Effect of ambient light on eyes when watching television

mkbh_10

One watched TV in ambient light to avoid strain on eyes. What role is ambient light playing and how can this be explained in terms of physics of photons which come from the TV and which come from ambient light.

Doc Al

This is more a question of biology than physics.

Fredrik

I don't think this has a lot to do with physics. It's about how eyes work. So this should probably be in the biology forum. Unfortunately I don't know enough about that to comment. Edit: That was quick.

Drakkith

What eye strain are you talking about? A TV should be so bright that you have no need to strain your eyes. On that note, what does "strain your eyes" really mean? I've heard the old story of don't read in dim light because of eye strain, but I have no idea why this would cause any eye strain.

Fredrik

Drakkith, I assumed that he (or she) was asking why it's uncomfortable to watch TV when all other lights in the room are off.

thorium1010

Basically when you strain, ciliary muscles contract in order for you to properly see. However over time it may give out and cause problems in vision.

http://en.wikipedia.org/wiki/Asthenopia

Drakkith

I wasn't aware that this happened to people.

Does this affect people who watch TV since you rarely sit at such close distances from it?

micromass

If the light conditions are bad, then it happens to me. If there is enough light, then I don't get troubles.

wiyosaya

This is addressed in at least one of the home theater display calibration discs - Digital Video Essentials HD Basics - http://www.sceniclabs.com/products/d...ials-hd-basics Others, like the Disney disc, may also address it; however, I have no experience with any of the others.

I have my "home theater" setup with background lighting as close as I can currently get to what is suggested, and both my wife and I find that it does decrease eye-strain.

As to a medical explanation, I am sure there is one, however, I do not know what that explanation is.

Evo

The only reference to a study I could find.

http://www.sciencedaily.com/releases...0425015643.htm

I think it varies between people. All of my life I read in dim light, I could read very well and bright light actually caused eyestrain and pain in my eyes if I was reading or on a computer. Now, just within the last few months, I've noticed that I have to turn lights on when I read or I have difficulty seeing the text. I've crossed over into "old eyes".

Drakkith

No Evo! Take my eyes!

Evo

Awwwwww, thank you, I guess I need to get some new glasses. The other night I needed to read some fine print and had to get a flashlight.

Drakkith

Well, I guess it's not too much of a problem until you need a spotlight!

Evo

Oooh, maybe I could buy a miners hat for reading, it has that flashlight in front. That's one of the reasons I wonder about those e-book readers like a kindle or ipad, I like reading in bed with little light, and it seems these pads would cause huge eyestrain unless you used it in a well lighted room.

Borek

Miners hat is a good idea, not only you will see better, but you will be safer while reading too (and knowing you making you safer is a good idea always).

IMHO some ambient light while watching TV helps for purely optical reasons - pupils contract and DOF increase, that means we are seeing better.