Useless Subjective. Tells you to tape "white paper to phone" – MQ GreenThumb Review

The readings on this meter are completely inconsistent the reason for that is because of the diffuser apparatus that they have you construct out of paper and tape this apparatus is no special instructions on what type of paper to use so the thickness and weight of the paper you use drastically alter is the footcandle reading. This is not a accurate means of discovering the light levels in your growing space
Review by Hauwis2 on MQ GreenThumb.