Shutter Speed 30mph

[bantham1 0]

What shutter speed would be best to minimize blur on vehicles on a 30mph street? I am thinking of setting it to 1/125? CNB VBM-24vf cameras. It is set to 1/60 and way too much blur now.

[Soundy 1]

Well, 30mph works out to 44 feet/s. With a 1/60s shutter, the car is moving .7333ft. (8.8") during the shutter's duration. That's some significant blur. 1/125 will cut that approximately in half (4.4") - probably still too much to get a clear view. If you can get it to 1/500s, you cut the movement down to barely 1".

[bantham1 0]

Thanks for the calculation. I will set it to 1/500 and see if I have enough light at night.

[D.V.S. 0]

On my CNB's I set the LENS setting in the menu to ESC instead of DC. No motion blur with any moving objects, day or night.

 

edit: Well some motion blurring at night. Car about 20mph on a moonless night.

 

Edited January 6, 2011 by Guest

[Baylab 0]

It depend on the definition of "blur", if you want to catch a readable number plate, the displacement of the vehicle IN THE IMAGE ( not along its moving direction, except the optical axis of your camera is perpendicular to moving direction) should be smaller than 10mm.

 

Roughly, 30MPH equal to 13.4m/s, if the angle between camera and vehicle moving direction is 20 degree. the speed of vehicle image is around 4.8m/s, so in order to get a readable image of number plate, a shutter speed of 1/480 sec. is the maximum ( only for the angle of 20deg, if you use different one, you might need to do more calculation).

[bantham1 0]

What do you all use for shutter speeds for cameras that are aimed at roads?

[cglaeser 0]

Car about 20mph on a moonless night.

 

Judging from the shadows, appears to have a street light as well.

 

Best,

Christopher

[bantham1 0]

1/500 seemed to produce too much noise at night. 1/250 still produces quite a bit of noise and is maybe a little better than 1/60 at night. It is a trade off: noise at night with because of a fast shutter vs blur during the day/night caused by a slow shutter low shutter. Don't know which to choose. I did notice a faster shutter speed of 1/250 and above puts all my cameras into b/w mode when 2 were in color due to external lighting.

[D.V.S. 0]

Judging from the shadows, appears to have a street light as well.

 

Yes. That's a shadow from a tree lighted by a street light 200 feet away. There is also a street light 40 feet in front of the car. The Cnb adjusts shutter speed very well automatically, at least in my application.

[bantham1 0]

You have the lens on ESC? Is there wash out during the day?

[bantham1 0]

Can you tell which cameras are at esc. Note that 4 are CNB's and the other 2 are not.

[D.V.S. 0]

If the term washout is meant as not being able to cope with brightness (sun) then no. Very sunny here in Hawaii. But my 2 outside cams have no view of the sky. I remember reading on this forum to set the cam on DC. Tried that and various shutter speeds, settings and resorted back to ESC. My cams are probably first generation. No gamma settings on mine.

[D.V.S. 0]

2 and 4 are not Cnb's.

[bantham1 0]

1, 4, 5, 6 are CNBS(Left to right, top to bottom).

[D.V.S. 0]

1 and 6 are on esc?

[bantham1 0]

1 and 2 on ESC. Rest on 1/250 and DC lens. 1 has a 70 watt metal halide and 3/6 have a 100 watt metal halide.

[D.V.S. 0]

Shoots. Half wrong on both of them xD. How's that DC working for you?

[bantham1 0]

More noise. I will see when daylight comes around. Camera 2 actually looks the best under IR with less noise than the rest but you can't tell with the crappy web snapshot. If esc works during the day, I will switch the rest except camera 3. I forgot, Camera 3 has no adjustments or OSD but the picture is pretty sharp for a low price camera (don't know what that one is set at).

[D.V.S. 0]

I don't like when moving objects are recorded and all you get is a blur. That's why I use the electronic shutter.

 

Here's the network cam I told you about, lighted by 18 watts of spiral fluorescent.

 

[rory 0]

If the term washout is meant as not being able to cope with brightness (sun) then no. Very sunny here in Hawaii. But my 2 outside cams have no view of the sky. I remember reading on this forum to set the cam on DC. Tried that and various shutter speeds, settings and resorted back to ESC. My cams are probably first generation. No gamma settings on mine.

No problems with the CNB's here on DC and we have sun year round also

Did you make sure the IRIS level was adjusted for your conditions? Though I havent had to adjust that on them yet either.I havent touched the shutter speeds.

[bantham1 0]

Not bad with some light. I may have to add some megapixel cameras sometime when the price comes down. For now I will get 3 more analogs. DVR can take up to 16 cameras so I have some room to work. Shutter speed by default is 1/60 on the CNBs. Pretty slow for moving objects/blur.

[rory 0]

1 and 2 on ESC. Rest on 1/250 and DC lens. 1 has a 70 watt metal halide and 3/6 have a 100 watt metal halide.

That would be much darker at night though?

If so have you played with the gamma?

 

Yeah I just downloaded and played back some video from a VCM-24VF on the road and there is blur as the cars pass, makes it kind of look like the whole image is temporarily out of focus well except for one side which is on the sidewalk, in this case though we masked off the street as only want to get the people on the sidewalk and that part is really clear.

 

They have alot of light so I wonder if I should go down there and knock it up to 1/125 ... hmmm .. bout now I wish that camera had the remote adjustments ... cause its right in the heart of the ghetto.

[D.V.S. 0]

Or set the lens to ESC and avoid the frustration xD.

[bantham1 0]

3 of the 4 CNBs don't have a gamma option. You should be able to get away with 1/125 and it will help with the blur a little. I am anxious to see how the esc works during the day. Better bring a side arm on that job as working on these things takes some time.

[rory 0]

ESC as in Electronic Iris? Dont know how well that would work at the location as it gets hit with alot of sun and car lights.

 

btw Hand guns are illegal here