Dahua IPC-HFW1831EP questions

I recently bought a Dahua IPC-HFW1831EP from Andy to replace an SV3C camera.

Overall I'm very happy with it, but I wonder if there's anything that can be done to make it better.

I attached day and night screen shots from it. The camera is mounted about 35 feet away from the subjects on the screen shots.

I was hoping for enough resolution to identify people at 35 feet at night.

Settings are as follows:

> H265, Smart Codec: Off, 3840 X 2160 res, 25 FPS, iframe 50, Variable bit rate, Quality: 6(Best), backlight mode: WDR (set at 50%), other settings all on Auto (WB, exposure, etc)

The camera has a 2.8mm lens.

Questions:

- Would a 4mm lens instead of 2.8mm make it better? (other lens suggestions?)

- Do I need a different camera? Recommendations?

- Can night time resolution be improved by changing settings?

- Is it unreasonable to expect night time identification capability at 35 feet without breaking the bank?


Thanks in advance for any advice. Shout-out to Andy for the excellent communications, quick reply to questions and fast shipping. I'll definitely be back.

A 3.6-4.0mm lens would help tremendously. Have a look in the WiKi, in the blue bar at the top of the page, and read the Cliff Notes in there. There is a section discussing facial recognition versus distance versus lens that will help you make a better choice. Another improvement would be more light at night or even switch to IR mode at night. From there it's playing with settings, testing and playing some more until you're happy with a night profile.

Typically, a 2.8mm lens is only good for an ID if the subject is within about 12ft. You still need adequate light.
You have motion blur in that shot at night, so, you can try this:
1-reduce the DNR as low as you can stand it.
2-Raise the frame rate to at least 1/60 or 1/120.
3-Change the cams view so that the lights on the house are not in the cams view, this is effecting exposure.
4-In the end, IR will do better.
But it will be tough with that lens and that distance.
Here is the calculator that @awsum140 mentioned, keep PPF>100
IPVM Camera Calculator V3

Thanks! @awsum140 do you know if it's possible to replace the lens on a Dahua camera without buying a new camera? I leave the lights on at night (LED bulbs) so the camera never switches to night mode. At the end of the driveway, most of the light is provided by the street lights and I can't really change that.

@looney2ns Thanks. I'll play with those settings. Same question for you: Do you know if changing lens is something that can be done without buying another camera? If so, any idea where I can source a 4mm lens?

You might also dial back WDR. It will brighten the picture, but tends to induce some motion blur in low light

Marcelor73 said:

I recently bought a Dahua IPC-HFW1831EP from Andy to replace an SV3C camera.

...

- Would a 4mm lens instead of 2.8mm make it better? (other lens suggestions?)

- Do I need a different camera? Recommendations?

- Can night time resolution be improved by changing settings?

- Is it unreasonable to expect night time identification capability at 35 feet without breaking the bank?


Thanks in advance for any advice. Shout-out to Andy for the excellent communications, quick reply to questions and fast shipping. I'll definitely be back.

Click to expand...

Hi @Marcelor73

Thanks, those are actually VERY good images from numerous samples I have seen.

A 8MP camera with a 90 degree FOV should give you about 25 feet to the 100 ppf point. The wider FOV camera you have should probably give you about 20 feet to the 100 ppf. This of course is theoretical - meaning good light, effective pixels.

If you want a consistent ID able image at the sidewalk range - look for a camera which has a tighter FOV, perhaps a varifocal, and good low light performance.

Marcelor73 said:

@looney2ns Thanks. I'll play with those settings. Same question for you: Do you know if changing lens is something that can be done without buying another camera? If so, any idea where I can source a 4mm lens?

Click to expand...

I have no experience in doing so with that cam.

In your night profile in Settings-> Exposure set Mode to manual then lower gain until IR turns on like maybe 0 - 50 or 60 from 0 - 90