Does anyone know why this happens - Rainbow effect

[groovyman 0]

These screenshots are from different locations, but the same camera - CNB DFL-20S. It's a 600TVL 3.8mm fixed Mona Lisa camera. Seems like a rainbow effect is being picked up by these cameras with certain lighting conditions. I've also seen it with other CNB Mona Lisa cameras, but the DFL-20S is the most pronounced.

 

Does anyone know why it happens and what can be done to eliminate it? This doesn't seem to happen with any other cameras installed at these locations.

 

NOTE: Images cropped and zoomed in to show detail.

 

 

 

[the toss 0]

Have a look at the gain & chroma settings on the camera

[groovyman 0]

Have a look at the gain & chroma settings on the camera

Thanks, but these cameras don't have any configurable settings. I tried changing the color, brightness, contrast, hue, saturation & sharpness on the DVR with varied results. The effect remains no matter what I've tried. I've seen this same effect on other members screenshots as well. In some locations the effect was so bad I had to install different cameras.

[tomcctv 190]

CNB DFL-20S

 

 

these cameras are the basics from CNB. board camera fitted to a dome .... $45. and you have no settings to help setup (fixed mona)

 

 

NOTE: Images cropped and zoomed in to show detail.

 

you will not get much better using a fixed lens.

[shockwave199 0]

I think I've read it's the AWB setting that can help and since it's auto in that camera with no control to tweak it, there you have it. One of mine does that on certain things in the frame if the light is just right. I know you cropped the photo for a closer look, but those cameras seem to suffer the problem more than normal, to me.

[groovyman 0]

Thanks for the replys. The effect doesn't happen with all of, just a few. I can understand the reflection off bright surfaces, such as the silver racks that reflect light, but what really has me confused is the black grout lines. I've seen this effect very often on many different cameras when someone is wearing a shirt with thin lines though.

 

These locations have a mix of cameras and these were used as repalcements. Each location has fluorescent lighting, and the bulbs can be different from fixture to fixture. So, I thought that might be the issue.

 

Something I notice about these cameras is that they don't pick up the change in frequencies from the fluorescent lighting like some other cameras do. For instance, with some other cameras the lighting appears to get brighter and darker. It's very noticeable when reviewing video at 4x - looks like a light that keeps going from bright to dark and it can happen in different sections of the area being covered by the camera - one area gets bright while the other gets dark. With these Mona Lisa cameras that doesn't happen, but the rainbow effect is there. Choosing one over the other I'll choose the rainbow, but I'm not sure if I'll continue to use the DFL-20S because I never know when this is effect is going to happen.

 

Edit: just wondering if there's some sort of filter I can put on the plastic dome covers to block the absoption of those rainbow lines - like clear tinting that blocks UV rays. I know it's not UV rays, but just wondering if clear tint would make a difference. I'll try it and see what happens.

[MaxIcon 0]

I've seem color halos on rifle scopes and binoculars from an effect called chromatic aberration (essentially, multi-element lenses focusing the different color wavelengths at slightly different focal points), but it doesn't look quite like this. It's usually a purplish or reddish fringe along contrasting lines.

 

I'd try swapping lenses between a good camera and a bad camera, if they're easy to get at, to see if it's a lens issue vs a sensor issue. I could see either lens element alignment or sensor alignment causing this kind of problem.