Well, I have worn glasses and or contact lenses all my life. For the past few years I have owned CRT projectors but not until this year did I really get the time to fully set one up and observe how everything really works. Normally, with everything going on I don't usually get to play with the HT until after 9:00 at night at which time my eyes are already pretty tired. So, after wearing contact lenses all day I usually take them out and put on my glasses. Maybe I am the only one with this problem but last night while touching up some convergence I noticed something strange. I was seeing what appeared to be convergence errors with my glasses on. If I moved my head from side to side the error would appear on whatever side my eyes were turned away from. I can't believe I never noticed this before and it made me quickly realize that I should not be doing convergence and setup while wearing my glasses. As a matter of fact, I could visually correct or create a convergence error anywhere on the screen depending on the relationship of my head and eyes to the screen. I guess it makes sense kind of like the relationship of the raster to the convex and concave lens surfaces. Turning my head with my glasses on was kind of like adjusting Schiempflug on a projector, changing the relationship of my vision field to the lenses of my glasses. If this is totally obvious to others of you that wear glasses then I apologize but I found it interesting last night. Who knows how many nights I spent fighting what looked like convergence problems. :rolleyes:

Interesting, I'll have to look with my glasses off next time.

I found this information which might partially explain what is going on with me.

Accommodation-Convergence Relationship

When the eye adjusts focus for the near point, it's called accommodation. At the same time, the eyes turn in a certain amount towards each other so as to point at the same object. The relationship between these two movements gets thrown off with glasses; because of the compensation of focus, the amount of accommodation is greater or less than what the eyes are used to with a certain amount of convergence. When glasses are worn regularly, the eyes get used to the off-balance relationship and may have a harder time focusing without glasses, or the person may even develop convergence disorders.

Discouragement of Eye Movement

By nature, glasses are placed over the eyes such that only the center of the lens is at a right angle to the eye's line of sight. When the eye turns at all, it's looking through the lens at an angle, resulting in some distortion and loss of clarity, so the person is subtly encouraged to fix his gaze through the center of the lenses instead of freely moving his eyes in all directions. This immobility leads to tension and loss of the constant movements that are a key component in the function of perfect vision.

WIth -7 glasses/contacts, I'm legally blind without them. I had the flu one year for about 3 weeks back in 1999, and had to sit on the couch watching daytime TV. I thought I had done a good job converging, but it took me about 20 minutes to figure out that the edge misconvergence was due to my glasses (I wear contacts usually, but due to the flu and sleeping a lot, I wanted to wear glasses.

I finally threw a 27" TV on the coffee table and watched that from 6" away to give me that big screen effect :D

WIth -7 glasses/contacts, I'm legally blind without them. I had the flu one year for about 3 weeks back in 1999, and had to sit on the couch watching daytime TV. I thought I had done a good job converging, but it took me about 20 minutes to figure out that the edge misconvergence was due to my glasses (I wear contacts usually, but due to the flu and sleeping a lot, I wanted to wear glasses.

I finally threw a 27" TV on the coffee table and watched that from 6" away to give me that big screen effect :D

Didn't you listen to your mom? Sitting that close to a TV is the second most common cause of blindness! (Apparently, you are familiar with the first! :D:D:D )

dropzone,
You are definitely not just seeing things :). This is a common problem. I have noticed it mainly on peripheral areas. No-line bifocals make the situation worse. I believe the effect is caused by each color refracting differently as they pass through the lens and the changing angles between your eye and the lenses as you look through them at the outside edges. Contacts don't have this problem since the angle never changes between the eye and corrective lens.

I could really just kick myself for not getting Lasik surgery already. My ex-wife was in the optical field and I could have had the procedure done for free at one point! Ahh, I guess I will have to work it into my flex spending budget for next year maybe.

Jerry is right. This is a color-refraction issue. Your glasses are not color-corrected like a good camera lens. (Fortunately they're also not as big or heavy as a camera lens. :)) In the center they're normally OK, but at the edges (assuming you're near-sighted) the lenses get thicker and the color refraction index changes.

Try looking at a magenta line on a black background on your PC monitor sometime. If I look at it through the center of my lenses, it's a nice magenta line. But if I look through the edges of my lenses, it completely diverges into red and blue. (Red and blue are at the opposite ends of the spectrum so they have the greatest difference in refraction.) You can imagine what this does to your perception of a converged projector!!

The real pisser as that this doesn't just affect magenta lines. It affects EVERYthing to varying degrees. My vision is sharpest in the center of the lenses, but since the colors diverge at the edges, my overall vision is crap at the edges. It also creates a lot of eyestrain if you're not looking through the centers. Add that to my bad astigmatism (which among other things causes blurred vision and eyestrain if I tilt my head!!) and it's a real PITA. I'm sorely tempted to get LASIK even though I'd still have to wear glasses. At least my vision would be much better so I wouldn't suffer from all these issues.

It is all chromatic abberations which all lens have including our glasses.
When I do convergence I stay close to the screen and move across to be close to where I am doing the work.

If I don't have glasses on, I can't do anything. My eyes were bad enough to keep me out of the military at the height of Vietnam and they're worse now. Someone once remarked that if he ever got into a fight with me all he had to do to win was grab my glasses and I would be unable to see him, and he was right. I can see clearly without glasses so long as I'm within 4 inches of what I'm looking at - how hard would it be to do convergence at that distance?

Minolta makes a convergence meter that comes with a camera which comes up on Ebay once in a while. Is this meter (I think it's called CC-110) worth investing in to do crt FP convergence? Any others?

Minolta makes a convergence meter that comes with a camera which comes up on Ebay once in a while. Is this meter (I think it's called CC-110) worth investing in to do crt FP convergence? Any others?

Sounds like the ACON cameras. I'm up to trying anything that might help. My eyes are not the best for geometry but I find that I get better with each attempt.

There is one on the bay right now.

http://img.photobucket.com/albums/v641/dropzone7/1339211.jpg

Here is a PDF brochure on it.

http://www.konicaminoltaeurope.com/fileadmin/user_upload/Products/Industrial_Products/PDFs/en/CC100_110.pdf

Does that mean you should not be watching a movie while wearing glasses?

Deron.

You wuss....You need to train with these. If you conquer these you will be able to converge under any condition:)

http://gallery.avsforum.com/data/509/medium/bigclip.jpg

Does that mean you should not be watching a movie while wearing glasses?
I wondered when somebody was going to figure that out. :) Yes, if you see convergence errors when converging, you have exactly the same chromatic aberration happening when you watch the movie. Presumably it hasn't bothered you so I wouldn't worry about it.

dropzone7, IMHO that CC-110 is massive overkill for a hobbyist. You can DIY something that will do roughly the same effect without all the whizbang, just by pointing a video camera at the screen and blowing up the pixels on a monitor. That can be real handy for adjusting the magnetics (where you have to be back at the projector). But for doing convergence, you can stand right next to the screen. Your eyes will do the job just fine. Just be careful to look through the center of your lenses when you adjust.

You wuss....You need to train with these. If you conquer these you will be able to converge under any condition:)

http://gallery.avsforum.com/data/509/medium/bigclip.jpg

I gotta get me some of those! :D

Well I guess I know what I'm doing tonight.

I've never had any trouble with my glasses - they don't have the chromatic aberation.

I'm mildy shortsighted, but I can't wear contacts as they DRIVE ME BANANAS as I have irritable eyes, and I'm just too lazy to clean them and get then in and out.

As for Lasik, well, I could get it done cheap (my wife's a theatre nurse and assists eye surgeons sometimes), but my eyes still change slowly. So 5 years later I'd be in glasses again, and I don't want anyone messing with my eyes. You can get complications, a mate's wife took over a month to heal and one eye didn't work out well anyway.

I can't stand glasses for that very reason. That and the fact that you only see 20/20 in a tiny space, and there's no way I would wear those goofy glasses that take up your entire face. Curt probably wears those though :D.

Contacts are 100 times better, but sometimes they fall out or get stuck in the corner of my eye.

I've never had any trouble with my glasses - they don't have the chromatic aberation.

Are your lenses made with real glass?

The newer superthin poly lenses seem much worse for Chromatic Aberration (http://en.wikipedia.org/wiki/Chromatic_aberration)

But worth the trade-off in getting rid of the coke-bottle thickness and much lighter weight.

Very true. I can't use most of the high-index plastics because they cause too much of the edge distortion (caused by chromatic aberration). Glass would be ideal optically but would be much too heavy.

Are your lenses made with real glass?

The newer superthin poly lenses seem much worse for Chromatic Aberration (http://en.wikipedia.org/wiki/Chromatic_aberration)

But worth the trade-off in getting rid of the coke-bottle thickness and much lighter weight.

No, my glasses are polycarb. I'm mildly short sighted, with nothing else going on (astigmatism or anything). The number 1.75 rings a bell..I can squint and read the alarm clock across the room at night - I'm not blind as a bat like Curt :)

I've never noticed misconvergence due to my glasses.

I don't see why it would matter actually. You should be standing right up at the screen looking through the centre of the lens..

Cheap lenses = chromatic abberation = misconvergence errors with glasses.

Of all of the properties of a particular lens material, the one that most closely relates to its optical performance is its dispersion, which is specified by the Abbe number. Lower Abbe numbers result in the presence of chromatic aberration (i.e., color fringes above/below or to the left/right of a high contrast object), especially in larger lens sizes and stronger prescriptions (±4D or greater). Generally, lower Abbe numbers are a property of mid and higher index lenses that cannot be avoided, regardless of the material used. The Abbe number for a material at a particular refractive index formulation is usually specified as its Abbe value.

In practice, ABBE’s effect on chromatic aberration can be roughly estimated to change 1:1, meaning a change from 30 to 32 ABBE will not have a practically noticeable benefit, but a change from 30-47 could be beneficial for users with strong prescriptions that move their eyes and look ‘off-axis’ of optical center of the lens. Note that some users do not sense color fringing directly but will just describe 'off-axis blurriness'. Abbe values even as high as that of (Vd≤45) produce chromatic aberrations which can be perceptible to a user in lenses larger than 40mm in diameter and especially in strengths that are in excess of ±4D. At ±8D even glass (Vd≤58) produces chromatic aberration that can be noticed by a user. Chromatic aberration is independent of the lens being of spherical, aspheric, or atoric design.

Make sure you tell you optometrist that you will not accept lenses that produce chromatic aberration!

Stay away from any shop that promises glasses in less than a week.

Vern

I have Carl Zeiss lenses which are fairly heavy but I didn't want plastic lenses when I'm watching my PJ. I'll have to check if they cause any problems, it's not like I'm blind without them, but with them the picture is a little sharper that's for sure.

The only reason why I got them was because my PJ never looked focused to me so one day I just happened to pull up in front of an optometrist office at a mall and so I went in and had my eyes checked. Things were definately sharper after I got the glasses, but I payed alott more for the CZ lenses.

"My projector is HD, but my eyes are SD!"

I noticed this effect the instant I started to do convergence. What's interesting is that I've found the effect is exaggerated greatly with my CRT RPTV; while a bright white to dark transition at the same distance and location vs. my vision center on a sheet of paper will have a fringe of width N, the same thing shown on the RPTV has a fringe two or three times as evident. If I watched the RPTV with the same FOV as my PJ I'd be hosed!

I imagine there would be a type of mild paralax error too. I've noticed the same using my telescope for stargazing.

Now I use a camera which relays the image to a projector :) (digital!)

Without glasses on I can walk right up to the screen with a dot pattern up and perfectly converge my projector. Then if I put up a cross hatch and look at it from the seated position with my glasses on, it looks as though the blue is a half a line high. Take the glasses off and it looks perfect. Red to green is fine.:confused:

Chip

Damn, so does one converge it for the 4 eyed people or for the 2 eyed people.

Without glasses on I can walk right up to the screen with a dot pattern up and perfectly converge my projector. Then if I put up a cross hatch and look at it from the seated position with my glasses on, it looks as though the blue is a half a line high. Take the glasses off and it looks perfect. Red to green is fine.:confused:

Chip

Same here. I guess it does not help that the blue is defocused more than the other tubes as well.

My best "upgrade" of my hometheater, so to say, was when I got glasses about two years ago. I am slightly shortsighted with some astigmatism. Probably have had this fore more than 15 years but it has only slowly gone worse. Usually only wear my glasses for driving, bicycling etc and hometheater.

Watching movies with glasses was like going from SD projection to HD!! My misconvegence was so much more apparent also though.... But for convergence work I'd have to take my glasses off, since for me everything has a slight "shadow" at close range (< 1,5m) with glasses on.

I checked out my convergence last night with and without my glasses and I see no difference whether I look straight on or sideways through my glasses. I guess these CZ lenses work.

Hi guys.
If anyone knows.
Would antiglare coating help or worsen chromatic aberration?
Thanks

No effect. Anti-glare coating is a surface treatment to reduce reflection. Chromatic aberration is a refractive property of the lens, i.e. it's internal to the lens so no coating will affect it.

Thanks Gary