There are two popular wavelengths of IR light for security cameras. One is 850nm and the other is 940nm. Which one is best for your camera depends on which CCD sensor is used in the camera. Some sensors are more sensitive to 850nm and others with 940nm. Which wavelength works best for Meraki cameras when using an external light source? I have MV21s right now. Are all Meraki cameras best with the same wavelength?
MV cameras use 850nm for their built in illuminators and that would be the wavelength I would recommend. We have deployed and tested PoE devices from https://www.rayteccctv.com/ and https://www.iluminarinc.com/
External IR illuminator makes a huge difference to all camera deployments and I would advise their use in any long range situation.
That is going to depend on application. My informal testing indicated that anything beyond 40 ft would benefit but it may not be required. I am trying to trigger motion alerts. At 70 ft there does not seem to be enough illumination to trigger motion with the internal IR leds, so I am going to try external illumination. A lot can impact the illumination, so it may just be specific to my situation.
Agreed @mwiener and @wey2go this is definitely a "your mileage may vary" type of situation, no two camera deployments are every going to have the same exact illumination conditions. If you were looking for a rule of thumb, from experience with my own customers, I'd say between 40 and 50 feet. But again, it's an "it depends" type of answer, in the example I used for my driveway MV71, it does improve the overall scene at night, both up close and out to 70-80 feet into the street.
@mwienerii I use a relatively cheap (US $25) 8-LED Univivi IR illuminator 850nm for my MV71 over my driveway and it works well and made a decent improvement. I did not do any testing with 940 nm to compare, but the 850nm worked great. The stock power cord was a bit short, so I also needed a short 12 volt 2.1x5.5 mm extension cable. Not sure the distance you're talking about, the longer the distance, the better (more expensive) illuminators you'll need. Hope that helps!