WHY oh WHY is an IP cam so much better for license plates??

[nightswatch 0]

I've been evidently just screwing around with my low light LG L322 low-light box cameras. For months now.

 

Then I finally try moving one of my Hikvision 2032 bullet and voila. Easy Peasy.

 

So.... why?

 

It can't be because it's networked.

 

It has to be the optics and/or the CCD.... right? I mean.... Whether it's analog or network, that's just an interface. I don't think these Hikvision 2032s are near as good with unassisted low-light as my 0.001 lux box cameras.

 

I've removed the mechanical IR cut filter from my camera and verified on my bench that it can see just as well in the dark when assisted with 850nm or 940nm IR illumination as the Hikvision can see. Yet... when I set up my analog to look right out of my garage and across the street, it sees hardly anything with either the 850 or the 940nm IR assistance.

 

I'm not going out any windows even. I just don't get it.

 

 

I do suspect that even the Hikvision 2032 bullet must be employing some degree of IR cut at night since it doesn't see the anything lit up by 940nm illuminator.

 

I just don't see why my low-light box can't capture pictures like I see of everyone else's license capture IP cameras.

 

I'm thinking that I ought to just put one of my 25mm lenses in one of my 2032s like I've seen someone else do on here and see how it functions for my license capture application.

 

I'm so frustrated.

 

Any ideas? Thank you in advance.

[SyconsciousAu 0]

 

Any ideas? Thank you in advance.

 

Does your analogue camera have Wide Dynamic Range (WDR) and is it switched on? Sometimes the camera will select aperture and shutter settings based on an area of high light in the frame which makes most of your image dark. WDR should get around this if your camera has it.

 

What lens are you using?

 

Claimed lux values on some cameras are often based on insanely large aperture lenses with really slow shutter speed. Remember each F stop you go up halves the amount of light getting through. If you camera minimum illumination is based on an F1.0 lens and you have an F2 Lens, you already 2 F stops down the way and only getting 1/4 of the light through.

 

What illuminator are you using? Testing on a bench is fine but in real world applications illumination drops off according to the inverse square law. A good rule of thumb is that every time distance doubles your illumination drops of to 1/4 of what it was.

 

So at 2m from your camera your illumination will be 1/4 of what it was at 1m, at 4m it will be 1/16, at 8m it will be 1/64 etc etc.

 

Not all camera's are sensitive to 940nm IR. You also wont see as far with 940nm as you will with 850nm.

 

Also for cheaper illuminators a good rule of thumb is to convert the claimed illumination distance in metres to feet and you will be in the ballpark of the actual real world performance.

[survtech 0]

One word: interlaced.

 

Most analog cameras deliver interlaced video. That is where one frame (actually field) of video contains the odd scan lines and the other contains the even scan lines. When an object is in motion, the resulting picture looks like this:

 

IP cameras deliver progressive scan video. That means all scan lines are contained in each image.

 

Shutter speed and image resolution also have an effect on the ability to deliver images of the license plates of moving objects but interlacing is a major culprit.