I'm looking for a way to fix the slight misconvergence on my Epson 8350

CalculatinGenius said:

There dosen't seem to be a lot of information about projector misconvergence out there. I suppose its rare?
but anyways-- it appears that the 8350 entirely lacks the digital LCD alignment option its menu, which sucks because there's just a bit of color fringing that id bet could easily by remedied with software. does anyone know of a software that may allow me to split the color channels at the input side (my laptop) or maybe a way to unlock/ add this missing menu? with that fixed id say the 8350 is just about perfect for me. thanks in advance

Click to expand...

What is the source of the misconvergance exactly? Are you sure it's a panel alignment problem?

The point is that misconvergance propagation is not necessary the fault of panel alignment or panel alignment alone.

Chromatic aberration or spherochromatism is most often the source of color fringing. It's a function of the quality and design of the lens or lens assembly and the ability of a given lens to focus all colors to the same point.

Chromatic aberration can/will be present as either or both axial and transverse distortion. Different colors have different wavelengths and will focus at different positions in the focal plane as will the amount of distortion by wavelength for a given lens.

The lens shift mechanism and the amount or position of the lens shift can also introduce color fringing and or focus uniformity issues.

In other words, you could have a perfectly aligned panel(s) and still have color fringing.

Projectors are a kind of "you get what you pay" item and good glass in a lens is expensive. It's not unusual for a really good lens or the best lens of the same focal length as used in your Epson 8350 to cost twice as much or more than your whole projector.

Unless you have a serious problem, I doubt the fringing is much of a problem unless you're looking at a test pattern on the screen.

Color fringing can have the affect of a somewhat soft focus with normal program material. Projectors with electronic pixel adjustment can help, but typically do not produce 100% uniformity as it is still a lens quality issue.

b curry said:

What is the source of the misconvergance exactly? Are you sure it's a panel alignment problem?

The point is that misconvergance propagation is not necessary the fault of panel alignment or panel alignment alone.

Chromatic aberration or spherochromatism is most often the source of color fringing. It's a function of the quality and design of the lens or lens assembly and the ability of a given lens to focus all colors to the same point.

Chromatic aberration can/will be present as either or both axial and transverse distortion. Different colors have different wavelengths and will focus at different positions in the focal plane as will the amount of distortion by wavelength for a given lens.

The lens shift mechanism and the amount or position of the lens shift can also introduce color fringing and or focus uniformity issues.

In other words, you could have a perfectly aligned panel(s) and still have color fringing.

Projectors are a kind of "you get what you pay" item and good glass in a lens is expensive. It's not unusual for a really good lens or the best lens of the same focal length as used in your Epson 8350 to cost twice as much or more than your whole projector.

Unless you have a serious problem, I doubt the fringing is much of a problem unless you're looking at a test pattern on the screen.

Color fringing can have the affect of a somewhat soft focus with normal program material. Projectors with electronic pixel adjustment can help, but typically do not produce 100% uniformity as it is still a lens quality issue.

Click to expand...

the glass is fine. nothing changes regarding the fringing when I adjust the lens shift. the fringing is noticeable even from a viewing distance, especially with white text/objects

CalculatinGenius said:

the glass is fine. nothing changes regarding the fringing when I adjust the lens shift. the fringing is noticeable even from a viewing distance, especially with white text/objects

Click to expand...

While do I appreciate your position, and with all respect, the glass or in this case plastic lens is not fine.

It's a problem that occurs in all lens'. It's impossible to find a lens without chromatic aberration.

Higher quality, expensive lenses will minimize chromatic aberration better, but they do not eliminate it.

Your attached photo is a textbook example of "purple fringing". It's a purple ghost or halo appearing in a high contrast area. If you google "purple fringing" and or "chromatic aberration" you'll perhaps get a better understanding.

In general, from your pictures, you won't get an image much better than what you have at the price point of the Epson 8350.

EDIT: Even a single imager chip DLP will exhibit this phenomena and it has no panels to align as it's a single chip optical engine.

CalculatinGenius said:

I know what chromatic abberation is (I'm a photographer)
This isnt the same I think. No lens I've seen, even poor quality, produced chromatic abberation uniformly on the image like this. I would expect the fringing to be more messy and bloomy, like it is with poor quality lenses. yet I'm sure you noticed, the pixels themselves are razor sharp and more reminiscent of an intentional photoshop effect than lens fringing. I think it is just a slight misconvergence issue. Not catastrophic by any means, but slightly annoying nonetheless. Also, the 8350 has glass lenses as far as I know?

Click to expand...

Very simplistically...

If you note the vertical green line in the picture below, it's referenced as the "Focus Point". The best or most accurate focus is at the horizontal axis and the vertical intersection of all colored light frequencies (RGB) or "white light".

Blue light has the fastest frequency and tends to converge before the "Focus Point". Note the red light is converging just beyond the "Focus Point".

Where the red and blue light rays intersect at the focus point, but above and below the Best Focus Point, you have chromatic aberration.

In your case you see this manifestation as purple fringe, the combination of red and blue light.