The smartphone as a light meter
Film cameras are all the rage. But they often lack a light meter, or their cell fails. The solution? A smartphone application for measuring light. With a few precautions, it can effectively replace a light meter.
Hasselblad, Leica, and Rolleiflex are the brands for lovers of 35mm or 6×6 film cameras. You’ll be looking for a Linhof Technika or an Arca Swiss in large format. These cameras often lack a light meter. A digital camera equipped with a reliable meter, can calculate exposure settings. But this is a cumbersome solution that lacks spontaneity. An independent light meter from Gossen, Kenko (which has taken over the Minolta range), or Sekonic guarantees reliable measurement without weighing down the camera bag.
Smartphone applications
Today, we all own smartphones. So, any owner of a model running iOS or Android can download, free of charge or for a few euros, an application that turns their phone into a light meter. The dedicated application calculates exposure according to measured light thanks to the built-in camera. However, the accuracy of the measurement requires a few preliminary checks to avoid unpleasant surprises.
Among the available apps, we looked at myLightMeter Pro, as its developer, David Quiles, has declined it for iOS and Android (under the name LightMeter). The app works in both reflected and incident light.
We compared it to the measurements of a Minolta Flash Meter VI flashmeter (whose most recent equivalents are the Kenko KFM 2100 or 2200) and a Nikon D850 camera. The Minolta light meter is twenty years old, but its measurements are as reliable as Sekonic’s flagship L-858D.
Calibration
Reflected light measurement is the easiest to perform, requiring no accessories. Simply point your smartphone at the subject as if taking a standard photo. The application displays the measured field. Depending on the device used, you may be unable to zoom into the field. Zooming is impossible on an iPhone SE, unlike on an Oppo Reno8 Pro. However, on the former, the Classic interface can be switched to Pro, and a precise field area can be selected for measurement. Whether the field is broad or narrow, the measurement is average.
With the iPhone SE, measurements taken on plain white or grey surfaces underexpose by ⅔ of an EV compared to those recorded with the Minolta light meter or with the Nikon D850 in spot metering mode. With the Oppo Reno8 Pro, they overexpose by 2 EVs. The app allows you to compensate for these discrepancies ranging from -1 to +1 EV for the iOS version and -5 to +5 EVs for the Android. It is, therefore, essential to compare smartphone measurements with independent light meter measurements.
Incident light measurement
Incident light measurement is an essential function of independent light meters. A diffusion dome is placed in front of the light-sensitive cell of the light meter. The light meter is placed close to the subject, with the dome pointing towards the camera. It thus measures illumination at the subject level. For a smartphone, no dome has been designed by phone manufacturers. A few app designers like Lightray offer one, but it’s designed for an application simulating a luxmeter, not a light meter for photography. Luxi is no longer producing its own. The Lumu Power 2 from Slovenia’s Lumu is only available with an Apple Lightning connection. myLightmeter Pro suggests cutting a translucent box of 135 film cartridges and inserting it into the phone.
Therefore, a comparison measurement with an independent light meter in incident mode is essential to assess the correction required. However, this correction varies according to the position of the film canister on the smartphone lens. In the absence of a dome, it’s worth remembering that a measurement taken on an 18% gray card evenly lit gives the same value as a measurement in incident light. In any case, nothing beats an accurate light meter in incident light. And to return to film cameras without a cell, let’s not forget that the cost of film and development and the time spent waiting for the result are worth the investment in a more reliable metering accessory than a telephone, even a smart one.
Discover the photography courses at Spéos
Spéos offers various training courses ranging from simple one-week photography workshops (initiation and advanced level) to 3-year courses. The long courses to become professional photographers allow you not only to master all the photographic techniques and its vocabulary (blurs, hyperfocus, sharpness zone, depth of field, backlighting, focal length, shutter release, autofocus, wide-angle, rule of thirds, etc.), but also all the stages of shooting and image processing.
Visiting the school allows you to discover the premises, the studios and the equipment, and is undoubtedly the best way to familiarize yourself with your future way of working. This is why, in addition to the open days, Spéos offers throughout the year personalized visits by appointment to come and discover the school with a member of the team.
Text and photos: Philippe Bachelier, teacher of Printing techniques at Spéos
