bigredfish
Known around here
Gotcha. I don’t think you can power an Illuminator from the camera itself. It will require its own power source.
IPC-HFW5231E-Z12 LPR from 137 feet
- Thread starter crc2004
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J Sigmo
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- Feb 5, 2018
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IR light, being longer wavelengths than the range of visible light, will be refracted differently by a lens than the visible light. Even within the visible spectrum, different wavelengths focus to different planes, so lens designers use multiple elements, different element materials, and special coatings to try to correct this so-called chromatic aberration.
My old manually-focused SLR lenses all have a small red dot to indicate where to set the distance scale (focusing ring scale) when shooting ifra-red film to get proper IR focus.
The idea is that you manually focus looking through the viewfinder, then move the lens focus distance ring setting (as indicated by the main focus reference line) over to the small red dot that indicates the approximate IR focus point. That corrects for this for you because you can't see the IR light, and thus, would otherwise end up with inaccurate focus for your IR film.
Earlier in this thread, people have stated that the cameras do a re-focus when switching between day and night modes. And that may well be because the IR filter mechanically switches in and out of the optical path.
Several things occur to me.
The refocus might happen on purpose in the firmware to force the camera to refocus to accommodate the different focus plane for operation with IR versus visible light. So this might be necessary, and thus done in the firmware to make the images better in most cases.
The refocus might happen simply because as the filter swaps in or out, it confuses the autofocus, with the image suddenly being very out of focus for a moment as the filter moves.
Forcing a fixed focus by disconnecting the focus motor's drive signal might work (after first getting focus set properly) but it might not be good given that you may want a different focus adjustment to account for the difference in focus setting needed for IR versus visible light. And if you were going to disable the AF motor, you should probably adjust the focus for the IR mode rather than the daylight mode because in daylight you're probably using a smaller aperture, and thus have greater depth of field, making the focus setting far less critical. At night, you may be running the lens "wide open", which makes focus far more unforgiving.
Ideally, the cameras would get a firmware update that allows you to remotely (programmatically) set the focus to a particular focus setting, but still be able to disable autofocus. That way, your day/night profile could set the focus to separate presets for day and night just as you'd want to use different presets for aperture and shutter speed.
Here's a crummy cell phone photo of one of my old manual-focus SLR lenses to show the special IR focus mark:
The arrow points to the small red dot that one uses for focusing when shooting infra-red film. Note how it's displaced a bit from the main focusing mark (the orange line). This shows the approximate difference in focus plane between IR and visible light for this lens.
Also note the aperture indications on that same part of the lens barrel. See how the two f/22 marks are widely spaced, while the two f/4 marks are in closer together. These marks are simple guides to show the approximate range of acceptable sharpness when using the indicated apertures. See how wide the depth of field is at f/22 as compared with f/4. Shooting at a small aperture makes focus so much more forgiving!
My old manually-focused SLR lenses all have a small red dot to indicate where to set the distance scale (focusing ring scale) when shooting ifra-red film to get proper IR focus.
The idea is that you manually focus looking through the viewfinder, then move the lens focus distance ring setting (as indicated by the main focus reference line) over to the small red dot that indicates the approximate IR focus point. That corrects for this for you because you can't see the IR light, and thus, would otherwise end up with inaccurate focus for your IR film.
Earlier in this thread, people have stated that the cameras do a re-focus when switching between day and night modes. And that may well be because the IR filter mechanically switches in and out of the optical path.
Several things occur to me.
The refocus might happen on purpose in the firmware to force the camera to refocus to accommodate the different focus plane for operation with IR versus visible light. So this might be necessary, and thus done in the firmware to make the images better in most cases.
The refocus might happen simply because as the filter swaps in or out, it confuses the autofocus, with the image suddenly being very out of focus for a moment as the filter moves.
Forcing a fixed focus by disconnecting the focus motor's drive signal might work (after first getting focus set properly) but it might not be good given that you may want a different focus adjustment to account for the difference in focus setting needed for IR versus visible light. And if you were going to disable the AF motor, you should probably adjust the focus for the IR mode rather than the daylight mode because in daylight you're probably using a smaller aperture, and thus have greater depth of field, making the focus setting far less critical. At night, you may be running the lens "wide open", which makes focus far more unforgiving.
Ideally, the cameras would get a firmware update that allows you to remotely (programmatically) set the focus to a particular focus setting, but still be able to disable autofocus. That way, your day/night profile could set the focus to separate presets for day and night just as you'd want to use different presets for aperture and shutter speed.
Here's a crummy cell phone photo of one of my old manual-focus SLR lenses to show the special IR focus mark:
The arrow points to the small red dot that one uses for focusing when shooting infra-red film. Note how it's displaced a bit from the main focusing mark (the orange line). This shows the approximate difference in focus plane between IR and visible light for this lens.
Also note the aperture indications on that same part of the lens barrel. See how the two f/22 marks are widely spaced, while the two f/4 marks are in closer together. These marks are simple guides to show the approximate range of acceptable sharpness when using the indicated apertures. See how wide the depth of field is at f/22 as compared with f/4. Shooting at a small aperture makes focus so much more forgiving!
- Nov 25, 2016
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What settings on BI are you guys using at night to trigger recordings on the Z12. Daytime is picking up every car that passes but last night after I got the camera dialed in and could see the plates, there aren't any triggered recordings.
- Nov 25, 2016
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In all likelihood there isn't enough motion in the nighttime frame (which is completely dark except for the motion of the plates and lights of the car going by) to reliably trigger a recording. If you can increase your motion detection sensitivity in nighttime mode independent of daytime mode, that may help.
However, in my opinion you are making a mistake trying to do LPR with cameras operating in motion detection mode. My advice is to record 24/7. Digital storage is cheap, and bandwidth is not an issue with H.264 compression.
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I will probably end up doing this. But I would still like a trigger event to work. Makes it easier to scan the cars when looking. I'll dial up the sensitivity even more tonight.
- Nov 25, 2016
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In that case, I'd recommend doing the following:
(1) Use 24/7 recording for your main LPR video feeds.
(2) Set up each LPR camera profile so that at night it also saves a JPEG image whenever motion is detected. All you have to do then is scan through the JPEG images, or just look at the time stamps to see when the camera was triggered, and then go look at the video recording.
I use that trick with my SD49225T-HN to monitor my parked car at night. Each morning I quickly scan through the thumbnails of the motion-triggered JPEGs captured by the camera. If I see a person standing or walking next to my car, I then look at the video feed to see if they tried messing with my vehicle.
That's awesome! Didn't even think of that for any of my cams. Gonna have to set that up.
I'm having the focus shift issue now though when switching to night on the Z12 (using day/night profile). Reading back through the thread to see my options....
- Nov 25, 2016
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You can try the reflective tape trick to maintain focus, or keep the cameras in the same B/W profile both day and night.
OK I thought I read something about a reflector. I was considering purchasing a reflective road marker to stick in the middle of the road where it's focused.
I'm still reading but I thought @bigredfish mentioned keeping the IR on for a day/night setting helped also? Or is it just a single B/W setting that does it? Thanks!!
Darren
Also have the cameras switch from Color to B/W before Sunset / Sunrise etc, that has worked for me and I also believe that @bigredfish also has had some good luck with that. Usually setting it to switch 45 mins or so before seems to work.
Also have the cameras switch from Color to B/W before Sunset / Sunrise etc, that has worked for me and I also believe that @bigredfish also has had some good luck with that. Usually setting it to switch 45 mins or so before seems to work.
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bigredfish
Known around here
I have two of the Z12's, both capturing at 120ft.
On one we keep it in B&W 24/7 and have had no focus issues.
On the other I have it in color in the daytime, B&W at night using the "Schedule" profile. The trick it to have the camera switch to B&W 45min-1 hour prior to sunset, and wait until one hour after sunrise to switch back to color. The morning setting is hit and miss for about 30 minutes, the evening switch works fine because the IR is on and even though some twilight, am able to capture just fine. The amount of capture time you will lose will be highly dependent on the location of the sun to your camera. This one faces due East, so its a bit of a problem early morning for about 30 minutes before the switch.
On one we keep it in B&W 24/7 and have had no focus issues.
On the other I have it in color in the daytime, B&W at night using the "Schedule" profile. The trick it to have the camera switch to B&W 45min-1 hour prior to sunset, and wait until one hour after sunrise to switch back to color. The morning setting is hit and miss for about 30 minutes, the evening switch works fine because the IR is on and even though some twilight, am able to capture just fine. The amount of capture time you will lose will be highly dependent on the location of the sun to your camera. This one faces due East, so its a bit of a problem early morning for about 30 minutes before the switch.
tech101
Known around here
I dont get much bikes on the street but still time to time I do get them. How do you guys deal with them ? I mean I have it zoom out at daytime to a point where I can get some what general description of the vehicle in the frame as well. With bikes I guess it needs to be zoomed in a bit further.. to get those plates.
I've got it set to switch 45 min before sunset for tonight (7pm PST) the switch from night to day has no problem so far for the past 2 nights. The other thing I can't figure out is I'm only at 88ft so I thought this was only supposed to happen at longer distances? If this works out ok I might try and move the zoom further out to our intersection (about 180-190ft)
Thanks @Wildcat_1, @bigredfish and @wtimothyholman That did the trick. Here is the 7pm switch and still going strong later:
7pm
8pm
7pm
8pm
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bigredfish
Known around here
I find it takes two cameras to get the best tag reads. LPR cam zoomed to about 1-2 car widths, and an overview camera to see everything else.
Your shots look very good, but I think you'll have better consistency with a tighter zoom.
...And cut that branch
Your shots look very good, but I think you'll have better consistency with a tighter zoom.
...And cut that branch
Parley
Known around here
This appears to be the LPR thread for the Dahua IPC-HFW5231E-Z12E which I will be ordering from Andy. I have no problem getting license plate numbers during the day. It is the night time where my problem lies. Bottom line is I do not need color and looking through the thread I can go black and white for both day and night and maybe save a problem or two.
Looks like 1/2000 shutter speed is about right. I will follow the settings that bigredfish has come up with. Here are 3 cameras looking at the current streets I want to cover and the angle will be pretty much the same. These are looking West, North and East repectively. The North and East angle will be slightly better with the new LPR cameras. Any comments welcome.
Looks like 1/2000 shutter speed is about right. I will follow the settings that bigredfish has come up with. Here are 3 cameras looking at the current streets I want to cover and the angle will be pretty much the same. These are looking West, North and East repectively. The North and East angle will be slightly better with the new LPR cameras. Any comments welcome.
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bigredfish
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I think you'll be fine @Parley
My settings will get you in the ballpark, but ambient light conditions will vary from location to location so you may need to tweek some. My one Z12 capture in a very dark spot, the other has help from a nearby street light.
Getting enough IR on the plate is important obviously.
My settings will get you in the ballpark, but ambient light conditions will vary from location to location so you may need to tweek some. My one Z12 capture in a very dark spot, the other has help from a nearby street light.
Getting enough IR on the plate is important obviously.