Cellphone Light Metering Apps
Useful tool or gimmick?
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For film photographers, a light meter can be a critical tool. But for the hobbyist or amateur, modern light meters can be expensive and cumbersome and batteries are no longer available for the older analog light meters. Luckily it turns out that you are already carrying a light meter in your pocket, i.e. a cellphone. A cell phone application is the perfect solution to any film photographer's exposure woes. These three apps range from $5 to completely free, and require no special equipment other than the smart phone already in your pocket.
When putting together my article about shooting without an in-camera light meter, I realized that a few years back I had downloaded three iPhone metering apps, but had only been using one. I always used the one with the more recognizable icon and completely forgot about the other two. Perhaps I've been missing out on a better app and as such, have decided to give you a review of all three.
These are the first three photography related apps that appear in the iPhone app store when searching "light meter" and are either free or less than $10. The criteria I will be judging them by include:
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User friendliness
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Features
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Accuracy
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Price
Light & Exposure Meter
by Paul Buhkonov/Measure Photography Light
Price: FREE
Pro Version: $4.99
iPad app available
Features
White Balance Reading. A cool feature, yet not terribly useful for film photography. Perhaps if you are shooting with color filters, then knowing this number can assist in your decision making process. This could be more useful for digital photography, but I shoot in raw and my Nikon D810's auto WB is extraordinarily accurate except in extreme cases, which I doubt this app algorithm could match. I did not put the two head to head on color balance during my testing.
Speed, Aperture, and ISO scroll wheels. The design of this feature is really where this app shines. Two of the settings can be locked with the other variable. The buttons are easy to use, even with clumsy fingers. Unlike the numbers overlaid on the areas of your photo, the white on black here is easy to read and understand. This app accomplishes this important component the best of the three tested.
Hold Button. At first I doubted the necessity of having a hold button, but as I tested the apps, I came to enjoy this feature. It basically freezes the sample photo and the settings so you can capture what you need and then move the phone to read the results without it constantly taking new readings. This makes taking a screen shot a whole lot easier as well. With the other two apps I kept messing up screen shots, because I would move the phone while pressing the buttons.
Log. The Log feature does virtually the same thing that the Hold button does, but makes for an even easier way to save the metered data. It displays all the settings including location which is nice. From the Log page you can save it as an image or file, and even send as a text email or to social media. I wish that it saved the logs in app as well, but it does not seem to have this feature. When shooting film I often take a note book with me to write down my settings for each shot, however, I usually get involved with the shooting and forget to keep taking out pen and paper to record my settings. This can be a way to quickly meter and save settings for later that avoids all the hassle.
Rear facing camera toggle. As far as I can tell this is the only one of the three that has this feature. Not an extremely necessary feature, but unique to this app all the same.
Target. Unfortunately you cannot move this center target, and from my brief testing it appears that the app spot meter is at or heavily weighted to the center target. Therefore, when trying to evaluate the lights and shadows in your scene, you have to move the phone around.
EV number. It displays the EV for both the ISO you have selected and for the base 100 ISO. To be honest, I don't pay much attention to this when shooting film, and on my digital camera I use EV to over/underexpose a shot vs finding the correct exposure.
Settings
The settings page on this app is not extensive, but sufficient.
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The ability to turn off the white balance reading and other data.
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An exposure correction feature can be turned on for finding the settings to over/underexpose a shot. This can be useful, if you've been shooting in low light and are going to push your 400 ISO film to 1600 and the next day you still have a few shots left in brighter light; this feature can help you underexpose by a couple stops.
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you can select shutter, ISO, and aperture in increments of full, half, or third's of stops. This helps match the settings of the app to your actual cameras manual settings.
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Toggle on or off location display in Log page.
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Purchase the Pro Version for $4.99 to remove ads.
Paid Version:
For $4.99 the pro version has no additional features, but will remove ads from the app. The ads on the free version include standard banner ads at the bottom of the screen along with extremely annoying full screen pop-ups that appear about every thirty seconds, rendering it almost unusable in my opinion. I recommend trying the free version to see if it meets your needs and then purchasing the pro to remove ads.
Cons:
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Free version's ads are extremely irritating and constantly interrupting the use of the app
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Pro version doesn't add any additional features
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Pro version is the most expensive of the three apps
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Cannot touch the screen to 'spot meter'
Features
Lux - Professional Light Meter for Film Photography
by Avicora
Price: FREE
Pro Version: NONE
iPad app available
Current Settings. The current settings are displayed at the top of the screen; unfortunately, there is no indication of which setting is locked and which is variable.
Setting selection. The settings are selected at the bottom of the screen. The lower horizontal dial toggles between Compensation, ISO, Aperture, and Speed. The dial just above that allows you to select the specific setting in each category. You need to set ISO and compensation first, then select Aperture or Speed and it will meter for the other, i.e. if you have speed selected at the bottom it will determine the required aperture and visa versa. The scroll wheels are a bit clumsy and it is not exactly intuitive which one you have locked and which setting is variable.
Touch for Spot Metering. The app allows you to tap on an area of the scene to expose for that location in the photo. This is an extremely important feature that comes in very handy when shooting in high contrast, high dynamic range conditions.
Exposure Guidance. This feature can be turned on or off and will alert you if the scene cannot be reasonably exposed, or the settings you have selected risks under or overexposing.
EV number. EV number display can be turned on in the iPhone settings. It will only display the EV for the ISO you have chosen.
Settings
The settings page offers a few options for configuring the app.​
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You can select aperture, shutter, ISO, and compensation in increments of full, half, or third's of stops. This helps match the settings of the app to your actual camera's manual settings.
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Mode offers three choices; prefer underexposure, prefer overexposure, or closest match so that when the metered light falls between two exposures, it will know which one to choose. I tested the app with it on closest match, but perhaps I would use "prefer overexposure" when shooting film and "under exposure" when shooting digitally.
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Exposure guidance alerts can be toggled on/off.
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The Help menu is fantastic on this app. There is a FAQ section that will answer most questions any user would have as well as a pseudo user manual with clearly written instructions on how to use the settings and features.
Pros:
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Completely free
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No advertisements
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Ability to touch screen for spot metering selected areas
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Rotates for use in landscape or portrait orientation
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Good help page for instructions on use
Cons:
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Settings dials are clumsy and sometimes a bit difficult to use
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It can be confusing as to which settings are variable and which are locked
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Limited amount of extra features
Features
myLightMeter
by David Quiles
Price: FREE
Pro Version: $3.99
iPad app available
Shutter and Aperture Settings. This app is designed to look and function like an old analog light meter. After pressing the measure button, the inner wheel will spin and line up the proper shutter speed with aperture setting. Unlike the other apps where you can only view one choice at a time, this one allows you to immediately know the correct exposure for aperture/shutter combinations over the entire range of your cameras settings
ISO selection. An easy to use dial allows you to scroll in the ISO for the film you are using, automatically updating the results of your measurement. The available ISO range is 50-3200.
EV number. EV number is displayed in the corresponding window on the standard scale of base ISO, with -2 being a very dark scene and 22 being the brightest scene.
Viewing window. The viewing window is small, especially when compared to the other apps. However, after using this light meter for awhile, I would say it is adequate and leaves room for the much more important shutter and aperture values wheel.
Measure Button. To get a meter reading, simply put your subject or area of your composition in the viewing window and press 'measure' and the wheel will then spin to display the correct exposure values. The wheel will then hold these values, even if you move the phone away from the subject (although the viewing window will still maintain a live camera view of where the phone is pointed).
Settings
There are no adjustable settings in the free version of this app.
myLightMeter Pro
The Pro Version still has the classic mode and usability as the free version, but offers another mode with a ton of added extra features.
Classic Screen. With the pro version you can still use the classic meter. On this screen there is one new feature which is the addition of a toggle knob for incident vs reflective light readings. Click on the word Pro at the top and you will be taken to the extended world of iPhone light metering capabilities that the Pro version offers.
Hyperfocal Distance. When using one of your preset lenses, the hyperfocal distance for that lens will be calculated along with the light metering measurement, which is great for an amateur like me who struggles with zone focusing. When I look at the example here I know that at f8 I should be in focus, if I focus to infinity, as long as my subject is further than 4 meters away.
Features
Read File. This allows you to pull up any photo from your phone (that has exposure meta data) and read the setting values. It works perfectly for all the photos I've exported from Lightroom.
Average. The pro version lets you spot meter by touching areas of your scene, and better yet it will take an average of several readings when this feature is toggled.
IR. Toggle this to calculate the hyperfocal distance for infrared photography. (This is straight out of the instructions, as I cannot speak further on this topic at this time.)
Mode. This button will switch between incident and reflected light. So far, all these apps are using reflected light, i.e. when light hits the scene your phone is pointed at and different amounts are then reflected back; this is the light your phone camera's sensor is picking up and measured by the meter. On this app you can place a diffuser over the lens of the 'selfie camera' for accurate readings. Incident light will provide a more accurate reading, because it is only reading the light falling on to your subject and unlike reflected like, it isn't affected by the color or shininess of your subject.
Exposure Compensation. Moving the arrow left or right of zero will adjust your values for under/overexposure in increments of 1/3 stops.
Lens Presets. Up to five lenses and their settings can be stored in the app. This helps the hyperfocal distance calculation as well as placing a max/min aperture and shutter speeds. Therefore, when using my 80mm Yashica with a max aperture of f3.5, it won't tell me to open it up to 1.4 in low light.
Aperture, Speed, and ISO selection. Is now in the slot machine scroll wheel style, where two of the settings can be locked and the other variable, which will rotate to the proper exposure setting when pressing the measure button.
Spot Metering
The pro version allows for spot metering, which is a must have in my book. Clicking on the viewing window will bring up a larger viewing screen with a metering matrix visible. From here you can touch areas of the scene to spot meter.
Settings
The settings on the pro version of the myLightMeter app is quite extensive and includes:
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ISO Lock
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EV for selected ISO vs just 100 ISO
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Meter using full stops or 1/3 stops.
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Calibration for using reflected or incident modes
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Setting max/min speed and aperture limits for general use
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Storing 5 lens presets
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Switch the hyperfocal distance and EV readings to display as numerical values rather than as needle readings.
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Disable the functions of the volume buttons to allow for music to continue while using the app.
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Tilt phone to display preset buttons on the smaller screened phones.
Clicking on the top of the screen while in pro mode, will bring up a user guide with information about the function buttons.
Pros:
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Free version has an old style wheel that allows you to see all correct exposure settings at one time.
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Free version is very easy to use and provides quick understandable results
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Paid version is affordable at $3.99
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No ads on either version
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Paid version has very accurate spot metering
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Paid version has a ton of features that the other apps don't offer
Cons:
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​Other than taking a screen shot, there is no way to store your results.
Accuracy Test and Results:
To test the accuracy of the three apps, I took readings on a high contrast scene and then took a photo using the apps suggested settings. Because the iPhone camera's aperture cannot be changed and the iPhone uses computational algorithms to create the best exposure within its limitations, an iPhone photo will not provide accurate test results. With this in mind, I decided to use my Nikon D810 DSLR in manual mode to test the accuracy of the light meter application's suggested camera settings. I selected ISO 100 and f8 as the control settings and let the applications choose the proper shutter speed. The results you see here were uploaded and exported from Lightroom, but NO ADJUSTMENTS were made to the photo prior to export.
Metering the scene as a whole, the apps tend to prevent the sky from blowing out; however, it sacrifices detail in the shadows. The Light and Exposure meter, and MyLightmeter apps chose 1/500th sec. On the apps, it looks like a properly exposed scene, but in the Nikon photo you can see that the shadows are extremely underexposed.
Light & Exposure Meter
My Lightmeter
Nikon DSLR Results
The Pro version of myLightmeter and the LUX app choose speeds 1 stop lower at 1/250th sec. Still aiming to preserve the sky, but the shadows are a bit lighter. This would be no obstacle to correct for digitally in lightroom, but tricky in a darkroom. Darkroom guru, Alan Ross, once taught me that the best policy when shooting film is to expose for the shadows, because it is easier to add time burning in the sky than to subtract time for dodging shadows. I believe the same goes for digitally editing negatives. It is easier to make a photo look good by darkening; but, once you start trying to pull detail out of the shadows from scanned film, the photo becomes milky looking.
Nikon DSLR Results
My Lightmeter Pro
LUX
Realizing that the light meter apps were determined to preserve the sky and sacrifice the shadows, I decided to take a reading of the shadows. The Light & Exposure meter and the myLightmeter app, do not allow for 'spot' metering, I had to move the phone and 'recompose the shot' to get an accurate reading of the shadows. Because the bright sky was still in the corner of the shot, the meter was still influenced by the sun; it prioritized the shadowed area that took up most of the screen. This resulted in a 1/125th sec shutter speed, and the best exposure of the four tests. Based on this information, when using either of these apps to meter for film photography in a high dynamic range situation, I would compose the meter to include a minimum of 4/5ths shadow area and a small amount of light area to get the best results for my original composition.
Light & Exposure Meter
My Lightmeter
Nikon DSLR Results
The myLightmeter Pro and LUX apps allow for you to press on the screen and take a reading for a specific spot. Therefore, when metering for the shadows, it allows for a setting which would completely overexpose the sky, yet give the best exposure for the selected area. Both these apps came up with a 1/30th sec shutter speed which preserves every bit of the dark areas and completely blows out all the light areas. The metering for these two apps for the bright areas was 1/250 sec and for shadows was 1/30 sec; a four stop of light difference. In practice you can meter for both and then choose a setting in between that will favor the look you need. In this case when shooting film, based on the information from these apps, I would choose a 1/60th sec shutter speed knowing that I will get enough detail in the shadows and can burn the sky back in during post processing or printing.
Nikon DSLR Results
My Lightmeter Pro
LUX
Conclusion and My Pick
All three of these apps offer a great alternative to carrying around an expensive, bulky light meter. They come especially in handy when your film camera lacks a light meter and the scene is a bit too complex to automatically apply the standard sunny 16 rule. Each app has its strengths and weaknesses, but if you can only go with one, I believe myLightMeter is my first choice. While the free version of myLightMeter is good, the pro version covers its one weakness, i.e. spot metering. In other words, the myLightMeter Pro is worth every penny of the $3.99 at the iPhone app store.
As for the other apps, Light & Exposure Meter's greatest strength is its ability to log and store the settings. I will use it instead of the myLightMeter when running experiments where it is important to remember camera settings. However, the Light & Exposure Meter does not allow for spot metering which is a deal breaker when scenes start to become complex. The Lux meter is a good product especially being free, but the controls are too clumsy to use and I prefer the old style wheel of the free version of myLightMeter.