Shutter speed AND frame rate

[ak357 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.

 

"Red" IR against red number

I guess I don't expect lots reflection

 

that why I tried to invert and get not bad results

 

 

unless u guys have some other ideas

[rory 0]

I dont know .. I have no plates like that to test right now ..

 

here is that same image you posted though, equalized the number section:

[rory 0]

here is the image you posted, with contrast turned up:

[ak357 0]

here is the image you posted, with contrast turned up:

 

thx

but I have done this before

You know as well as me in real life we need to capture as is

Customers don't like to play

[Soundy 1]

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.

 

Well... sort of. The sensor is generating an image 30 times per second, in keeping with the video spec (technically, 29.97 times per second for color video, but that gets deeper into the nitty-gritty of NTSC spec and isn't really relevant to the discussion). The shutter activates UP TO once per frame, for the designated time period. The shutter speed can actually be LOWER than 1/30s... technically, in fact, the shutter can be open an infinite length of time - the image just becomes "smeared" across multiple video frames.

 

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??????

 

Nope. Frame rate, at least with analog cameras, is designated by the video format used (30fps NTSC, 25fps PAL - in both cases, based initially on the AC power frequency in the region of origin, 60Hz for North America, where NTSC is used, or 50Hz for most of the rest of the world, where PAL is used).

 

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

 

Nah, just sleepy - LONG day!

 

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

 

ROFL, nicely played

[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.

 

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?

 

You'll be lucky to use 1/30s at night. Consider that light is only hitting the sensor as long as the shutter is open - the less time the shutter is open, the less light gets through to the sensor. Every doubling of shutter speed means half the light.

 

Most cameras, assuming no trickery like signal boosting, and using a "typical" lens with a wide-open aperture around f/1.4, you'll need probably 1/1000s shutter in bright daylight. 1/2000s would be half the light transmission of that, meaning an image half the brightness. 1/4000 would be 1/4 the brighntess; 1/8000 would be down to 1/8 the light level, and so on.

[bike_rider 0]

I've written 2 posts to this thread that disappeared.

 

Anyway, shutter speed depends on what you are trying to shoot. How fast is it moving and what direction?

 

I use 1/1000 (I think) to stop 30 mph cross traffic. Works great in the day, but that camera is blind at night.

 

If you want to see what it takes to stop motion in front of your house, take some sample photos of passing traffic (during the day). Set your camera to manual shutter speed and try 1/250, 1/500, 1/1000 and 1/2000 (if you can - that's pretty fast). I bet you can do it on 1/200 - 1/500 or so if they are coming at you.

[rory 0]

I've written 2 posts to this thread that disappeared.

I dont see any event of a deleted, moved, or edited post for this thread or your username.

[zmxtech 0]

FYI.... you only need around 1/1000 to capture plates up to 100kph

 

1/100000 ? WTF ?

 

If its night blast the plate with IR. Put a 850 filter on it otherwise day-night focus shift will be bad.

 

 

my 2c

[bike_rider 0]

I've written 2 posts to this thread that disappeared.

I dont see any event of a deleted, moved, or edited post for this thread or your username.

 

Yeah, I think I must have been having a senior moment. I thought I pushed the button, but maybe not.

[C.O.P. 0]

Bike,

 

I think I remember you posting comments. Assuming I am not having a "senior moment", they wre probably in a different thread. I was trying to contain my questions (thus the answers) to one thread for a while but switched.

 

The idea of one thread was to minimize the need to describe and explain the conditions and purpose of the project I am planning to do. Often, when someone asks a general question such as, "what is the best _______", they get responses asking for more information and/or a military grade product costing thousdands of $$ . I figure I have been a big enough pain by now that the "major responders" have a clue what I am trying to do. Maybe I should put the link to my general thread in my signature... hmmm... BRILLIANT!

 

Brilliant enough for a shutter speed of 1/120,000!!! (reference to get back on topic) I here by lay claim to the term "120,000 idea/moment"!

 

The smaller, more specialized threads seem to generate more response. Because of the "view your posts" feature, I can put the information together pretty easily.

 

EDIT: Now that I think about it Rory, maybe you could do a sticky called "Before you ask for the best!" that gives us "noobs" an idea of what information (conditions, purpose, etc) is required for an expert to give you a decent response. Maybe you already have one but I never bothered to read it... after all who really bothers to read forums rules and stickies! (yes, that was supposed to be funny)

[Soundy 1]

The smaller, more specialized threads seem to generate more response.

 

Usually because answering the more "general" threads requires a lot more typing, and thus a lot more thinking. That can be straining for most of us!

 

EDIT: Now that I think about it Rory, maybe you could do a sticky called "Before you ask for the best!" that gives us "noobs" an idea of what information (conditions, purpose, etc) is required for an expert to give you a decent response. Maybe you already have one but I never bothered to read it... after all who really bothers to read forums rules and stickies! (yes, that was supposed to be funny)

 

Heheheh, another forum I'm on, oriented primarily to the "performance import car" market in BC, has a "Police Forum" where actual police officers participate... some questions are SO commonly repeated (like "I didn't sign my ticket, is it still valid?", which comes up at least weekly), and the cops got so tired of telling people to use Search first, that they actually came up with a custom emoticon for it:

 

Sad fact is, stickies and FAQs and search are seldom the first tools used... they're more often something that's referred or linked to once someone has asked the same old question AGAIN...

[cctv_down_under 0]

Why dont you just use a camera that has a dynamic shutter - the Bosch high end cameras have this feature -- TBH though the best effects will be had by using the extreme reg - it is amazing absolutley amazing ...but some cameras offer dynamic shutter so that it adjust according to detected moevement or light level.

[C.O.P. 0]

Now taking donations for my very own BOSCH REG L1 license plate camera!

 

If only money wasn't an issue.

 

I suppose if I bought 1 crappy camera this year and saved the rest of my budget for next year, I could get one.

[rory 0]

Now taking donations for my very own BOSCH REG L1 license plate camera!

 

If only money wasn't an issue.

 

I suppose if I bought 1 crappy camera this year and saved the rest of my budget for next year, I could get one.

 

 

Or, search for a 2nd hand Extreme CCTV Reg L1 camera .. same thing .. Bosch bought Extreme CCTV.

[C.O.P. 0]

Or, search for a 2nd hand Extreme CCTV Reg L1 camera .. same thing .. Bosch bought Extreme CCTV.

 

I heard about Bosch buying Extreme... from the Samsung tech, oddly enough.

It's a bit of a pricey camera to risk getting 2nd hand, isn't it?

Do you happen to know of any?

[C.O.P. 0]

Or, search for a 2nd hand Extreme CCTV Reg L1 camera .. same thing .. Bosch bought Extreme CCTV.

 

What's the best way to attach a rope to a Reg L1 and rip it off given:

Low light conditions

A mirrorless jeep

2 drunk guys

and no clue where there is a Reg L1!

[andy220 0]

Dear Gents,

 

I would like to bring this topic back.

I have some philosophic question.

For instance I have set electronic shutter by 1/50 on my CCTV camera with PAL video output. Full interlaced frame should by rendered for each 40 miliseconds (25hz period).

My CCD imager is exposed for 20 miliseconds by a light (1/50 shutter period).There is additional processing delay (readout from H&V registers, DSP processing, A/D conversion, etc.) on videochain between imager and PAL coding circuit hopefully shorter then remaing 20 miliseconds.

Then new frame from imager should be ready in memory before rendering of new frame (probably at Vertical blanking period??)

 

My question is at what time starts opening shutter related to videosignal timing?? Is there any relation? Does it make sense such detection from videosignal a such?

If not so does anybody have idea from what point indside or ouside camera can I detect exactly electronic shutter opening? I think CCD chip does not have any control electronic shutter pin.

Thanks

 

BR

 

Andy