How did you determine how much is too much? I don’t get any bleaching in my leaves until about 8-10”
A healthy plant stretches most of its top & middle leaves upwards, even before lights-on. Once its fully saturated in photosynthates or overloaded with light then it'll display some of the known symptomes such as heat stress (excessive light transforms to heat via "non-photochemical quenching") or leaves just hang around/ down... Over time, these leaves then display other symptomse such as excessive discoloration - and hitherto become dysfunctional.
Leaves cannot do photosynthesis forever, chloroplasts differenciate themselves to become gerontoplasts (=old chloroplasts, which do not much...) and the more you overload these leaves the swifter this change happens.
So from this point of view, it's good to selectively prune older fanleaves and expose budsites and sugarleaves to DIRECT light. Esp. from the point onward when the stretch is done and buds begin to form in length & width.
Penetrating power? Explain this. If light hits a leaf, it does not pass through.
Some light does pass, some is deflected, most is absorbed, and is either used for a biochemical reaction, stored until the chemical process can happen again, or simply send away by just another lightwave.
But most importantly, different wavebands are absorbed by different subtypes of chlorophylls (and other accessory pigments) and do enter this process at another place/ pigment, thus different wavelengths have different "penetration power" or effects on what is happening inside a leaf (strictly speaking now on photosynthesis not on photomorphogenesis).
A HPS has a much better penetration power than a lm301b 3500k diode. That why Samsung made the lm301h-ONE.
Outside even the blue sky does deliver photons to a plant from all possible directions - because alot of sunlight simply gets scattered away.
Now inside a closed & highly reflective environment (such as a tent) this scattered radiation (mostly green & FR) forms an ambient light which reaches much further down, although it won't be as strong as the direct light ofc, and even more so if green & FR has been mostly excluded from the mainlight....
Then, there is also the problem of overloading certain structures if one simply throws the same lightwaves at leaves....
The law of inverse squares mathematically explains why we get lesser light readings as we get farther from a single point of light emission.
Correctly this law only applies if all stray light is
lost (such as an open environment), it does not take reflection or ambient light into account. Your lamp puts out a dedicated number of photons and this number is the same no matter how far your lamp is away.
However, there IS some loss, from reflection, from the atoms in the air (this mostly affects UV). Although this may become even a HUGE loss in an open environment, such as open vertical restaurant farms...
