HushBlur LightMeter User Guide

Learn how to get the most out of your HushBlur LightMeter with our comprehensive guide.

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Get Started View Features

Table of Contents

Getting Started Features Calibration
Troubleshooting FAQ Support

Getting Started

Welcome to HushBlur LightMeter. Calibration is NECESSARY to ensure accuracy!

1

Download and Install

Download HushBlur LightMeter from the Google Play Store and install it on your Android device.

2

Grant Permissions

When you first open the app, you'll be asked to grant necessary permissions.

  • Camera: To access to camera for calculating metering data
  • Light Sensor: To optimize processing based on ambient light
3

Explore the Interface

Familiarize yourself with the main screen:

  • Camera mode for using front or back camera to meter, calibration required.
  • Sensor mode for using ambient light sensor, no calibration is required. Majority of android phones are equipped with this sensor
  • Calibration mode to calibrate algorithm to work on your specific android hardware(camera)

Features

HushBlur LightMeter offers powerful metering capability that work completely on your device. Take advantage of latest digital photography advancement in your analog experience.

Real time metering

Use built in camera with real-time viewfinder for smart metering in any lighting condition.

Modern UI

Modern UI combine traditional electronic meter interface with android system optimizations.

Manual Calibration

Fine-tune your calibration under different lighting conditions to bridge your android device to your analog camera.

Exposure Notes

You can save exposure notes while metering. Review the notes to improve your skills.

Not All UI Changes Reflected in This Tutorial

As we are constantly improving this app, some minor UI changes is not reflected in the screen recordings in this tutorial. In version 1.5.0, we replaced the settings button by the note button in the lower right corner. The settings can now be opened by swiping right!

Calibration: Essential for Accuracy

Calibration when another functional light meter is available

1

Gether Material

You may use another (ideally film) camera with a functional light meter or a stand-alone light meter. You may borrow it as it won't be needed after calibration is done.

Print out the calibration board on a white paper, US letter or A4 would work.

Pro Tip

Try to fit the paper with the whole image, leaving minimum white edges.

2

Go to Calibration Mode

Start the app, click the calibration mode button. You will see a screen with a plot

Switch to manual input mode when needed. You will be able to manually type the aperture and shutter speed

3

Sample Data Points

A. After setting the ISO to 100, point your film camera with a functional light meter at the calibration board. Try to fill your viewfinder with the calibration board without showing too much white space on the edge. Take the readout: the aperture and shutter speed

B. Type the aperture and shutter speed readout into your app.

C. While framing the calibration board in your app in the same way you frame your (camera) light meter. Click the ADD button. You will notice a pink dot appears inside the blue circle, representing your latest data point.

D. Repeat step A to C under different lighting conditions, until you have at least 6 data points(pink dots) in a (almost) linear fashion. You may remove wrong data points, or clear all data points with the Remove and Clear button.

The calibration board is updated and the screenshot is showing the older version of the calibration board

4

Calculate and Take Note of the Result

After acquiring enough data points. You may click the Calculation button. The line will move. It should go from the top left to lower right, but not perfectly diagonal.

Click the plot. A dialog will pop up and you can take a screenshot of the dialog and manually note down the numbers in the dialog. Save it for later. In case of reinstalling the app, it will be needed.

Remember to save the calibration parameters!

5

Activate the Calibration

Now you have the calibration parameters saved. By clicking the gear icon, you can open up advanced setting and check the linear calibration button. In camera mode, you would notice a pink "*" beside your EV100 measurement when the linear calibration is turned on.

Calibration when another functional light meter is not available, but your device has a light sensor

This function is experimental. So far we found it not as good as the method above.

While most phone does have light sensor, some android device is not equipped with it, therefore you won't be able to use this function on those devices.

1

Switch to the Correct Camera

Select the camera facing the same direction as the light sensor.

2

Data Sampling and Calculation

If the interface still shows the input box of A and S for aperture and shutter speed, click it. In the popped up dialog choose Light sensor(automatically read in by the app)

Follow the same steps, except when input the readout from the another physical device, use the readout from your light sensor. The light sensor readout from your light sensor will automatically update. Just make sure you frame the calibration board correctly.

Metering

Camera Mode: Average or Spot Weighted

Use the camera as a viewfinder and metering source

  • Be sure to turn on the linear calibration after you have completed the calibration steps
  • Select a mode: you have aperture/shutter priority and manual mode
  • Adjust setting as you are using a modern camera. Set the ISO, exposure compensation, shutter speed and/or aperture by sliding the wheel.
  • Using the preview window to frame the scene you want to take a picture. Read out the metering value. In aperture priority, you would want to read the shutter speed. In manual mode, you would read out the exposure compensation value.
  • The default metering mode is average metering. By tapping on the preview window, you can select a metering spot to activate spot weighted metering mode. Double tap will switch back to average metering.
    • Spot weighted metering on high contrast scene
    Spot weighted metering on low contrast scene

Exposure Tip for High Contrast Scene

We found some of the android devices we tested are more or less "highlight weighted" in its default average metering mode. Those android devices will make exposure decisions based on the highlight of the scene. This means for the scene of high contrast (even when the highlight is a very small part of the scene), the app will give you exposure that might underexposure the overall scene significantly. For instance, a typical landscape scene with trees/grass in the foreground, bright cloud in the background. This behavior won't go away with our calibration function. User might need to add 1-2 stops of exposure in these cases to correctly exposure the film. Another way is to meter multiple times by framing that include/exclude the highlight, then make a 'mental average'.

As of the version 1.7.0. Spot weighted metering is introduced. The "weighted" means the same as in "center weighted metering". It applies a great weight on the spot you clicked but still consider the rest of the image. You may use this function to evaluate the highlights, the midtones and the shadows individually. And determine the correct exposure based on the measurements. You can also use the spot weighted metering function to understand the metering logic of your specific device. We found the devices we have are indeed heavily highlights weighted by default.

Light Sensor Mode

Use the ambient light sensor of your device as metering source

  • Portrait: You would directly place your phone near subject, pointing the sensor away from the subject, towards the camera location, and readout the metering result. Sample at different location at subject's face as you are using a traditional hand-held incident light meter with a flat diffusor.

Exposure Notes

New Feature. Unstable

Exposure note is a newly(2026/02/20) introduced feature in version 1.5.0. It stores all notes on your device.(Will be deleted after uninstalling) While we have tested it and ensure the basic functions are working as expected, the changes are quite extensive. So it may not be stable. On the other hand, related features are subject to change as we get more feedbacks. In the extreme case, exposure note data might be lost. Therefore, in version 1.6.0, we added a note exporting function to ensure users have the ability to export their notes, as a mean of data backup.

Saving Notes

  • Click the note button in the lower right corner on the screen while in camera or sensor mode will open the note saving dialog. Enter details, or leave them as is and click save. Exposure lock will be on when the dialog is open so you will be capturing the metering information when you click the note button.

Viewing and Editing Notes

  • On the home screen, clicking the exposure note will open the note editing dialog. Click any note to edit or delete. Each note is displayed in the following format:

Exporting Notes

Export exposure notes to a file in "comma-separated values" format.

  • In the settings drawer, click "Export Exposure Note". The notes will be saved directly at Documents folder in your android device as a .txt file.
  • For older android devices, clicking the "Export Export Note" will create an internal .csv file(user have no direct access to), made accessible only to another program of your choice. You can choose to use your browser to save(or "download") to a user accessible location, for instance, the Download folder.

    • Troubleshooting

    Solutions for common issues you might encounter.

    App Crashes or Freezes

    • You will need your saved calibration parameters after re-installing the app.
    • Ensure you have the latest version from Google Play Store
    • Close other apps running in the background
    • Restart your device
    • Clear app cache in Android Settings > Apps > HushBlur LightMeter > Storage > Clear Cache
    • Manually input your calibration parameters.

    Frequently Asked Questions

    Is the calibration step necessary?

    Yes, it's necessary. Hardware and lower level camera interface implementation differs from one manufacturer to another. Without calibration, the readout from camera feed can be off by a lot!

    Is the calibration for camera mode only?

    Yes, it's only going to affect camera mode readout. Ambient light readout, used in sensor mode is not affected.

    Does HushBlur LightMeter require an internet connection?

    No, all image processing happens locally on your device, then discarded. An internet connection is only required for downloading the app and future updates.

    Are my photos stored on any servers?

    No, all processing is done locally and no images are uploaded to any server.

    Can I use HushBlur LightMeter on multiple devices?

    Yes, you can install HushBlur LightMeter on multiple Android devices using the same Google account. Each installation works independently.

    Why do I see an exclamation mark beside my camera choice in the settings/side panel?

    Some camera might not fully support the feature we requires, so we add this to alert the users. Sometimes, on older device, the lower level software is not compatible with this app.

    Need More Help?

    Our support team is here to assist you with any questions or issues.

    Support

    Contact us directly at the following email for personalized assistance:contact@example.com

    Community Forum

    You may also view/discuss related topics and ask questions here!

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