I read some articles which say that watching movies
from projector screen is better for eyes and make less
eye strain than tv screens,since the light from the projector
is diffused from the projector screen so the eye see the reflected
image opposed to the tv screen which are a directed light.
But what about the reflective screens?
I saw that there are a grey screens with a metal coating
and bead particles(fiberglass,i think)that,in practice,focus
the light in a narrow angle rather diffuse it,in a way that
the gain can reach up to 3 in 0į.while beyond 20į+/- it
decrease to 0.5 gain.
So since those type of screens are focused and amplifying the light into a narrow angle rather than diffuse it,doesn't that make them wrose on decreasing eye strain compare to the diffuse screens?and doesn't it even wrose than watching direct light from tv screen?or it is actually
still better for eyes than a tv screen in spite of that?
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Yes, and better contrast is easier on the eyes, up to a point (a VERY HIGH point). If this were not true, HDR would not be so appealing.
Many/most direct view TVs have better contrast than many projectors (until you get into high grade theatrical or commercial or HDR quality).
Of course, much also depends on ambient light, which can screw both forms up (and maybe this is what those articles were meaning to allude to). Since there is usually a clear, glossy screen on TVs, ambient reflections can cause glare which reduces contrast. Ambient light can also mess up higher gain projection screens. In fact, with HIGH direct ambient light, sometimes rear-projection is preferable, even with its lower contrast, just because there is less direct glare. All of this can easily be avoided, however, if one follows the best practice of watching in an environment with little to no ambient light. Hence, a movie theater-style design makes good engineering sense. For TVs and projection screens alike.
Thanks for your replies.
I understand that the brightness,the contrast and the ambient light
are all related to that,but my intention was a little different.
This is the reason why i focused my description on the reflective metal coating screen.
I ask my question in other way:
If you look directly on the beam of the projector,you may damage your eyes(retina).
If the projector sends a beam of light on to a mirror and you look at the beam that
reflected from the mirror,i assume that you may also may damage your eyes
(like looking at sun that reflected from a mirror).
So,i was thinking,if the reflective screen have a metal coating and bead particles
(fiberglass),doesn't it act like a mirror and focus the projector light in a way
that it still might damage the eye(retina),in a level that close to the ability of the
reflected beam from a mirror might do?
No, because the light is deflected by those many beads and you are viewing the bounced light, not the direct light from the projector. The screen is not a mirror.Extraordinary claims require extraordinary evidence -Carl Sagan
It has nothing to do with whether the light is direct or reflected. It's the intensity. So theoretically, if the projector was bright enough and the screen reflected enough of that light to your eyes, yes it could cause strain/damage.
Remember, in the old days we all watched our home movies and slides by projector. I never heard of anyone going blind doing that.Extraordinary claims require extraordinary evidence -Carl Sagan
For all intents and purposes, barring unusual, specialty optics, no consumer or commercial TV, nor any projection is going to have the power to damage your retina.
Yeah, if you turned around and looked DIRECTLY into the beam of a powerful projector (especially if it was showing pure white) for more than a few seconds, it would probably make you see spots temporarily. TEMPORARILY.
But my professional recommendation to that is: don't do such a stupid thing.
Otherwise, you're fine either way. And shouldn't be further worried.
The original poster was worried about screens causing blindness. I have NEVER heard of anyone being blinded by looking at any kind of movie screen.Extraordinary claims require extraordinary evidence -Carl Sagan
IMO, eye strain has more to do with a screen being too close/too far away for the viewer's comfort, poor contrast, flicker, or excessively small text size than the type of screen. Screen brightness can usually be adjusted to be appropriate for the amount of ambient light in the room.Ignore list: hello_hello, tried, TechLord, Snoopy329
The outdoor sunlight causes more damage to your eyes than any other source of light within the visual spectrum, I wouldn't worry about TV. Back in the day refresh rate of old CRT TV's and monitors that was a concern, It caused fatigue to the eyes not the light itself.
Thanks again for all the replies.
I would like to mention that i wasn't refer to blindness from the screen,as
TreeTops mentioned.I referred to the possibility that the reflected light may kill,gradually,the retina receptor cells(loose sooner your vision)
which of course depend on how much are you exposed to it.
I come to that thought,since there is not any special warning/danger from any manufacturers/or eye's doctors about watching directly on the TV screen or tablets,pc screen etc.But there is always a big warning not to look on projector beam.
My concern is only referred to the grey reflecting one,not to the standard white 1.00 gain.The reflective screen that i was talking about is covered(among other thing)with metal coating,the screen is maybe not a mirror,but when i heard metal coating,i imagine how it is to look at the reflected light of the sun on a white
wall(no issue at all)between look on the reflected sun from smooth silver metal that dazzling you(big issue).So the beam of the projector(which is danger)reflected from a metal coating layer on the screen and focused to give higher brightness(in small angle).
I hope that,as you all explains,the reflecting light from those,metal coating reflecting screen,are really not harm at all especially not more than a tv screen and it is all depend
on the intensity of the light,which can be adjusted.
Thanks a lot for your help.