Light meter · iOSMeterGlass
An iPhone light meter for film photographers.
Averaging metering, spot metering and Zone System analysis on your phone — built for large format and film photography.
By the studio · iOS
What it is
MeterGlass solves a very practical problem: when you've left the meter at home, or you just want to confirm exposure quickly on location, your phone can still give a reliable reading. It isn't a generic camera-filter app — it gathers metering, zones, format masking and filter and bellows compensation into one workflow you can act on directly, and it works together with its sibling TimerGlass (reciprocity-failure correction and exposure timing).
Core capabilities
Averaging metering with live readings
Averaging metering across the framed area, with live EV, illuminance and colour temperature, and exposure lock (AE-Lock) — a fast way to set an overall exposure baseline.
High-precision spot metering
A roughly 1.5° spot meter with pixel-level luminance analysis at 0.1 EV precision, for sampling highlights, shadows or a key lit surface on their own.
The Ansel Adams Zone System
Sample several points and place them on zones, get N+ / N− development suggestions, and generate a shareable metering record card — linking measure, judge and record into one chain.
Multi-format masking
Masking for film formats from 135 to 8×10, with the equivalent focal length shown, and metering within the mask — so composition and exposure come together for the target format.
Filter factors and bellows compensation
Filter stops, bellows extension and other compensations feed directly into the exposure suggestion, cutting on-site mental arithmetic; bellows extension can be converted to stops automatically from focal length and extension.
Calibratable and fine-tunable
Metering calibration in 0.1 EV steps to align with a grey card or a reference meter, and exposure compensation of ±2 EV on a sliding scale.
A wide range of exposure combinations
Apertures from f/1 to f/256 in full, half or third-stop steps, with 135 and 4×5 equivalent focal lengths shown — covering everything from rangefinder to large format.
A multilingual interface
Six interface languages, so film users in different regions can get started right away.
Who it's for
- Film and large format photographers who need reliable on-location metering and zone judgement
- Anyone who regularly uses filters, bellows and multi-format composition, and wants compensation folded straight into the exposure suggestion
- Users of TimerGlass, current or planned: the shutter time MeterGlass measures can be sent over in a tap, to continue with reciprocity correction and exposure timing
MeterGlass — a film metering bench on your phone: averaging, spot, zones, formats and compensation. Meter, then shoot — and hand off to TimerGlass for what comes next.
Download on the App Store