Blue Roller

Rhodesy · Jan 3, 2019

Hi Guys,

Please can anybody help me to save me from bothering Andy @EMPIRETECANDY ?

If my video uploads, you will see I have a funny blue shadow rolling accross my screen. This is usually showing on the white vertical bars, but today it is showing on right hand white bar and on the bags of coal on the bottom left corner.

Please help

Rhodesy · Jan 3, 2019

Is this a setting that I have gotten wrong?

alastairstevenson · Jan 3, 2019

Rhodesy said:
This is usually showing on the white vertical bars, but today it is showing on right hand white bar and on the bags of coal on the bottom left corner.

That looks to me a bit similar to the type of effect when the light source is fluctuating at the same frequency as or an integer multiple of the frame rate of the camera.
Most common when using CFL or regular fluorescent light sources where the intensity follows each cycle of the mains power.
Low-cost LEDs lights can do this also when they use a simple power supply that does not create a steady DC supply but fluctuates with the mains.

Have you added any new lights or replaced any bulbs just before you noticed this effect?
I'm assuming it's new behaviour, that does not occur during the day time.
Have you rebooted the camera?

How is the camera powered?

As an experiment, change the frame rate of the camera and see if the bands move at a different rate.

xyvyx · Jan 3, 2019

Yeah, those look like small LED can lights. Many Dahua cameras have an anti-flicker setting... if yours does, try it:

https://dahuawiki.com/IPC/Camera_Configuration#Anti-Flicker

You can also run a test using a standard incandescent bulb w/ those overhead lights off & see if it changes.

Rhodesy · Jan 3, 2019

Thanks Alastair,

Yep, I changed the frame rate but with no joy.

Correct, it does not happen during the daytime.

Correct I have LED downlights (set on movement sensor), you may just be able to see in the overhang at the top of the video.

Camera location is fairly new and the particular LED lights do seem to be the problem now you mention it. If I leave these down-lighters on permanent setting, then also trigger the floodlight, the issue goes away.

Therefore, it appears you have nailed it. Unfortunately they are manufactured by Aurora and although they look like a GU10 bulb, they have a single diode set in them that I am not sure can be changed.
The lights are mains powered 240v UK electrics.

SouthernYankee · Jan 3, 2019

Multiple light sources blinking at different frequencies causes this problem. Turn off all the lights but the IR on the camera. Does it still blink. If so turn off the IR and use only ambient light. does it still blik.

xyvyx · Jan 3, 2019

Yeah, if it's just a single diode in series w/ the GU10 LED bulb, then they're basically running with 50hz pulsed-DC current. That's generally the cheapest, most simple way to power an LED bulb w/ AC current.. granted, the LED is itself a diode by nature, but the other also restricts the current. The camera's 50hz anti-flicker setting might help this.

If not, you might be able to get a full-wave bridge rectifier instead of the existing diode... they're not very expensive, although it might be more easy to find a bulb that doesn't flicker instead.

GBJ5006-BP Micro Commercial Components (MCC) | Mouser

Granted, the bulb might run too hot running at 240v DC, so the "pulsing" also acts like a duty-cycle so it runs cooler.

SkyLake · Jan 3, 2019

You could try setting the "Anti-Flicker" to the corresponding frequency. 50Hz or 60Hz. If you live in the US then try 60Hz.

Conditions -> Exposure -> Anti-Flicker

Rhodesy · Jan 3, 2019

Thanks all, I have just fiddled with all the setting including anti flicker. I have had limited results in as much as I can stop the Blue Shadow lowering my WDR from 50 to 44.
This has left me with a bit of a white out by the bags of coal and my step, although this is largely irrelevant as I can set the floodlight to last longer time also which then improves the whiteout condition.

I've added a clip of the new setting. Blue shadow no longer present but I notice my floodlight is harmful to my picture quality.

See next post for video, accidentally added the old one.

Rhodesy · Jan 3, 2019

Sorry for delay.

SouthernYankee · Jan 3, 2019

Motion activated flood lights will blind the camera while it attempts to adjust. That is the white out. Use fixed lighting if you are going to use a camera.

Rhodesy · Jan 3, 2019

Thanks Yankee, any tips on should it be fixed ir or permanent outdoor evening lighting?

I'm just looking at these:-
https://cpc.farnell.com/c/security-cctv/cctv/cctv-accessories/infrared-illuminators

The attached image is nearly 1am here (pretty dark to naked eye) and the street light goes out soon which was giving some road light. So this is as good as it gets.

We had a guy testing car doors other day and it was then I realised night image wasn't good enough at the road distance.

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Blue Roller

Rhodesy

Getting the hang of it

Attachments

Rhodesy

Getting the hang of it

alastairstevenson

xyvyx

Getting the hang of it

Rhodesy

Getting the hang of it

SouthernYankee

xyvyx

Getting the hang of it

SkyLake

Getting comfortable

Rhodesy

Getting the hang of it

Rhodesy

Getting the hang of it

Attachments

SouthernYankee

Rhodesy

Getting the hang of it