questions about apogee quantum sensors/meters

ive decided the next toy i wanna get to continue tuning/building grow lights is an apogee quantum meter/sensor and have begun shopping. I have a few questions i need answered. i tried searching but couldnt find the info i needed.

first of all, ive been looking at these


so, first question, do i need the handheld meter or should i save money and just use it plugged into my computer? thats how it works right, im not missing anything? ive got a windows 10 laptop should be no problem

if so, comparing the sq420 and the sq520, i got confused about these charts


So it seems like the 500 sensor is obviously way better hence the price. and if you use the 420 sensor with warm white flourescent LED (is that what im using? Qb96s) your results will be 10.9% low? am i reading that correctly?

So when you guys use your quantum meters are you adjusting for this?

Thanks in advance for any info!

@Barristan Whitebeard @Rocket Soul hope you dont mind i tagged u guys i know u know ur shit. but idk whose got experience with this. anyone else please chime in too!

It says both sensors can be connected directly to your computer without the use of a meter and yes you're right the spectral errors in the chart are used as a correction factor for the different light sources and you can use the included software to calculate this for you, here's a video that explains it

Orb said:

It says both sensors can be connected directly to your computer without the use of a meter and yes you're right the spectral errors in the chart are used as a correction factor for the different light sources and you can use the included software to calculate this for you, here's a video that explains it

Click to expand...

perfect. thanks very much! that video was very helpful.

for our purposes, using spectrums boosted with a lot of 660nm and even 730nm and beyond it seems using the original sensor and adjusting with the tool is hardly scientific. i'll definitely opt for the full spectrum sensor.

The price difference is due to the sensors spectral response range so would really depend what different light sources you're testing and how accurate you need it to be

Original SQ420 - 410-655nm
Full Spectrum SQ520 - 389-692nm
Extended PFD SQ620 - 340-1040nm

The SQ620 should only be used with leds

damn. i didnt even see that one. that is pretty cool. my light does incorporate far red and UVB.

I guess i wouldn't getting true PPFD values though. very interesting i have more research to do. thanks!

pulpoinspace said:

SQ-626: 340-1040 nm USB output ePFD Sensor

The SQ-626 smart extended range PFD sensor can be connected directly to a computer to take spot measurements or graph and log real-time PFD using the included software.

www.apogeeinstruments.com

damn. i didnt even see that one. that is pretty cool. my light does incorporate far red and UVB.

I guess i wouldn't getting true PPFD values though. very interesting i have more research to do. thanks!

Click to expand...

Yes very cool, for near uv to almost far red the 520 would be a great tool to have, for uv beyond far red the 620, both would allow you to even out the light spread just the 620 would sense all the photons

pulpoinspace said:

ive decided the next toy i wanna get to continue tuning/building grow lights is an apogee quantum meter/sensor and have begun shopping. I have a few questions i need answered. i tried searching but couldnt find the info i needed.

first of all, ive been looking at these

SQ-420 Smart Original Quantum Sensor | USB Output

The SQ-420 smart quantum sensor can be connected directly to a computer to take spot measurements or graph and log real-time PPFD using the included software.

www.apogeeinstruments.com

SQ-520: Full-Spectrum Smart Quantum Sensor (USB)

The SQ-520 smart full-spectrum quantum sensor can be connected directly to a computer to take spot measurements or graph and log real-time PPFD using the included software.

www.apogeeinstruments.com

MQ-200 Original Quantum Separate Sensor with Handheld Meter

Apogee Instruments manufactures instrumentation to measure radiation and temperature for plant growth and more.

www.apogeeinstruments.com

so, first question, do i need the handheld meter or should i save money and just use it plugged into my computer? thats how it works right, im not missing anything? ive got a windows 10 laptop should be no problem

if so, comparing the sq420 and the sq520, i got confused about these charts
View attachment 4596390View attachment 4596392

So it seems like the 500 sensor is obviously way better hence the price. and if you use the 420 sensor with warm white flourescent LED (is that what im using? Qb96s) your results will be 10.9% low? am i reading that correctly?

So when you guys use your quantum meters are you adjusting for this?

Thanks in advance for any info!

@Barristan Whitebeard @Rocket Soul hope you dont mind i tagged u guys i know u know ur shit. but idk whose got experience with this. anyone else please chime in too!

Click to expand...

500 series are for led light sources. Some have a built in logging function.

Those can simply be used with a 5v usb type supply. Apply power and cover area as evenly and smoothly as possible. Remove power and return to computer, using apogees program to download data. For some, having a hand-held meter, and recording from that is fun. Not so much if you are planning on doing a lot of mapping.

If you see yourself using supplementary far red and uv anytime in the future, then looking at product in the apogee 600 series would be the best option for you.


Traditionally the market for these sensors was small, and there is an element of construction and calibration that reflects in the price. Universities and labs were the usual customers. An internet search will bring up canadian forestry document on construction of equivalent par sensors, with interesting detail on cosine correction "lens" for a par sensor. Again, internet research will bring up more modern replacement components to use in a par sensor. A widely mentioned one is the VTB8440/8441 photodiodes. Seen a few student papers mentioning those.