re sure it will make a difference.
In the field, the key is to check the storage usage on the phone at least as you get close to filling it up, or after heavy use. My plan is to dump the phone to a card at lunchtime unless we do an all-day drive. If you think you might have to dump while traveling, be sure your phone is charged. I carry a big battery pack to charge from if I expect to use the phone (or my wife does!) a lot for video when we’re in the field. DO NOT run out of battery while dumping!
A final word of advice. If you decide to use the H.265 compression to save space, be sure that your video editor will work with it. I’m using Davinci Resolve 16, which does support it (I tested my phone video on Resolve and it was fine). Several other video packages I tested didn’t support it at all, or if they did, they might not edit it properly. Run a test video on your phone, dump to a card, try it on your computer, and make sure it edits, before you commit to field use!