ALPR: anyone have a 100mm lens they like?

As a side note, either my settings are wrong, or the designers of the camera haven't used it much with a lens this long. During the day, when a car occupies nearly the entire frame, it is not detected as an object, so the "line crossing" feature is not triggered with larger vehicles. It works at night because you see only the lights and the plate which are much smaller light areas in an otherwise dark image.
 
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object detection requires the object to be smaller than the frame and for it to have room on either side to detect it.. it wont work when tightly zoomed as it does not have adequate time to detect the object before it crosses the line.

amazing difference; now you got me thinking about upgrading my 60mm
 
The lens works fine without auto-iris. I guess most security cams except for box-cams have fixed iris. The camera compensates the exposure by using a shorter exposure time during the day. It is true, wIth most lenses you only get the best resolution somewhat stopped down, but as you can see, this lens does pretty well wide open.
 
Question. That focus difference for day and night is that done with the function Dahua describes as ABF ?
edit: I guess yes as I found this post by nayr: Dedicated License Plate Cam project

And the need for the focus to be different for day and night is that retro reflective of the license plate than I assume..

Looked it up and it is returning the light back in the direction it came from. So that is than directly the reason the ir cannon must be very close to the lens, as the light is returned there.
 
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FYI, in case anyone else wants to do something similar. I wanted to try a lens with manual adjustable iris, so I got a used Nikon f/2.8 100mm Series E lens, plus Nikon F mount to C adaptor. This works pretty much as well as the Canon lens, at lower cost. I ended up leaving it open (at f/2.8) because I get wicked diffraction spikes on headlights at night from the iris blades. If you only wanted it during the day, you could stop it down for better depth of field.
 
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I am about to tackle this project again now that there have been reports on Nextdoor of kids throwing eggs at houses/cars in the neighborhood. I previously attempted this project using a Hikvision bullet, but had problems getting a clean JPEG file from the H264 stream (the camera did not support MJPEG at high resolutions). This time I'm likely to go with the camera that Nayr used, but am open to other Dahua options based on my setup.

I am planning on mounting the camera towards the street as indicated on the map. I am hoping that with this setup I would be able to catch cars coming down the court as well as those that turn left from the side street. I am thinking I would not need that much zoom given the cameras proximity to the street. Would I be able to get by with a simple bullet camera with a 6mm lens from this distance? I am sure a box camera with a 10-60mm lens would work, but wondering if that would be overkill.
 

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Thanks, Nayr! According to the tool I will need at least a 14mm lens at a distance of 44'. Looks like the box camera will be the best option. Would you recommend the same IR illuminator that you used, or could I get by with a less powerful one?
 
This makes me frustrated with AZs lack of required plates in front and back of the vehicles... I need 2 setups for my road since they are rear only required. :(
 
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Its hard to power that illuminator and the camera off the same line due to how much power it draws, you should be able to get by with a less powerfull version in theory.. Ive got the 10W, I believe there are 8W and 6W versions that are also adjustable focus for a cheaper price.

if its too much light you can always adjust the focus on the illuminator so its wider and less focused; thats one of the nice things about that illuminator.. I think the 8W version would be much easier to run off a 12v PoE splitter.. After toasting a few splitters in the birdhouse, I ran a 2nd ethernet cable and put the splitter in my basement powering just the illuminator.. think it was a combination of heat buildup and high load that was killing em, the external splitter in my basement has been running for months and through all summer w/out failure.. the internal birdhouse splitter barely lasted a month before quitting on me and I was measuring temps inside as high as 140F, now I rarely measured it above 100F in the summer w/the IR on.
 
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wantafastz28 said:
This makes me with AZ required plates in front and back of the vehicles... I need 2 setups for my road since they are rear only required. :(
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In my state both front and back plates are required, but that is seldom enforced based on what I see. Most new cars here have no plates at all (allowed for 90 days after sale, until a new law takes effect in 2019). Plus some plates are dirty or otherwise unreadable. I'd say it's a good idea in every case to have cameras facing both ways.
 
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cam235 said:
In my state both front and back plates are required, but that is seldom enforced based on what I see. Most new cars here have no plates at all (allowed for 90 days after sale, until a new law takes effect in 2019). Plus some plates are dirty or otherwise unreadable. I'd say it's a good idea in every case to have cameras facing both ways.
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Agreed. All it does is postpone it for me. In all honesty I probably don't need any of this, being in a nice neighborhood... luck favors the prepared and it has been a fun project for me so far. When some extra money falls in my lap, I will dabble.
 
BTW, here's an example using the Dahua 4MP box cam with Nikon manual 100mm lens +C-mount adaptor. The lens is wide open at f/2.8 and this van is about 250 feet from the camera. The white "STOP" pavement marking is 330 feet away. Right now I record only 1280x720 resolution to reduce backend processor load; the image is still good enough. I'm in a nice neighborhood also but... seems burglars decided that folks here might have nice stuff.

OnTrac_2017-01-04_14.41.21_356_359.jpg
 
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looks great, you achieved a nice focal depth with that setup and distance.. good work.

got a pic of the camera w/the lens mounted? wonder if it'll fit in my birdhouse
 
I'll try to get a picture when it's daylight. Without the optional lens hood, the camera + adaptor + lens is about 8.5 inches long. The front filter thread is 52mm. The Nikon is somewhat smaller than the Canon lens I was using before. If your range is only 150 feet, the field of view of the 100mm may be too tight unless your cars always stay centered in the lane. The Nikon E-Series also has a 50mm lens, about the same size but f/1.8 instead of the 100mm f/2.8 that I got.

Nikon Series E 50mm:
http://www.mir.com.my/rb/photograph...ieslenses/images/Series_E_50mmf18s_MKII_A.jpg

100mm: http://www.mir.com.my/rb/photograph...serieslenses/images/MISA_SeriesE100f28s_C.jpg
 
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cam235 said:
BTW, here's an example using the Dahua 4MP box cam with Nikon manual 100mm lens +C-mount adaptor. The lens is wide open at f/2.8 and this van is about 250 feet from the camera. The white "STOP" pavement marking is 330 feet away. Right now I record only 1280x720 resolution to reduce backend processor load; the image is still good enough. I'm in a nice neighborhood also but... seems burglars decided that folks here might have nice stuff.

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Don't fall into the trap of thinking crime is less likely to happen in "nice neighborhoods".

Great job on the plate cam!
 
looney2ns said:
Don't fall into the trap of thinking crime is less likely to happen in "nice neighborhoods".
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I term from someone who broke into my truck and got caught years ago... "You don't shit where you eat." They don't steal in their own neighborhood.
 
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