Tap Log frame on the meter after each shot to keep a record of your settings for this roll.
Add your own film
Phones process their photos, so readings can sit a little off. Meter the same evenly lit scene with this app and a meter you trust (or Sunny 16 in clear midday sun), then set the difference here.
Centre-weighted behaves most like the T3's own meter.
Tap Meter and take a photo of the scene. Your phone picks its own exposure and records the shutter speed, aperture and ISO inside the photo. The app reads those numbers, then measures how bright the scene is compared with middle grey, and turns that into an EV reading.
Afterwards you can switch pattern, or choose Spot and tap any part of the photo to meter just that area. The bar under the reading shows how far the darkest and brightest parts of the scene sit from your exposure, against what your film can hold.
Use the photo button in this app. A photo picked from your library may have had its exposure data removed.
This deletes your films, roll and shot log.