Led lights and any cube HD or higher solution camera or 2 all depends how large your fiddle yard is., there are plenty on ebay

John

Thanks for your comments.

Here is the problem:
I want a video camera that transmits in real time, covers an area of 3m long and 1m wide, possible at dim light conditions. The camera must transmit
the video via WiFi to my iPhone for instant monitoring.

Unfortunately even places like Amazon don't enable you to filter out the cameras which don't provide the requested conditions. And since there are pages and pages of cameras available it is for me too painful trying to go through them all. And regrettably these days local camera store employees don't know their arm from their elbow!

Pfalzbahn

May I ask you to elaborate on why this is "obvious"

While I might guess there is a distance issue, you do not indicate the distance to scope.
Power, (access to), is also a consideration.

Hiding a wireless transmitter under the layout may also expose you to noise from the surrounding digital track signal and dropout due to scenery being in the way.

The CS3 supports USB cameras (webcams) natively and you can then pick that up from any Ethernet attached device with a browser.
Here again I would generally steer clear of WiFi as IP is loosey and a cable is best

While generally I would not recommend bloating the CS3 with work load that is not directly related to actually running trains, this is a function solution.

Otherwise you could just search for "Baby minders"

What about using a vehicle reversing camera and monitor, either hard wired or wireless can be bought....cheap to.