PocketMeter Pro: Bill Manning Built the Light Meter App He Wanted to Use

There are already plenty of light meter apps, so if you're going to make another one, there should probably be a reason.

Bill Manning had one.

Bill is a photographer and cinematographer, the guy behind Studio C-41 and one of the founders of Atlanta Film Co. His problem was pretty simple: he wanted one meter that made sense whether he was shooting still photography or motion. Still photographers normally think in shutter speeds. Cinematographers often think in shutter angles. Bill wanted both without bouncing between different tools.

That became PocketMeter Pro, a light meter app built around the camera that's already in your pocket.

As of this writing, PocketMeter Pro is in public beta on iPhone and requires iOS 17 or later. The current TestFlight beta is free through September 18.

One meter for stills and motion

The original idea wasn't much more complicated than that.

Bill wanted to meter a scene and get the information he needed for still photography, then switch over and get useful cinematography settings like shutter angle without leaving the app.

PocketMeter Pro reads reflected light using the iPhone camera. In photography mode you can work with shutter speed, aperture and ISO. In Cine mode it switches over to things like shutter angle, iris, frame rate and ND. The current version also includes tap-to-spot metering, false color, exposure preview, screen recording, geotagged exposure logs and LiDAR distance measurement on supported iPhones.

That's a lot more interesting to me than simply duplicating the display of a traditional handheld meter on a phone screen.

Bill doesn't really see it as a traditional light-meter replacement anyway.

He sees it as another tool.

If your regular meter is sitting in your bag with dead batteries, or you didn't bring it at all, the phone can be the backup that's already with you. For students, there's another obvious advantage: a dedicated professional meter can cost hundreds of dollars. A phone-based tool gives somebody learning exposure another way to start understanding what the light is doing without immediately buying another piece of hardware.

But can you trust it?

Obviously, none of the features matter much if the exposure reading is wrong.

Bill tested PocketMeter against his own Sekonic and found some variance. That wasn't especially surprising; different phone sensors can disagree slightly, and Bill was seeing differences on the order of roughly a third of a stop.

His solution was to add a trim adjustment.

If you already own a meter you trust, you can compare the two, figure out whether PocketMeter is consistently reading a little high or low, and apply a positive or negative EV correction until the app matches your reference meter.

I like the thinking here because it's practical. The question isn't whether every iPhone sensor on Earth produces exactly the same number as every Sekonic. The question is whether you can establish a predictable meter that you trust.

Bill also told me that several working directors of photography have stress-tested PocketMeter and have been happy with its exposure accuracy.

Again, he isn't positioning the app as the thing that makes your existing meter obsolete. It's more like calibrating another instrument in the kit.

Beta testing actually changed the app

PocketMeter started as what Bill calls an MVP—a minimum viable product. The point was to get something functional into photographers' and cinematographers' hands and see what broke, what was confusing, and what was missing.

A lot changed.

Accessibility was one area Bill admits he hadn't considered enough at first. Beta testers brought up problems with how they were interacting with the interface, which led to changes intended to make the app easier to use.

Other feedback was extremely specific.

Someone shooting older motion-picture equipment might need a shutter angle Bill hadn't originally included. A Bolex, for example, may use a 144-degree shutter. So that went in.

The controls evolved too. Values can be tapped directly, or adjusted more precisely by holding and dragging. According to Bill, he's already gone through 34 versions. Visually, the first version and the current one may not look radically different, but a lot of the refinement is in how the app actually behaves when you're using it.

That's generally what I want to hear about a photography tool being beta tested. Not that somebody moved a button three pixels to the left, but that photographers went out and used the thing and came back with oddly specific complaints.

Oddly specific complaints are where useful tools come from.

False color might be the sleeper feature

Bill's favorite feature is false color.

Cinematographers will already know what this is. Instead of looking at a normal image and trying to judge brightness by eye, false color maps different exposure levels to colors. PocketMeter's current implementation, for example, identifies middle gray, skin exposure and clipped highlights relative to the exposure settings you've dialed into the app.

Still photographers may be less familiar with it.

That's actually part of what Bill finds interesting. He's seeing photographers start to understand how false color can help them visualize where different areas of a scene fall instead of only getting a single meter number.

You can see where you're approaching clipped highlights or where shadow information is disappearing. It isn't magically turning an iPhone into a cinema camera or changing the limitations of the phone sensor, but it gives you another way to think about the distribution of light across the frame.

PocketMeter also has an exposure-preview mode, which Bill likes for similar reasons. It can give you a visual idea of what is going to fall over or under even though there are obviously limits to how closely an iPhone preview can represent whatever camera and film or sensor you're actually using.

It does things a regular meter can't

One of the more useful ideas behind PocketMeter is that it doesn't have to imitate a handheld light meter in every respect.

The phone can do other things.

You can save a still with the exposure information recorded on it. The app can geotag that frame so you know where the reading was made. You can screen-record while scouting a location. The current app can save logged readings into Photos with exposure data attached, and the location can later be pulled up on a map.

Bill is also working on ways to make that information more useful. Planned ideas he discussed with me include 2x or 4x zoom to narrow the metered area and recording the exact spot you tapped when making a spot-meter reading, so you can later look at the saved frame and know precisely what part of the scene you were measuring.

For cinematographers, he also wants a cleaner screen-recording view with exposure controls that can collapse when they aren't needed.

Those are good examples of where this stops being "Sekonic, but on an iPhone" and starts taking advantage of the fact that the meter is also a camera, GPS device, screen recorder and computer.

Android and the dreaded subscription

Right now PocketMeter Pro is an iPhone app. Bill says an Android version is being worked on, but Android creates a much bigger hardware-testing problem because of the number of different phones and camera systems the app has to support.

He also has very definite opinions about how he wants to sell it.

Bill's plan is a one-time purchase rather than a subscription, with future updates continuing for owners of the app. He told me plenty of people advised him to go with the now-familiar subscription model.

His response was basically: why?

He hates subscriptions.

I suspect a lot of photographers will understand that position without much further explanation.

The longer-term idea is to build additional applications for photographers and cinematographers and turn them into a family of tools rather than trying to extract another monthly payment from the same meter.

Another tool in the bag

The thing I find most sensible about PocketMeter Pro is what Bill isn't claiming.

This isn't being presented as the death of the dedicated light meter.

If you already own a Sekonic that you've trusted for years, great. Keep using it.

PocketMeter is intended to be the thing that's available when the other meter isn't, the inexpensive meter a student can learn with, the scouting tool that records more information than a traditional meter can, or simply another way of looking at exposure.

And because Bill shoots both stills and motion, it doesn't treat those as completely separate worlds.

That's really why the app exists in the first place.

One photographer needed both sets of numbers and got tired of switching tools.

So he built the tool he wanted.

Links:

• PocketMeter Pro: https://pocketmeterpro.com/
• PocketMeter Pro Press Kit: https://pocketmeterpro.com/press.html
• Bill Manning / Studio C-41 on Instagram: https://www.instagram.com/studio.c41/
• Atlanta Film Co. on Instagram: https://www.instagram.com/atlantafilm.co/