IQeye day/night cameras switch from day mode to night mode, based on ambient light levels.
This is the default behavior, that can be controlled in the Setup >Advanced tab of the camera web interface.
The ambient light level is measured by the amount of electronic gain that the camera applies.
The gain range is from 0.000 in bright daylight to 1.000 in complete darkness.
The current gain can be made visible in the image by using $IMGDBG in the ‘overlay text’ in the Setup > Basic tab.
Some parameters will appear in the image, and the second from the left is the gain, and it should be between 0.000 and 1.000
The default gain level for the camera to switch to night mode is 0.95
The default gain level for the camera to switch to day mode is 0.80
These are different thresholds to create a hysteresis, to avoid continuous switching during dusk and dawn.
What happens when the camera reached gain 0.95 is that the IR light cut (IRC) filter is removed from the imager.
This will cause distorted colors, so the camera switches to a black and white image for better contrast in night images.
When the IRC filter is removed, the sensor is also sensitive for IR light, so IR light can be used to illuminate the scene.
When the gain goes as low as 0.8 the camera will go back to day mode.
The IRC filter is moved back in place, and the camera will switch back to color images.
The following issue can occur when using strong IR illumination.
When the camera goes to night mode, suddenly the sensor becomes sensitive for IR light.
The camera will receive a lot of IR light, and will adjust its gain accordingly.
If the IR light is strong enough, the gain will go below 0.80
The camera will now go into day mode, as it now is below the day switching threshold of 0.80
The IRC filter is put in place, and the camera will no longer be sensitive for IR light.
The gain now goes up again to above 0.95 and the camera will go in night mode again.
This will repeat itself over and over again, and the camera will switch every few seconds.
This obviously is an undesirable situation and the following steps can be taken to correct the situation.
- You can use IR light of a lower intensity, or re-position the IR illuminator so that the camera will not go in day mode.
- Instead of letting the camera switch day/night based on ambient light, you can use a timer to switch day/night based on time of day.
You can set this in the Setup >Advanced tab of the camera web interface.
It is often undesirable to use the timer, as the correct day/night switch times change with the seasons during the year.
- You can use the input contacts of the camera, to control the camera day/night mode externally.
You can set this in the Setup >Advanced tab of the camera web interface.
Select mode ‘dayclose’ or ‘dayopen’ depending on the type on input contacts.
Of course, the contacts must be wired to an external device that provides proper day/night switching times.
- You can also modify the day switch gain threshold of the camera.
The default is set to a gain level of 0.80 for the camera to switch to day mode.
You can change this threshold to a lower value, for instance 0.70
You can do this by using the following URL in your browser:
http://x.x.x.x/set.oid?OidTB1.2.32.9.1=0.7 (Where x.x.x.x is your cameras IP address)
If the browser is not already logged in, it will ask for the camera log in credentials (default: user root password system)
You can see ALL possible cameras OID (Object Identifier) when using http://x.x.x.x/oidtable.html
Scroll down to ‘1.2.32.9.2 - IR filter auto-switch day point’ to see your current values.
You can find the correct day switching threshold as follows:
Set the camera in ‘force night’ in the Setup >Advanced tab of the camera web interface.
The camera will go in night mode, regardless the ambient light level.
Make sure the IR illuminations is on and is positioned correctly.
Read the current gain, using the $IMGDBG overlay in the image (or look at ‘1.2.32.9.1 - IR filter auto-switch current value (read only)’ in the oidtable.html)
Make sure you cycle the ‘mode’ back to ‘auto’ instead of ‘force night’.
If the current gain is for instance, has a value 0.78, you want to set the new day switching threshold gain just under that, for instance 0.75.
In night mode, the IR illumination will not push the gain lower than 0.75, so the camera will now remain in night mode.
Note 1:
There are several methods of setting the OID values.
- You can use the URL method as discussed above: http://x.x.x.x/set.oid?OidTB1.2.32.9.1=0.7
- You can also telnet into the camera and use the command: oid set 1.2.32.9.2 0.7
- There are also utilities such as IQmanager that allow you to set OID values.
Note 2:
The example above is for the current generation of cameras.
The previous generation of cameras (i.e. IQ75x cameras etc) cannot work with the $IMGDBG image overlay.
For these cameras you can use a text overlay $O(1.2.8.7)/$O(1.2.8.24) for similar functionality
This will show gain/shutterspeed values in the image.
Contact the IQeye support team for questions: support@iqeye.com
Note 3:
There is a tool called IQexposure that visualized the current day/nigh thresholds, and it allows easy adjustments with the threshold sliders:
It can be downloaded here:
https://www.dropbox.com/s/oj1ma5o9wy9vxto/IQexposure1.7-Installer.zip?dl=0