The screendoor effect is the grid you can see between pixels. It's really due to the screen. The Fresnel lenses add their own artifacts, by "smudging" the image

The screendoor effect is the grid you can see between pixels. It's really due to the screen. The Fresnel lenses add their own artifacts, by "smudging" the image, as if they were dirty. I agree that those artifacts are the ones which tend to bother me more, but both are noticeable and can be significant in the right (wrong?) lighting conditions.