Best FPS at night question.

[trauts14]

In a situation where I want to monitor/record cars going down the street in front of my house (No LPR), what FPS is recommended? The IP cam will be 5 feet away from street with an IR illuminator a few feet above said camera. I was going to use a 6mm lens cam for a tight high quality pic of just the road and cars. I have no idea what FPS cams do best with at night when there are moving cars and people in the road.

 

[nayr]

FPS has absolutely nothing to do with it; 1FPS or 60FPS wont make a lick of difference..

its shutter speed your interested in, the higher the shutter speed the less light it gathers and the darker the image.. to get license plates in motion I have to use 1/500 at night and its unable to see human targets.. most cameras run 1/30 or less at night and thats never going to capture a car @ 20mph.

 

[Kawboy12R]

FPS doesn't matter much. 15 is more than enough. Even 10 should be plenty. All you'll need is one good shot of the vehicle while it's in the field of view. You're more interested in lowering exposure time to reduce motion blur at night. How fast you'll be able to set your camera while still having a reasonably noise-free picture will depend on the camera and the light available. You'll need a powerful external IR illuminator if you really want to freeze moving objects in the street without using a powerful white spotlight. 1/60th of a second is about the slowest you'd want to go to be able to recognize a vehicle make/model when it's driving by. 1/120th or 1/250th is better but you'll require really good light plus a good low-light camera to use those speeds at a decent zoom level and get a decent pic. A 3.6mm IMX322 cam can be quite decent in colour in auto mode capturing 40+ mph traffic with a couple of 500w halogen floods lighting the road from 60-80' away while being pretty useless with the big floods floods off. 1/60th is the fastest I like under an LED streetlight catching a mix of foot and vehicle traffic using a Hik Darkfighter and virtually no other light with 30mph traffic at 60-70 feet and a roughly 6mm lens length (hard to tell exactly with a varifocal).

Sooo, the answer is it depends totally on the cam, lens length, angle, distance to and speed of the traffic, and lighting. The closer the car to the cam the faster your exposure will need to be. Get a good low-light cam and add light til you're happy. Shouldn't be a problem getting decent car shots at 1/120th, especially if you're not shooting 90 degrees side-on. They'll still be blurry if they're up fairly close and moving quick but you should be able to tell make/model. People at 1/120th are pretty good unless they're on a bike or a dead run.

Out near the street though, adding a big glowing illuminator might attract more attention than you'll want. 940nm won't glow but won't give nearly the light per amp that an 850nm unit will give. If you go 940nm, get one that draws at least 4a. I've got a smaller one on order that I'll be experimenting with. My 4a 940nm unit is decent but is outperformed by a 2a 850nm unit.

 

[trauts14]

Thank you. The illuminator is 3A. I was looking at Hikvision 3MP HD Outdoor PoE Network Mini DS-2CD2532F-I-2.8MM WITH 6MM LENS, although after reading what you wrote I feel this cam cannot do the task? I have a few ACTi E73A I could try. I am not even sure if the Hik or my existing ACTi cams allow me to adjust shutter speed. Do most cams allow shutter speed adjustment?

The cam will be 8feet from the road and mounted approx 10 feet up a tree. The illuminator (850nm)will be slightly higher so cars/people do not see the faint red glow.

I felt 6mm lens would be best since I am focusing on a neighborhood street and only want to capture people and cars (no license plates).

If the Hik I mentioned will not do the job, any thoughts or suggestions are greatly appreciated. Thank you.

FPS doesn't matter much. 15 is more than enough. Even 10 should be plenty. All you'll need is one good shot of the vehicle while it's in the field of view. You're more interested in lowering exposure time to reduce motion blur at night. How fast you'll be able to set your camera while still having a reasonably noise-free picture will depend on the camera and the light available. You'll need a powerful external IR illuminator if you really want to freeze moving objects in the street without using a powerful white spotlight. 1/60th of a second is about the slowest you'd want to go to be able to recognize a vehicle make/model when it's driving by. 1/120th or 1/250th is better but you'll require really good light plus a good low-light camera to use those speeds at a decent zoom level and get a decent pic. A 3.6mm IMX322 cam can be quite decent in colour in auto mode capturing 40+ mph traffic with a couple of 500w halogen floods lighting the road from 60-80' away while being pretty useless with the big floods floods off. 1/60th is the fastest I like under an LED streetlight catching a mix of foot and vehicle traffic using a Hik Darkfighter and virtually no other light with 30mph traffic at 60-70 feet and a roughly 6mm lens length (hard to tell exactly with a varifocal).

Sooo, the answer is it depends totally on the cam, lens length, angle, distance to and speed of the traffic, and lighting. The closer the car to the cam the faster your exposure will need to be. Get a good low-light cam and add light til you're happy. Shouldn't be a problem getting decent car shots at 1/120th, especially if you're not shooting 90 degrees side-on. They'll still be blurry if they're up fairly close and moving quick but you should be able to tell make/model. People at 1/120th are pretty good unless they're on a bike or a dead run.

Out near the street though, adding a big glowing illuminator might attract more attention than you'll want. 940nm won't glow but won't give nearly the light per amp that an 850nm unit will give. If you go 940nm, get one that draws at least 4a. I've got a smaller one on order that I'll be experimenting with. My 4a 940nm unit is decent but is outperformed by a 2a 850nm unit.

 

[Kawboy12R]

That Hik would be down on my list of choices. So would the Acti. They would both work but you'd be more satisfied with other choices. If you wanted to hide the camera in a birdhouse or nook in the tree then pick something that can turn off the internal IR. 4mp Hiks and Dahuas can do that as well as the 2mp Dahua 4231 cams. Budget IMX322 cams like in my 4431 vs 4231 vs IMX322 shootout or Q's budget cam shootout can't without surgery. Best bang for the buck versatile lowlight camera at $180 at the moment is the Dahua starlight varifocal turret in nayr's review although a turret is slightly harder to hide than a little bullet.

 

[Kawboy12R]

Oh, and most cams allow shutter speed adjustment of some kind. Hiks do it decently on a schedule but you have to keep changing the schedule time for day/night changeover unless you can figure out how to script it and use a sunset/sunrise time source. I just got some 4x31 Dahuas but they seem to be similar- no way to easily lock a fairly fast maximum slow shutter time for night and keep things in auto for when light improves. Setting one for plate capture can be paradoxically easy. Just leave it on 1/500 all the time and you can get plates at night though not faces and it is fast enough to work well during the day time without over exposing for faces and also plates.