Return to the Growing under Lights Forum | Post a Follow-Up

Understanding Light Intensity through Light Meter

Posted by saood Saudi - 10b (My Page) on
Sun, Oct 27, 13 at 3:27

I download an android light meter application, that had good reviews from its users. My intention was to measure the intensity of sunlight during the day. From my discussion with "Art33", a GW member, whom I am greatly thankful to, could make out that the indoor readings under floru lights from my application and his "Dr. Meter" light meter were sort of giving similar readings. While not a pure scientific confirmation, it did help me in assessing the accuracy of the application.

The application works by receiving light rays into the small light sensor that is just besides the front camera of most android based cell phones. Now when I tilt the phone to face the sun, it always gives me maximum reading except for very early morning (i.e. within 30 minutes of sunrise. After which it reaches max reading of 12000 foot candles). However, as I move the tilt of the phone away from the sun and towards the sky, the reading keeps on reducing. These reading made me curious about light intensity. Now, unless you conclude that the application has any programming / other issues, I would assume that since the light sensor is very small, it can only provide the correct reading when it is facing the source of light and that is the correct reading when light intensity is being measured (especially when sun is the source of light)? Is it so?

Follow-Up Postings:

RE: Understanding Light Intensity through Light Meter

Useless in my opinion.
The only thing that comes close to being useful under $500 is the SQ-120: Electric Calibration Quantum Sensor from Apogee

I bought several light sensors and just gave up on their reliability and made my own calculations based on educated studies rather than useless measurements.

Read this pdf from Purdue

and this pdf from Cornell

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Growing under Lights Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here