The iPhone 4 as a Filmmaking Tool
I was very excited when I refreshed Engadget for the 283rd time on the morning of the WWDC and officially knew the new iPhone would be getting 720p video recording. I knew it wouldn’t come close to our 7D, but it might actually be useful for something. Who knows. So no sooner than I got my “phone” in the mail, I had it covered in gaffer’s tape, attached to our 7D and Steadicam Merlin.
The iPhone 4 has a fixed f/2.8 aperture and a relatively large 3.85mm lens (which seems to be approximately the equivalent of 35mm on a crop sensor or 56mm on a FF). It has an automatic, variable shutter speed between 1/15 and 1/10000; an automatic ISO of around 80-1000; and the sensor is 1/3.2″ and has some new backside illumination tech to capture more photons (although, in low light, it’s still noisy as heck). Oh, and it records 1280×720 footage at 30fps (just like the original 5D Mark II firmware, it’s 30, not 29.97). The bitrate is about 10 mbps (not bad) and the audio is a low mono 66 kbps at 44.1 kHz. Here’s a good article with more comparisons and statistics, if you’re interested.
To adjust the exposure (and focus at the same time) you just tap an object in the frame. It’s pretty handy, I sometimes wish our 7D had a feature like this. You can focus in video mode, even during recording (it pulls focus way too fast to do any racking, though). The auto exposure and focus sometimes kicks in during recording automatically if too much changes in the scene (annoying).
Day 2, I wanted to really test the quality and see how far I could push the phone so I went out on my own and shot a little Bokake*. I failed. I realized because the rolling shutter is so apparent, you absolutely have to have good stabilization. Any sort of movement that is too rapid causes distortion and it just looks awful. You also need to pay attention to what is going on in a scene. Again, if you move too quickly, the auto shutter and ISO and focus will kick in and you’ll notice it. Day 3, I borrowed my sister. I put on my rollerblades and had her push me at walking speed. Static shots work the best, but eventually I got the hang of it and was able to get some decent moving shots (note the basketball backboard POV shot in the video below). These shots are graded. I figure if I’m to be putting this to the test, I would use it like a normal camera and go through the whole process, CC and grading included. One thing that really helped was conforming the iPhone footage to 24p. 30 fps looks ugly to me, so pretty much anything I shoot on my phone will always be conformed. It’s really subtle slow-motion and definitely helps smooth out the movements a bit.
Please watch in 720p, fullscreen if possible.
So, do I believe this is a viable filmmaking tool? No. I think without at least some real control over exposure, you would have to make some huge compromises in the way you tell your story. But that isn’t to say the iPhone is useless in filmmaking. Having such decent quality in your pocket will make it that much easier to frame up shots, scout locations, and even document the process. It’s a great little camera.
Finally, since I had my iPhone connected to my 7D (mostly for added weight), I recorded both at the same time for fun. Please please please take note that I was mainly focusing on the iPhone and didn’t really check the exposure or even the focus in some shots on the 7D so don’t take this comparison to heart. It wasn’t my intention to shoot video with the 7D at the same time, but here it is anyway: