Simply move the dials at the bottom of the screen to line up the desired aperture and film speed you have loaded and press the "Meter and Lock EV" button. Once this has been pressed, it will lock the scene Exposure Value (EV) internally and calculate exposures based on that number. After you have locked in, the three wheels at the bottom will work in Aperture Priority mode. Changing the aperture (f-number) or ISO will automatically change the shutter speed to the correct exposure.

If you want to shoot at a certain shutter speed, you can change either the aperture or the ISO until you reach your desired shutter speed.

Tap on the top right corner on the roll of film to access the film menu. Once there, you can select to create a new roll of film. Run through the wizard and it will be set up for you.

Once you have a roll of film open, you will see the file name at the top of the app. You will also notice right below the film menu there is a list of numbers with a red button at the bottom of it. The numbers represent which frame you're on, and the red button records your settings into your film log. Once a frame has been recorded (shot in camera), the frame will then be marked with an "X" in front of it.

Tap on the film menu, and tap on "Manage Film". Once there, you can share, rename, or delete the film log. If you have Dropbox install, you may share it to your Dropbox folder.

You may open, save and close different film files before closing them. This way you can keep track of multiple rolls of film at a time. Tiny Light Meter makes film roll management very easy.