Let's talk lighting for a few minutes...

[ssnapier 0]

Ok, I have a few Mobotix cameras (M-12's) that will be placed on roughly 35 foot high poles. These poles will also be getting LED lights, and the point of all this is to watch a fence line and the approach to that fence line (ideally I would like to see 60-100 feet beyond the fence). The wattage of the LED is unknown at this point, but I am looking at the 300W model from LEDtronics as my primary choice (link to that light). For my question I don't think that matters a whole lot but it might after I get my answer.

 

I have done some playing around in low light conditions to try and determine just how much real light you need to make a camera like this see well in the dark. The cameras can report on screen how much illumination it can see in each lens, and based on that figure combined with 7 or 8 attempts I have come to the conclusion that 2 lux is enough light to make the camera useful... not perfect, but useful

 

The lenses used were 8mm focal length with F value of 2.0 which gives me 45 degrees of horizontal viewing and 34 degrees of vertical. I understand the effects that lens choice has on clarity and distance and all of that, and my tests were all done in what I would consider the "ideal" range of the lenses that were on this camera which was between 50 and 75 feet away from the camera. Like I said, this was simply me trying to understand the point at which there simply isn't enough light to be useful to the camera and 2 lux seemed to be the cutoff point.

 

Also, just for the lighting nerds in the house 2 lux translates to just under .18 foot candles.

 

After all of that, my question is simple. Has anyone here done and type of testing or playing around to figure out something similar and if so were your results anywhere near my figure of 2 lux or is this 100% camera/lens dependent with no measurable way to compare apples to apples?

[NotoriousBRK 0]

Your results are *mostly* going to be related to the lens/sensor combo of that camera.

 

That being said, you're in the range of what many megapixel cameras require for a good image. It's been a while since I tested a Mobotix camera, they were known for doing very slow shutters in low light conditions, resulting in any motion being very blurred. So, I'm not sure if you tested while watching a moving object in the scene.

 

Also, for whatever rating you get, it's more than just "2 lux". 2 lux might be OK 50 feet from the camera, but at 500 feet, you'd need more light at the target (light disperses/scatters over distance).

 

For our cameras I spec 2lux on target per 100' of distance from the camera as my guideline.

[ssnapier 0]

Awesome, it is good to know that I was coming up with useful info because this was a VERY unscientific test!

 

I also discovered that playing with the exposure settings made some big differences too. The sweet spot seemed to be 1/5 on the low end and 1/4000 on the high end. I also told it to use the entire image when evaluating for adjustments.

 

Thanks for the feedback!

[ChrisL 0]

This is absolutely on a camera to camera basis, being a Pelco guy myself I am pretty familiar with their surevision line, which is absolutely amazing in low light / harsh lighting conditions.

 

Check out these video's, they are pretty awesome

 

Low Light: http://www.pelco.com/sites/global/en/sales-and-support/downloads-and-tools/video-gallery/surevision-outdoor-night.page

 

WDR: http://www.pelco.com/sites/global/en/sales-and-support/downloads-and-tools/video-gallery/surevision-office-day.page

 

Anti-Bloom: http://www.pelco.com/sites/global/en/sales-and-support/downloads-and-tools/video-gallery/surevision-traffic-night.page

 

If you check out the image in the top right, you can see the actual light measurement. P=Panasonic S=Sony A=Arecont (I believe its Arecont, not axis)