Troubleshooting LPR

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blazin912

Getting the hang of it
Sep 15, 2019
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MA
I'm using an HFW5241, for a while I've had this working quite well during the day but couldn't get it working well at night.

I'm not there yet; however, in my hunt I found notes that these cameras have focus shift issues at > 85% zoom. Also switching color <-> BW can cause this issue.

I'm running the Sunrise/Sunset utility to drive zoom/focus but I'm not sure if that cures the focus shift, ie the shift is consistent when you shift between color/bw, or if I should keep my zoom less than 85% and use B&W all the time.

While that question is open, I'm debugging my placement/B&W settings and I've turned my day plates into full ghost plates:


LWfcWVd.png


This would seem to indicate an extremely high level of red light? Our plates are red raised letters. What setting could I have messed up?
 
During the day, switch it to B/w and get he focus number and then put that into the utility.

Do not let the camera try to focus it, that is whole intent of that utility is so that we can force a focus number.

And your shutter is way too fast or that isn't a shot from the night.

Unless you have stadium quality light, all you will see is the head/tail lights an plates.

You need to run a 1/2000 shutter and this camera only does LPR and not an overview also.
 
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Thanks for your input, I've been following your comments else where. You're right that's not a night shot, it's day but look at the plate.. wtf is going on there?

I should also ask, does this mean I can use at 100% zoom? As long as I figure out the focus shift and force the focus properly with the utility?
 
What shutter speed was that at?

It almost looks like it is a plate with printed on letters or a paper plate or a plate with anti-something on it.

It also looks like brightness and contrast are too close together, which will make those kind of plates difficult to read properly.

The zoom issue was more with the 5231 model than the 5241 model. I am running mine at 100% zoom without a problem. It is just a matter of getting the focus and zoom numbers down.

Make sure when you manually focus that you move the step down to 1 and not do it on the default 20 step.

But at that tight of a zoom it is even more critical that you have someone stop a plate in the center of the image and you manually focus it to that point.
 
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wittaj said:
What shutter speed was that at?

It almost looks like it is a plate with printed on letters or a paper plate or a plate with anti-something on it.

It also looks like brightness and contrast are too close together, which will make those kind of plates difficult to read properly.

The zoom issue was more with the 5231 model than the 5241 model. I am running mine at 100% zoom without a problem. It is just a matter of getting the focus and zoom numbers down.

Make sure when you manually focus that you move the step down to 1 and not do it on the default 20 step.

But at that tight of a zoom it is even more critical that you have someone stop a plate in the center of the image and you manually focus it to that point.
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That was 1/1000 I know the car and it is standard metal with white background, red raised text.

Now that I understand the focus issue can be resolved by manual forcing, I'm abandoning daytime b&w which seems to be the cause. It concerns me though because if there is some other filter that blocks the red channel, then I won't be able to see the plates at night in B&w


Fyi my 5241 still has a shift in focus when you switch between color/b&w clearly the optics change when you do that.
 
OK - some plates running B/W in daytime are problematic. I went to color during the day for that very reason.

At night it will not be an issue because your image above was dealing with daytime light. At night, you will only have the reflective IR bounce off the plate, so it should be better.

The focus is different between color and B/W/IR as those are different light spectrums so you should see it shift.

Here is a great older post that goes into detail how the focus for daytime and nighttime can be different because of IR. For some they are the same, but for a lot of people, it is different:

Infrared focus shift - explanation
 
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wittaj said:
OK - some plates running B/W in daytime are problematic. I went to color during the day for that very reason.

At night it will not be an issue because your image above was dealing with daytime light. At night, you will only have the reflective IR bounce off the plate, so it should be better.

The focus is different between color and B/W/IR as those are different light spectrums so you should see it shift.

Here is a great older post that goes into detail how the focus for daytime and nighttime can be different because of IR. For some they are the same, but for a lot of people, it is different:

Infrared focus shift - explanation
Click to expand...
Ok gotcha.. alright I need to reposition again and dial in the night settings for sure. There is very little light on the street so I may need an external IR to get it to hit the plates effectively from 130ish feet
 
@wittaj Any thoughts on this:


Mm2UGOf.png


That is my car stationary, I went out to tweak my settings. Couldn't log into the camera from that location, poor cell coverage :( so I couldn't make updates. My IR is full 100% but my plate is blacker than black.

I assume that would be running 1/333 since I've let my exposure go as high as 3 ms. Any thoughts on where to go from there? FYI it's dark here, very dark. We have 1 street light in front of my house at the end of a cul-de-sac but my LPR is pointed down the street away from this light to catch cars coming head on. More gain? HLC?
 
That is a great clear picture, except no plate LOL.

I would question if the IR is on? Do you see the red when looking directly at it? There should be some reflective glare off that plate. It looks like a plate isn't there.

Do not do a range for the shutter or gain because then the camera will adjust it and once it does, it can start screwing with the focus then as well.

I have seen the newer Z12 is on a different chipset and needs higher gain.

So try a shutter of 1/1,000 and gain of 70-70 to start and let's see what the image looks like and then we go from there.

Here is a representative sample of plates I get at night of vehicles traveling about 45MPH at 175 feet from my Z12E and we have no streetlights and nobody has outside lights on - this is all IR from the camera:

1635894036181.png
 
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wittaj said:
That is a great clear picture, except no plate LOL.

I would question if the IR is on? Do you see the red when looking directly at it? There should be some reflective glare off that plate. It looks like a plate isn't there.

Do not do a range for the shutter or gain because then the camera will adjust it and once it does, it can start screwing with the focus then as well.

I have seen the newer Z12 is on a different chipset and needs higher gain.

So try a shutter of 1/1,000 and gain of 70-70 to start and let's see what the image looks like and then we go from there.

Here is a representative sample of plates I get at night of vehicles traveling about 45MPH at 175 feet from my Z12E and we have no streetlights and nobody has outside lights on - this is all IR from the camera:

View attachment 107021
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Ok let me fix at 1/1000 and up the gain. The red dots are definitely visible on the face of the camera that's for sure.. did you mean 70-100 for gain?
 
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No, do not use a range - since we cannot set one number, just do 70-70. And then see what happens. My newer Z12 I have to run 80 gain, but my original Z12 is down at 40ish.
 
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@wittaj couldn't get out there last night, but again I'm having issues with B+W mode.

Is it possible there is some filter issue on my camera?

This is the new night mode settings at nearly 8a, so much more ambient but again the license plate is white. It's like the BW filter is using a strong red filter. Great, plates here use red text... thoughts?


gHGlYwH.png
 
Were you able to get any plates at night or did nobody drive by LOL?

These cameras will struggle two times a day - around dusk and dawn. You can try keeping it in night mode a little longer or end it earlier and see which is better.

That is a tough angle so the IR is hitting at more of an angle so it could wash it out, especially with the red in the plates.

Any chance you can improve the angle to get a more straight on shot?
 
wittaj said:
Were you able to get any plates at night or did nobody drive by LOL?

These cameras will struggle two times a day - around dusk and dawn. You can try keeping it in night mode a little longer or end it earlier and see which is better.

That is a tough angle so the IR is hitting at more of an angle so it could wash it out, especially with the red in the plates.

Any chance you can improve the angle to get a more straight on shot?
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Well, I've got two issues haha, my night triggering hasn't been excellent and not many drive by at night as we're one of a few houses at the end of cul-de-sac. Day traffic? yes

As for getting a more straight angle, unfortunately I don't have a great way. At one point in time I was able to "thread the needle" as drawn below, but the trees have grown in and now that is not an option.

Trees are outlined in red, the growth issue is the not only the one closest to the house but also the one closest to the street. Cutting down that tree is not an option haha..


h8M4269.png
 
Yeah night triggering is hard. Cannot use IVS and the zoom is so tight that the camera motion makes it tough.

Are you using BI? I have had good success with motion detection, but I also record 24/7 just in case.

How about putting that camera on the tree! Many here have done that.
 
wittaj said:
Yeah night triggering is hard. Cannot use IVS and the zoom is so tight that the camera motion makes it tough.

Are you using BI? I have had good success with motion detection, but I also record 24/7 just in case.

How about putting that camera on the tree! Many here have done that.
Click to expand...

Yes I use BI I'm recording 24/7 on everything else, maybe I'll setup to record continuously at night and see what comes back.

Unfortunately It's not my tree :( Maybe I could trench over to the big pile of trees instead. That might be a bit intrusive as the FOV would shoot over the end of my neighbor's driveway and be basically on the property line. Right now my camera is tucked away a bit and noticeable from the street, putting it up on a tree where the neighbors see it might be frowned upon.
 
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That is what some brown paint is for LOL.

Many here have hid it pretty well in a tree.

Or could you take it lower and put it in a decorative box and shoot under the tree?

@samplenhold and @IReallyLikePizza2 have examples doing the box and the tree.
 
Maybe I'll give that a shot, I just did a quick survey and looks like I could hide a box near the base of the trees easily. I've got access to do a home run from that side pretty well too. Step 1, I'm taking my plate off my car tonight to see if the IR does anything useful with the plate pointed directly at my camera. If the camera has the a flaw with Red text.. guess what will be up for sale? haha
 
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