reflectivity paradox

[harmonicminor]

ok heres something to think about
take a hand mirror and take something painted flat white and go outside in the sun and see if the flat white thing reflects more light than the mirror
I havent tried it yet but im willing to bet the mirror reflects more light and can reflect it much farther. the reason you can see yourself in a mirror in the first place is because it reflects light so well. I can garantee if you compare your reflection with a mirror vs. mylar that you can see yourself much better in a mirror. if a mirror sucked in so much light you wouldnt be able to see yourself in it. kinda like a black hole that sucks in light. you just wont be able to see it because it sucks in all light.
maybe I will try some side by side experiments.
plus another thing I noticed is that with mylar is that it reflects hot spots where the flat white wont so that to me kinda makes mylar like a cross between aluminum foil and a mirror.

[stickygreenlightsabr]

Where's the paradox? The mirror WILL reflect more light

[HARDDON]

No the mirror WILL NOT reflect 'more light'.

It will reflect more focused and less diffussed light.

That is what the atmosphere we have does for us, otherwise, we would all be burned up fuckers smoldering and smelling of cooking flesh all the time.

The mirror reflection is too focused for growing plants. Reflecting light from a mirror is beamed right back at the same angle or degree of pattern, thus only a small focal point is reflected.

A mylar or white background will indeed reflect the same light over a much broader, more diffused area. Better for plants.

When filming video or photography, no one uses mirrors for light...too focused and too many shadows...if the surface isn;t hit with the main refelction beam, it gets NO light...again, like the astronauts in space....

The gloves they wear.....on the side facing the sun.....the temps will reach 280 F...while the same glove, on the other side in the shadows, will reach temps of -280 F.

Mylar and white act as broad spectrum diffusers, thus in reality giving off far more light over a much shorter distance.

HAPPY LIGHTING:)

[harmonicminor]

yes you are right hardon but......... I have read many places online about mirrors sucking in light and therefore they are wrong. they should be corrected lol.
I have rubeed on mylar with rough hands and made little scratches all over it to diffuse the light better and that seemed to work ok.
hey how about a convex mirror?

[HARDDON]

Sorry harmonic....

mirrors of any and all sorts simply do not work well for diffusing light.

As for the convex, that would work great if your were the Hubble Telescope. But not for weed.

Even some of the popular parabolic reflectors being sold with light kits are trash.

Go to Wal Mart and buy some of that thick white poster board.

It will work wonders in place of mirrors.

HAPPY POSTER BOARD SHOPPING :)

[stickygreenlightsabr]

Yes, the mirror WILL reflect more light. I'm not talking about diffused or focused, just LIGHT as in photons. Re-read the original post. If that wasn't the case, then telescopes would use something else.

Also, telescope mirrors are concave, not convex.

[HARDDON]

Yes, the mirror WILL reflect more light. I'm not talking about diffused or focused, just LIGHT as in photons. Re-read the original post. If that wasn't the case, then telescopes would use something else.

Also, telescope mirrors are concave, not convex.

I re-read the original post and the post as inquiring about using mirrors for growing plants versus mylar or white color.

As I said, a mirror will reflect More Light but in a direct and undiffused manner.

This wont work for enhancing plant growth.

End of story.

[Beeblebrox.420]

Yes, the mirror WILL reflect more light. I'm not talking about diffused or focused, just LIGHT as in photons. Re-read the original post. If that wasn't the case, then telescopes would use something else.
Incorrect; at best, incomplete. A typically second-surface (silvered on the back of the glass) wall mirror has a reflectivity of approximately 85-90%, at maximum, because the glass absorbs a significant fraction of the incident light before it ever reaches the reflective surface, and absorbs the same fraction again on its way back out. Some high-quality white papers have reflectivities on the order of 90-95%. Telescopes and other precision optics use first-surface mirrors, to attain reflectivities greater than 98%.

[stickygreenlightsabr]

A-ha, I totally forgot to add that high-refletivity mirrors have special coatings. I stand corrected, but never said anything about using mirrors for growing.

[harmonicminor]

ok yes telescopes use concave mirrors a convex mirror would diffuse the light would it not?
if a mirror reflects light that isnt diffused how do you think it comes out of the light? we dont use light diffusers between the plants and the lights do we???

[Beeblebrox.420]

Some reflector telescopes have one or more convex secondary mirrors, most notably the Cassegrain and Schmidt camera types, but all have a concave primary mirror. Concave mirrors cause the reflected light to converge to a common focal point, while convex mirrors cause the rays to diverge, or spread apart. Don't confuse diverging with diffusing, however. Both types of mirror create specular reflections - which is a fancy term meaning you can see images in the reflections. Diffuse reflectors, such as paper, do not produce images.

[harmonicminor]

yup you know your shit beeble
yeah I would love to build one of those telescope with at least a 10 inch primary mirror.
what I noticed in my growroom is that before I put in mylar the white walls seemed to brighten up the whole room better than the mylar does.

[Beeblebrox.420]

yeah I would love to build one of those telescope with at least a 10 inch primary mirror.
Lemme know. I've got all the design formulae you'd need and a bunch of resources for telescope-making supplies and equipment. I can sure help you put together a nice large-aperture Dobsonian or something, probably for under $500.

[harmonicminor]

cool bro email me at [email protected]

[Zandor]

I have rubeed on mylar with rough hands and made little scratches all over it to diffuse the light better and that seemed to work ok.
hey how about a convex mirror?
Wow..you wrecked your Mylar dude. Study light refraction it will help you understand a little better what you are trying to do. Mirrors may reflect light the best. But for growing the problems mirrors have are heat spots and second and 3 order harmonics of the light spectrum to add to the adverse affect of the heat spots.

Mylar on the other hand gives the reflective properties a good partner. No hot spots and 98% lumens reflection.

[harmonicminor]

but theres one thing
when the mylar isnt perfectly flat I seemed to notice hot spots whereas a mirror wont do that. I know you are probably right though. and I have plenty of mylar so I'm not worried about ruining it. what happened actually is I sprayed some takedown spray for pests and some got on my mylar and dulled it so while wiping it off I created scratches on it. It shined it right up though and brought back some effectiveness. Heres another Idea for you what about if you used two mirrors for a reflector up by your light? the reflection of the light bulb might be as bright as the bulb itself therefore increasing the effectiveness almost 3x. I have seen on a science website where they increased effectiveness of solar cells by 3x by having mirrors reflect light from the sides and into the solar cell. being the mirror is flat I would think it wouldnt create any hot spots hotter than the bulb itself whereas the standard reflectors are bent and compress the light therefore creating hot spots.

[harmonicminor]

and one more thing
Im not even using mylar at the moment white walls on two sides and a tarp thats silver on the inside and brown outside making the other two walls. I am running a 1000w hps with a hortilux bulb and a 4 bulb teklight and two 2 bulb 2x overdriven t8 4' shoplights in a space about 8'x10'. the plants are more towards the center also and recieving plenty of light.

[Zandor]

Well ok then...why do you try a grow with mirrors and see how it goes. Trial and ERROR is the best teacher. Just put a smoke alarm and fire extinguisher near your room I think you may need it....lol

[harmonicminor]

I have another idea
build a box that works kinda like a huge periscope with 1 mirror and can shine just the reflected light down at the plants. it could take adventage of all the lumens at just one spot. maybe just use it for flourescent lights.
another idea would be a spinoff of the reflector idea make it so the light reflects down from the sides at a farther distance so you wouldnt need a light mover
possibly try with mylar reflectors as well and do side by side comparisons

the reflector in my teklight is more like a curved mirror than mylar

I could be totally wrong about this but who knows
without experimentation we will never find out

[HARDDON]

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