Shutter speed AND frame rate

[C.O.P. 0]

I apologize if this has been answered somewhere already. I did a search but didn't see anything that seemed to answer what I am going to ask.

 

I spoke with someone from Samsung tech support today about using a mid ranged camera for license plate capture. He suggested I use a camera with an adjustable shutter speed that can hit at least 1/100,000sec. To that end, he recommended the Samsung SHC-737 that can go to 1/120,000sec.

 

My question is, is the effective shutter speed of a camera limited by the frame rate of the DVR card you are using?

 

If shutter speed is the amount of time the shutter is open, wouldn't a shutter speed of 100,000 mean the camera is taking 100,000 images per second?

 

IF I am correct above (some how I doubt I am), how would those 100,000 images per second be translated by a 30fps dvr card?

 

I know I am missing something here.

[ak357 0]

I apologize if this has been answered somewhere already. I did a search but didn't see anything that seemed to answer what I am going to ask.

 

I spoke with someone from Samsung tech support today about using a mid ranged camera for license plate capture. He suggested I use a camera with an adjustable shutter speed that can hit at least 1/100,000sec. To that end, he recommended the Samsung SHC-737 that can go to 1/120,000sec.

 

My question is, is the effective shutter speed of a camera limited by the frame rate of the DVR card you are using?

 

If shutter speed is the amount of time the shutter is open, wouldn't a shutter speed of 100,000 mean the camera is taking 100,000 images per second?

 

IF I am correct above (some how I doubt I am), how would those 100,000 images per second be translated by a 30fps dvr card?

 

I know I am missing something here.

 

may help

http://lmgtfy.com/?q=what+is+shutter+speed

 

http://en.wikipedia.org/wiki/Frame_rate

 

http://en.wikipedia.org/wiki/Shutter_speed

[C.O.P. 0]

I'll explain further...

 

I DID do a google search for the definitions of each. I did do a search of the CCTV forums. It seems I was unable to understand how or if one limits the other.

 

If the shutter is open for exposure 1/100,000 of a second, what happens to the 99,999/100,000ths of that second? Obviously the shutter is not closed the rest of the time. As an object is passing by the camera, the shutter repeatedly opens for exposure... probably not 100,000 in a second but more than 30 I suspect. So if the shutter opens... say 100 times per second (whatever that shutter speed is... 100??) for an exposure (image???) but the DVR only takes 30 images (frames???) per second, what happens to the rest of the exposures (images???)?

 

Does that better explain what I am asking? I took a quick look at the links you posted... Again, I am dense and/or lacking the vocabulary so I didn't see an answer (that I could understand anyway).

[Biphase 0]

I'll explain further...

 

I DID do a google search for the definitions of each. I did do a search of the CCTV forums. It seems I was unable to understand how or if one limits the other.

 

If the shutter is open for exposure 1/100,000 of a second, what happens to the 99,999/100,000ths of that second? Obviously the shutter is not closed the rest of the time. As an object is passing by the camera, the shutter repeatedly opens for exposure... probably not 100,000 in a second but more than 30 I suspect. So if the shutter opens... say 100 times per second (whatever that shutter speed is... 100??) for an exposure (image???) but the DVR only takes 30 images (frames???) per second, what happens to the rest of the exposures (images???)?

 

Does that better explain what I am asking? I took a quick look at the links you posted... Again, I am dense and/or lacking the vocabulary so I didn't see an answer (that I could understand anyway).

 

Be educated - Watch this video

 

Shutter speed = light exposure time for 1 image

 

Learn about dynamic range too..by the same odd guy.

[rory 0]

Thats the old and cheap way to do it, but most cctv cameras are electronic shutter, yes the zoom cameras and some others have manual adjustable shutter. best is to buy a License plate camera, designed for the purpose, which also handles the pitch dark or low light capture. If you have full light though then its alot easier and you can get away with a basic camera like he suggested, in fact, in many cases you could get away with almost any CCTV color camera, even a bullet, unless you are dealing with speeding cars on a highway. Night time is the difficult part in most cases.

[ak357 0]

 

Be educated - Watch this video

 

Shutter speed = light exposure time for 1 image

 

Learn about dynamic range too..by the same odd guy.

 

Thx for links

I save them and more for my "curios" sales forces

[ak357 0]

I'll explain further...

 

I DID do a google search for the definitions of each. I did do a search of the CCTV forums. It seems I was unable to understand how or if one limits the other.

 

If the shutter is open for exposure 1/100,000 of a second, what happens to the 99,999/100,000ths of that second? Obviously the shutter is not closed the rest of the time. As an object is passing by the camera, the shutter repeatedly opens for exposure... probably not 100,000 in a second but more than 30 I suspect. So if the shutter opens... say 100 times per second (whatever that shutter speed is... 100??) for an exposure (image???) but the DVR only takes 30 images (frames???) per second, what happens to the rest of the exposures (images???)?

 

Does that better explain what I am asking? I took a quick look at the links you posted... Again, I am dense and/or lacking the vocabulary so I didn't see an answer (that I could understand anyway).

 

At least you are curios enough to keep asking ???

here is small hint

your camera produce and feed your DVR also 30 Frames per second

keep thinking .....

[C.O.P. 0]

My brain hurts.

[rory 0]

My brain hurts.

Just put a speed bump on the road, or park a car in the middle of it, so they have to slow right down almost to a full stop, then slap up a 4-9mm IR bullet zoomed in on the plate and you are good to go!! Less head pains (oh wait, the car lights will glare at night killing that particular camera so you need to have a paint gun and hire someone to take the lights out)

[C.O.P. 0]

I watched the vids. They were pretty interesting. I'd say they covered enough to generate more questions but not enough to select "your own CCT system".

 

I'm still hazy about the shutter speed and frame rate.

If 1 shutter cycle produces 1 image = 1 frame and you have the shutter speed cranked to 100,000 (100,000 frames per second) but the camera only sends 30 fps... how does the camera know which 30 of the 100,000 to send? I just haven't seen anything that explains it.

 

Granted, at my level and application, it's not really important. I am just curious. I guess another google is in order!

[ak357 0]

I watched the vids. They were pretty interesting. I'd say they covered enough to generate more questions but not enough to select "your own CCT system".

 

I'm still hazy about the shutter speed and frame rate.

If 1 shutter cycle produces 1 image = 1 frame and you have the shutter speed cranked to 100,000 (100,000 frames per second) but the camera only sends 30 fps... how does the camera know which 30 of the 100,000 to send? I just haven't seen anything that explains it.

 

Granted, at my level and application, it's not really important. I am just curious. I guess another google is in order!

 

that good

don't give up

let simplify

ask yourself ?

how long is "frame" ? ( 1/30 )

and then try to compare how many times shutter will open and close during one frame time interval....

[ak357 0]

My brain hurts.

Just put a speed bump on the road, or park a car in the middle of it, so they have to slow right down almost to a full stop, then slap up a 4-9mm IR bullet zoomed in on the plate and you are good to go!! Less head pains (oh wait, the car lights will glare at night killing that particular camera so you need to have a paint gun and hire someone to take the lights out)

 

Rory What should I do ?

numbers on plates are RED

[Soundy 1]

I spoke with someone from Samsung tech support today about using a mid ranged camera for license plate capture. He suggested I use a camera with an adjustable shutter speed that can hit at least 1/100,000sec. To that end, he recommended the Samsung SHC-737 that can go to 1/120,000sec.

 

Good sales pitch. Did he also explain how shutter speed affects exposure? You'd need a ridiculously bright light on an object to obtain a usable exposure at that speed.

 

My question is, is the effective shutter speed of a camera limited by the frame rate of the DVR card you are using?

 

No; the two are unrelated.

 

If shutter speed is the amount of time the shutter is open, wouldn't a shutter speed of 100,000 mean the camera is taking 100,000 images per second?

 

Not necessarily.

 

For one thing, NTSC video is limited to 30fps anyway: the camera itself is still only snapping 30 pictures per second, but for each of those, the shutter is open - and the sensor is collecting light - for only 1/100,000 of a second.

 

IF I am correct above (some how I doubt I am), how would those 100,000 images per second be translated by a 30fps dvr card?

 

See previous paragraph. The camera is still only sending 30fps.

 

I know I am missing something here.

 

Double-shot of Crown. Helps make everything clearer.

[Soundy 1]

Rory What should I do ?

numbers on plates are RED

 

Move away from Alberta?

[Soundy 1]

I'm still hazy about the shutter speed and frame rate.

If 1 shutter cycle produces 1 image = 1 frame and you have the shutter speed cranked to 100,000 (100,000 frames per second) but the camera only sends 30 fps... how does the camera know which 30 of the 100,000 to send? I just haven't seen anything that explains it.

 

Each shutter actuation does not produce a frame of video. You're looking at it backward: the video's framerate is fixed. It will be 30fps (assuming NTSC analog video) regardless of whether your shutter speed is 1/100,000s, or 1s.

 

Are you familiar with photography at all? That may be a simpler way to look at it: every time you press the button on your camera, you take one image, completely regardless of what the camera's shutter speed is. The faster the shutter, the less "motion blur" you'll get, but the less light you get as well.

[rory 0]

Rory What should I do ?

numbers on plates are RED

 

We have no issues here with those plates, red writing on white background. Must be the cold up there

 

Seriously though, why is that a problem for you?

[C.O.P. 0]

K, I got it now.

My assumption was the shutter kept going independant of what the camera was sending. That's why I couldn't understand how the camera "selected" what images were used to fill those 30 frames.

 

I now see the reverse is true... the shutter is actuating/activating up to 30 times in 1 second with an exposure between 100,000 and 30.

Now we sort of get back to my original question... effective frame rates can be limited by shutter speed but NOT vice versa. If your frame rate is 30 but you shutter speed is less than 30, your effective frame rate will = your shutter speed??????

 

Soundy,

 

You should know by now I know next to nothing about photography, cameras and CCTV security except what I have learned from here.

PS. you seem a little short today. Bad day?

 

or

 

U shld no I no <0 pics cams CCTV sept wut I lrnd here.

[bike_rider 0]

Yes, if your exposure is 1/20 of a second, then you can't get more than 20 fps. That rarely is a problem because everything would be blurry at that speed, so I can't imagine anyone wanting that exposure for CCTV.

[C.O.P. 0]

I spoke with someone from Samsung tech support today about using a mid ranged camera for license plate capture. He suggested I use a camera with an adjustable shutter speed that can hit at least 1/100,000sec. To that end, he recommended the Samsung SHC-737 that can go to 1/120,000sec.

 

Good sales pitch. Did he also explain how shutter speed affects exposure? You'd need a ridiculously bright light on an object to obtain a usable exposure at that speed.

 

What would be a reasonable shutter speed to expect (use) at about 50 feet with say a seperate 150ft IR source (playing with angles to avoid reflection after the fact)? The Panasonics that you guys like so much (484 and 504) top out at 1/10,000. Barring exceptional conditions, will I even come close to using that at night?

 

This is also my first attempt at quoting.

Edited January 20, 2010 by Guest

[cglaeser 0]

Yes, if your exposure is 1/20 of a second, then you can't get more than 20 fps. That rarely is a problem because everything would be blurry at that speed, so I can't imagine anyone wanting that exposure for CCTV.

 

Some CCTV cameras offer slow shutter speed called Sens-up. The feature can be useful in low light when objects of interest are stationary or moving relatively slowly compared to the shutter speed. The Samsung SHC-745, for example, offers a slow shutter range to Sens-up 256x.

 

Best,

Christopher

[ak357 0]

Seriously though, why is that a problem for you?

 

Have a look

IR and Plate

 

[rory 0]

Seriously though, why is that a problem for you?

 

Have a look

IR and Plate

 

 

What kind of IR are you using, also what type of camera? Maybe its a different red then on the plates we have here. All our government plates are red letters with white background. Maybe its the camera? I only used the Extreme CCTV Reg camera for night time licence plate capture .. are you using that or is that something else? I wouldnt sit so close to the Extreme Reg camera with IR on though, could burn skin.

[ak357 0]

Seriously though, why is that a problem for you?

 

Have a look

IR and Plate

 

 

What kind of IR are you using, also what type of camera? Maybe its a different red then on the plates we have here. All our government plates are red letters with white background. Maybe its the camera? I only used the Extreme CCTV Reg camera for night time licence plate capture .. are you using that or is that something else? I wouldnt sit so close to the Extreme Reg camera with IR on though, could burn skin.

 

IR is from reg 840 nnm bullets

tried with few diff bullets

 

I was able to get good results if I invert video

Edited January 20, 2010 by Guest

[cglaeser 0]

What kind of IR are you using, also what type of camera? Maybe its a different red then on the plates we have here.

 

I don't think it's the IR or the camera. I'm guessing it's the color. I have an Axis 223M and RayMax Fusion 50. A very dark blue sweatshirt that I own appears bright white and much brighter than a medium pair of blue jeans. I've seen various dark deep colors reflect the IR very brightly and while some lighter colors don't reflect much IR.

 

Best,

Christopher

[rory 0]

What kind of IR are you using, also what type of camera? Maybe its a different red then on the plates we have here.

 

I don't think it's the IR or the camera. I'm guessing it's the color. I have an Axis 223M and RayMax Fusion 50. A very dark blue sweatshirt that I own appears bright white and much brighter than a medium pair of blue jeans. I've seen various dark deep colors reflect the IR very brightly and while some lighter colors don't reflect much IR.

 

Best,

Christopher

 

Yeah but thats why we pay extra for the Reg cameras. .. its not your standard IR, its totally different build. not sure about the reg bullet though. Id have to check but im pretty sure we had no problems with any color plate here. Its been a while though.