Update - Christie laser projector mis-registered?

[Jonathan Smiles]

Update continuing on from http://www.film-tech.com/ubb/f16/t003834.html

So the mis-convergence now appears to be fixed in the standard screens at this recently opened multiplex (October 2019) , which means it was not a glasses wearer issue but a setup and calibration issue.

The convergence is not pixel perfect and slight mis-convergence is seen on pure white text but not noticeable during normal content, also fixed is screen brightness and laser speckle.
Still some silver screen related feint rainbow vertical banding at times.

[Randy Stankey]

What about chromatic aberration?

Different wavelengths of light don't bend the same way when passing through a lens. (Or other medium.)

I have seen this effect in cameras and photographs where chromatic aberration causes a rainbow effect around the edges of objects in the image. I have also seen this in microscopes and photographic enlargers, etc.

Does this also happen in projectors? I am guessing that it does. Is this true?

If chromatic aberration does occur in projectors, would the effect appear more pronounced in a digital, laser projector?
Since the light source comes from three distinct colored lasers, each with their own narrower wavelengths, would we see more pronounced rainbows?

The way that chromatic aberration is controlled in optics that I know about is to use specially coated lenses and collimating lenses to bring the colors into alignment.
Is this true of laser projectors, too? I suppose so. No?

If all of the above is true then could we guess that the effects that Johnathan sees are because of poor collimation?
Is there even a way to adjust the projector's optics to correct it?

My theory is that, even if the convergence is pixel-perfect, chromatic aberration could still make it look like the projector is out of alignment.
Because it is a laser projector where chromatic aberration might be more noticeable, collimation adjustments might be more critical. (If they exist.)

I think of this because I was recently talking to a coworker who was using a binocular microscope to do his work and he couldn't make his scope focus properly.
When I looked through the scope, I saw that rainbow effect from chromatic aberration so I showed him how to properly clean and adjust the scope to make the problem go away.

Bottom line: Could the problem that Johnathan is seeing be occurring because the people at the theater need to clean and adjust their lenses in a similar way that I did for my coworker?

If they let the projector run out of alignment with convergence, etc., it's not unreasonable to think that they forgot about other things which might seem insignificant but could cause noticeable problems if left undone.

[Dave Macaulay]

There is some chromatic aberration with digital projector lenses but it's minimal and really only just visible at the corners. For what they want for these lenses, they had better be good!
I don't think that laser illumination is more prone to this. 3/6P projectors do emit single wavelength colours but the visible effect won't be very different... sharper edged misaligned pixels I suppose, but the offset would not change.
Phosphor lasers have pure blue light but red and green are filtered non-coherent light much like from a xenon source.

[Jonathan Smiles]

Can a 3p laser projector have pixel perfect convergence on a silver screen even with bright white text on a black background?

[Steve Guttag]

Pixel perfect? That is going to be dicey, except in the VERY center of the lens. You have a lens in there and a variation of wavelengths. A lot is done to mitigate the chromatic aberrations but depending on what you define as perfect alignment, that may be a bit tougher. I'd think you could get very good and probably better than xenon (just a guess). Red has generally been a problem (for me) to always, everywhere, get perfect.

[Randy Stankey]

There is some chromatic aberration with digital projector lenses but it's minimal and really only just visible at the corners. For what they want for these lenses, they had better be good!

I think I understand.

Simply put, there will be chromatic aberration in virtually any optical system and it would take extraordinary measures to completely eliminate all of it. Projector designers have already done a lot of things to compensate for it. It would take so much work, it would be so complicted and it would be so expensive to eliminate all chromatic aberration that it wouldn't be worthwhile.

Basically, we have reached the point of diminishing returns.

I was helping a guy at work who was complaining that he couldn't do his job because he couldn't see through his microscope.
When I looked through his scope, I saw all kinds of fringing and identified the problem pretty quickly.
The eyepieces of the scope were covered in facial dirt, dust and oily fingerprints. The objective lens was dirty and the diopter adjustments were all out of whack.

I showed him how to use the air gun (filtered and dried air) to blow out the dust. We cleaned the lenses with lens cleaner. I showed him how to properly focus the objective, set the diopters correctly and turn the zoom knob to get parfocal alignment. Within a few minutes, we were back in business and the guy could see through the scope clearly again.
Honestly, I see this a lot where I work. Just about every microscope that I have used has been way out of alignment and I find myself constantly having to clean and adjust them before I can start work.

I think that many people just don't know how to set their scopes properly and they use it as an excuse for not doing their work.

With that in mind, that's why I brought this up.
I wonder whether people at the theater don't know how to make these kinds of simple adjustments and are using it as an excuse for having a poor picture on the screen.

Cleaning and adjusting a lens or calling a technician to do it for you should be "Projection 101." Shouldn't it?

[Jonathan Smiles]

Well the improvement was short lived as the next screen I visited was not fixed and now the operator says there is no issue and nothing needs fixing, local staff know and acknowledge there is a problem.

The IMAX screen at this site has 1.43ish aspect ratio screen with 12 channel audio but the crazy part is in late 2019 it has opened with Dual 2K Xenon 1.9 projectors, the room looks like it was deigned for dual 4K Laser.