Light measurements for terrarium

[Tonio]

not to hijack your thread but:

Photone is a more then decent app for measuring light levels in PAR/ppfd, lux etc. On Iphone's it uses a simple paper diffuser and is usually less then a few % off compared to expensive PAR sensors. For android there is a Beta version out that has no need for a diffuser I don't know if it is equally reliable, but it should be better then other apps anyway. (it uses the front camera instead of the ambient light sensor. needles to say the camera is a way superior light sensor)

The problem with lux and food candles is that is based on the human eye. Which is most sensitive for light around 550nm (at daylight, at night with low light levels our eyes are most sensitive for 500 nm, that is why we feel moonlight is a cooler light source as sunlight, although it is warmer expressed in Kelvin)

Plants however can use all the light between roughly 400 and 700 nm. PAR (photosynthetic active radiation) expressed in ppfd (photosynthetic photon flux density) measures all those wavelengths equally instead of favoring one.

Lamps with higher Lumen/Lux can actually have lower PAR ratings then lamps with lower output in lumen/lux. This means that it could provide less or more light to the plants then you would think based on lux levels.

a second aspect is that intensity does not matter that much: a plant needs (and can handle) a certain amount of photons (light particles) per day. A shorter period with higher intensity or longer period with lower intensity can both provide that. DLI (Daily Light Integral) expressed moles per meter per day, is therefor the best way to compare lightning conditions.

The Photone app calculates DLI for you, assuming lighting conditions are stable during the day. In a terrarium this is usually the case since artificial lights are the main light source.

I have no interest in this app what so ever, but it is a free way (if you have a smartphone) to get reliable and comparable data that could be really useful for a lot of hobbyists. So felt the need to mention it...

[camille1585]

Originally Posted by Tonio

not to hijack your thread but:

Photone is a more then decent app for measuring light levels in PAR/ppfd, lux etc. On Iphone's it uses a simple paper diffuser and is usually less then a few % off compared to expensive PAR sensors. For android there is a Beta version out that has no need for a diffuser I don't know if it is equally reliable, but it should be better then other apps anyway. (it uses the front camera instead of the ambient light sensor. needles to say the camera is a way superior light sensor)

I have Photone on my work iphone, and just installed it on my android (had no idea that there was a beta version out!).

I have been very curious about the accuracy of the app, but the cost to unlock the LED measurements is a bit much, and there is no trial version... I also have an old iphone 6, so wonder if it is as accurate as newer models. I work in R&D at an indoor farming company and do a lot of trials with light and would be able to compare the PAR measurements of the app with those of high end quantum spectrometers.

I did test the android version just now with the B+R LED setting, and it is way, way, way off. I know that it is in beta, but I'm getting readings of max 120 μmol/m2/s at 40cm from the LEDs, while I know that the lamps were calibrated at 290 μmol/m2/s at that distance, at the start of the experiment. I will try to calibrate my phone next time a room is measured.

While I agree that it is better to measure light in terms of PAR, for the average hobbyist I think that lux and footcandles are much easier to handle, and good light quality meters can be had rather cheaply. There is also a lot of data out there on lux/fc values for various types of orchids. If the person buys decent quality fixtures with spectrums which are already geared towards plant growth (so not a generalist shop light type fixture), lux/fc measurments should be good enough.

PS: Did you notice that the app changed names during the pandemic? It used to be called Corona, like the solar corona.....

[SADE2020]

Originally Posted by camille1585

While I agree that it is better to measure light in terms of PAR, for the average hobbyist I think that lux and footcandles are much easier to handle, and good light quality meters can be had rather cheaply. There is also a lot of data out there on lux/fc values for various types of orchids. If the person buys decent quality fixtures with spectrums which are already geared towards plant growth (so not a generalist shop light type fixture), lux/fc measurments should be good enough.

.

Mainly because is easier I ask specifically about FC and Lux. Just average could give me an idea of what others are controlling.

Thanks all ...I still need some info got the actual question

[Tonio]

Originally Posted by SADE2020

Mainly because is easier I ask specifically about FC and Lux. Just average could give me an idea of what others are controlling.

Thanks all ...I still need some info got the actual question

I have no personal experience with those species. But according to my data masdevallia in general would do fine between 8500 - 16000 lux, (800 - 1500 footcandles) natural light for 12 hours a day. Sources differ a bit. In general plants can deal with higher light if kept cool and humid.