biggest diff i'd say is distance between tops and light. strips might be more efficient, idk but cobs need a heatsink.
A lot of people use heat sinks with strips but a lot don't either when they run them at or lower than <50% total power.
Theres a difference in throw. You can easily build a light with strips which is homogeneous in diode density. But that will give a hot spot in the centre due to cross lighting. Which accentuates with hanging height.
Good points.
Ots a good work around but as is will only work on one dimension, depth or width. For a perfectly square space you a bit stuck unless you make a square/frame like thing, something like this:
They have diffrent uses. Cobs especialy with good lenses will penetrate downwards and hold a higher ppfd verticly rather than spred the light width wise as much. Although you can adjust the width some by using 180° spred or 120° or 90° or 60° . But the more out wards/ width wise you spred the light the less strength downwards. So for example if you want to grow 7-8 ft tall plants and have the buds grow top to bottom good then cobs are great but you will probably need higher ceilings. They use cobs in light houses with specialist lenses wich throw out strong light deep deep into the sky ( smd spred out on flat board wouldnt be able to do that) Oh and cobs can end up costing more as they require specialist cooling sinks and lenses .
No matter what you do with cobs and lenses, 3-4 leaves deep into the cannopy there is not enough light for the light down cannopy to really be driving bud formation. Buds all the way down as a function of light is a myth imho; ive seen solid 5g nugs growing low in about 50ppfd environment. If i had the same 50 ppfd on the top id get nothing but the larfiest larf. Those buds growing big in 50ppfd is getting their energy from the top cannopy and they are more a function of pruning lowers and sucker branches, in order to not waste plant energy.
Can you put up the exact cobs you used, wat lenses they were and the meteral they were made from, aswell as the lense spread. If light houses are being fited with cobs that can beam out huge distances that says enough. Eg try puting a plant in a 5x5 x 7 tent with 600 wats of smd led chip with a big board or bars. And then do the same with a 600wat cob with the right lense on and put your plant under it. I gaurantee you the plant will be fine with 600 wats of smd on a big board or bars but try that with the 600wat cob and its going to burn the plant right the way through. Ive seen it with my own eyes. Just becase certain midrange cobs are sold to growers dont mean thats all that out ther. Iv seen cobs at like 2000 wats ect. Try putting your plant under one in a tent and tell if it survives over night.No matter what you do with cobs and lenses, 3-4 leaves deep into the cannopy there is not enough light for the light down cannopy to really be driving bud formation. Buds all the way down as a function of light is a myth imho; ive seen solid 5g nugs growing low in about 50ppfd environment. If i had the same 50 ppfd on the top id get nothing but the larfiest larf. Those buds growing big in 50ppfd is getting their energy from the top cannopy and they are more a function of pruning lowers and sucker branches, in order to not waste plant energy.
You may be right with a very deleafed grow or a strain if the cannopy is very forgiving (i cant remember the word opposite to dense) but if you got anything like a full cannopy this lense thing isnt going to make as much impact as how you prep your plant for flower.
You are completely right if you have very high hanging height; especially the cobs around the walls or perimeter of the cannopy, lenses help here in order to not lose light to the walls. Bu assuming the cobs in the middle of a large open space wont lose light majorly to walls they are better left uncovered as these will be helped by crosslighting. Light is never lost to air, if just spreads, the case for lenses is not good over a large cannopy but as you say excellent for light houses.
Penetration is one of my pet peeves, to the point i refer to it as the P-word. Nobody seems to be able to actually define it further than buds all the way down (which is covered above), and when defined as light levels in lower cannopy its never really measurable, even if employing stuff like reflectors and lenses - they can help shape the light above the cannopy but they do little inside the cannopy.
You could say that penetration is a function of spectrum though as the lower you go the more green light you find, this is one of the reasons blurple never produced well.
Ymmv
Dude, just get a ppfd meter down the cannopy of your grow with lenses and youll see what im talking about. Behind the leaf theres shadow. Doesnt matter how you shape the light before it hits the leaf, behind the leaf theres shadow.
yeah some light goes thru the leaf, thats for sure. How much? Not enough to build buds on its own. Yet there are buds right?
Yes, but even so the "penetration" as in bud formation deep into the cannopy is fairly independant of the light levels that hit the lower bud. As ive stated even in low light conditions of buds 40-50cm down; we can get nice hard bud at about 50ppfd as long as weve done the plant management well: not letting them stretch too much as this spends the plants energy and also not letting each and ever budsite flower; too many buds and you spread the plant to thin to generate the right type of bud formation. This is why the P-word peeves me; the thing that people talk about as penetration is not as light dependant as people think. If there is a light component id say its the spectrum: green penetrates deeper, both in the cannopy and in the leaf. This is why old blurples didnt give "penetration" every ounce of light gets absorbed in the top, as well as in the first layer of the thylakoid which means less photosynthesis and less buds in the lowers.
I dont think you unserstand the same shadow is still there with hid and the sun. The way around that with the sun is it huge so the daylight comes from all over multiple angles. With led the shodows are over come by using more than one point of light. Ther is always going to be some shadow no mater what but thats why there are leaves and ther in multiple places of the plant. The leaves even angle towards the nearest strongest point of light. The more light they can take up,not just afew on the top but accumilate from all over the more its going to put into the plant. One other thing your ppfd meter cant read some wave lengths good, some wavelenghts punch right through the leaves sort of like x-rays. The plant dont see like a human. And for a more better understanding of the ppfd the plant gets try messuring ppfd from every leaf on the plant at the angle it faces. Any way i dont think its a good idea to have the plants grow so close together that no air and light can pass through nothing but the top of the canopy. Also it would depend on growing style as scrog is based around making use of the width to spread rather than growing multiple bigger 5 - 7ft plants. So the grow style,and place mater to fit the right lighting solution.Dude, just get a ppfd meter down the cannopy of your grow with lenses and youll see what im talking about. Behind the leaf theres shadow. Doesnt matter how you shape the light before it hits the leaf, behind the leaf theres shadow.
If youre growing like this you could easily show me penetration thru the cannopy with a light meter. Of course, if you use a lense focusing a 600w cob onto a plants top cannopy you will fry the plant. Cause yeah, all of what youre saying about your lighthouse. Frying a plant is not penetration and doesnt mean that youll have light under the top cannopy cause its in shadow. Can you get a super strong lense on a cob and make it penetrate a mountain or a wall? Why not? Shadow, it litterally wont go thru things that are not transparent
If you fry the plant youre not penetrating, youre burning leaves so once dead theyre dead and gone, hence just air which is also... Transparent.
Check out this thread with measurements of lightlevels in top mid and lower cannopy.https://www.rollitup.org/t/far-red-light-penetrates-the-canopy-more-than-you-think.1096796/#post-17482432
1000/70/10 ppfd. I can guarantee you there was buds in mid cannopy. Fair enough its boards, now show me what you get with your lenses grow, down cannopy about 2feet.
When i say buds at 50ppfd, yes, but my top cannopy is at 1000. Depending how i managed budsites i can get buds of good size towards the bottom, where i have around 50ppfd. No shit. The plant can grow buds with low pofd intracannopy cause it already harvested the light at top cannopy.
If you seen this youre talking about then show us, im betting we will never see any photos showing 800ppfd in mid cannopy cause it seems like youre plain theorising, never actually measured this. Just saw something and felt wow. What youre talking about is focusing light which of course works. Until it hits a solid material which isnt transparent, then you get shadow. Yes a little light goes thru but your insane if you think that little light is what is growing the buds down cannopy, its all
Ill try to see if i can get pics next time im at the grow.
Edit: sorry, i may be getting abrasive on this issue apologize if im getting rough around the edges, the P-word gets me in a bad way
I dont know if were talking past eachother. My argument is that lenses will not increase penetration, just that and if you "measure" P with how many buds you get on lowers youre barking up the wrong tree.
what youre talking about is diffused lighting vrs parallel or focused lighting, yes diffused light is present both from boards and the sun, but in the case of the sun its only half of the story. Sun light is parallel above the atmosphere, as straight as can be as even though the sun is huge in its origin its so far away that once ots reaches the sun its considered both pointlike and parallel. Once it hits the atmosphere (or once somewhat obscured by cloud cover) it gets scattered: this is the part of the sunlight that "comes from all directions" as you describe. But its only part of yhe story as all sun light dont get scattered, some of that parallel light also gets thru. This light can be compared to what you describe as lensed focused lighting and definitely wont be very present going down into the cannopy.