Light intensity reading

I've been meaning to get around to this for some time however I am still confused over what type of meter is most accurate (cobs/cmh) and what type of price range is required for a useful reading, doesn't have to be 100% accurate. I've seen some use a phone app but I never trust anything smart phone, could I be getting old?.

Any help appreciated.

Best measurements for light is par/ lux/ PPFD, any phone ones will be mostly lux and they’re free but the meters are all of them and beyond but also cost 200+ bucks for a decent one

Any ideas on specific brands?. I am ok with around a 15% error reading.

Have you watched the YouTube phone meter and quantum comparisons?

Flowki said:

Any ideas on specific brands?. I am ok with around a 15% error reading.

Click to expand...

I use this one and it gets it done. Divide by 67-69 depending on your COBs kelvin temperature. Not sure about the CMH as I use COBs and QBs, probably close enough. I really like this meter for helping me position my lights depending on the plant's life stage.

Tetrahedral said:

Have you watched the YouTube phone meter and quantum comparisons?

Click to expand...

I seen the one after this post by an Irish lad using a $30 meter and a 0.028 or so conversion rate from the expensive meter, that's the one?.

buyyouabeer said:

I use this one and it gets it done. Divide by 67-69 depending on your COBs kelvin temperature. Not sure about the CMH as I use COBs and QBs, probably close enough. I really like this meter for helping me position my lights depending on the plant's life stage.

Amazon.com

Click to expand...

This seems to tie in to the above. Tell me though, how are you to know what kelvin temp the cobs are? (does the driver say this?). I know that I have some that lean into the blue and some that lean into the red. Would you expect the units that lean into the blue would have a lower or higher reading?. they were pre made and I've had them a good few year so I forget the exact kelvin ratings.

I have 6 units that all have two led chips each. The units are 200W each. I wonder how would the light reader do in this overlap situation of differing spectrums?. Could I get the high/low values and then split in-between as the end value?.

All I am really wanting to do is get a feel for the par per square foot figures so I know for sure how low/high the lights should be within a few inches. I am trying to dial in ppm/rh values and thinking that my ''intuition'' is not good enough to do it by sight.

Most COBs are going to be in the 3000k to 3500k for general veg/flower use (it has nothing to do with the driver BTW). The divide by 67-69 is an estimate for conversion; so close enough in most cases if you are just measuring for intensity / distance. If you really want to know their color temperature you can perhaps check online if not and they are white full spectrum just use 67. I don't even worry about converting anymore; 15k lumens for seedlings, ~30k for veg growth and ~50k for flower.

Here is a thread with some more info and numbers, showing you can use multipliers too.