Problem metering and setting the light level.

BigBlonde · Nov 23, 2022

This is kinda weird...

I have two Android phones with the Photone app installed. The PAR meter readings are very different. The left phone in the pictures is an S22 Ultra and the right phone is a Note8.

Here are the two phones side by side in the center of the tent:

Here they are at the left side of the tent:

Here they are at the right side of the tent:

To make matters even more interesting, setting the left light to about 20% lower (30%) than the right light (50%) results in the left-side reading being higher than the right side reading. Both lights are the Viparspectra XS2000 model and are hung at the same height. All the readings were taken with the door zipped shut except for enough room to poke a camera lens through to take the pictures.

Recommendations for a better meter (at a reasonable price) are welcome, but aside from that, what the heck could be going on here?

Here are the two phones in daylight:

CookiesLikeWhoa · Nov 23, 2022

Realistically you're never going to get very accurate numbers using your phone. You can reduce the range you will see by properly setting up your phones camera, but ultimately you'll have a very wide range to work with.

Consider those ball park numbers.

Also if different parts of your tent are getting different light levels, that means the light is not centered or something is blocking the light.

BigBlonde · Nov 23, 2022

CookiesLikeWhoa said:
Realistically you're never going to get very accurate numbers using your phone. You can reduce the range you will see by properly setting up your phones camera, but ultimately you'll have a very wide range to work with.

Consider those ball park numbers.

Also if different parts of your tent are getting different light levels, that means the light is not centered or something is blocking the light.

If those are ballpark numbers, it must be a pretty big ballpark. I set a board across the pots to make sure the phones were positioned similarly. Nothing was blocking the light. Even outside in unobstructed sunlight there was a difference of 67. That doesn't inspire confidence.

I'm not sure what you mean by setting the phone's camera properly. I'll see if I can find information about it.

CookiesLikeWhoa · Nov 23, 2022

The camera can have a diffuser put in front of it to reduce glare and incorrect readings.

I usually considered the ballpark around 100PPFD on my iPhone.

I eventually got an apogee light meter and compared it to what my phone was putting out. Not even close lol. Usually my phone would be about 100 PPFD off, in either direction.

BigBlonde · Nov 23, 2022

CookiesLikeWhoa said:
The camera can have a diffuser put in front of it to reduce glare and incorrect readings.

I usually considered the ballpark around 100PPFD on my iPhone.

I eventually got an apogee light meter and compared it to what my phone was putting out. Not even close lol. Usually my phone would be about 100 PPFD off, in either direction.

The Photone website says a diffuser is needed for iPhones, but not needed for Androids. An Apogee meter is probably in my future.

Smokey0418 · Nov 23, 2022

Not weird at all.

One must calibrated there app to a said par map for example to get a closer true reading.

Or better yet , a friend with a gauge.

BigBlonde · Nov 24, 2022

Smokey0418 said:
Not weird at all.

One must calibrated there app to a said par map for example to get a closer true reading.

Or better yet , a friend with a gauge.

Thanks. I'll try to calibrate one of the phones after the holiday. The cost of the gauges too much for me.

freezeland2 · Nov 24, 2022

BigBlonde said:
Thanks. I'll try to calibrate one of the phones after the holiday. The cost of the gauges too much for me.

I wouldn’t get to hung up on the accuracy. Just pick one of the two and use that one exclusively. The ppfd number is just a point of reference. Watch the plants to know if the intensity is right. When the plants present their leaves horizontal and flat you are at their sweet spot.

Problem metering and setting the light level.

Problem metering and setting the light level.

BigBlonde

CookiesLikeWhoa

BigBlonde

CookiesLikeWhoa

BigBlonde

Smokey0418

BigBlonde

freezeland2

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