Dahua HFW-1831E in-depth review

fenderman

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The specs for the 2831T-zs Lite 1.0 do NOT show the cam as being Starlight+ but the Lite 2.0 SHOWS it as being Starlight + so the question remains DID Dahua add the algorithms to make it a Starlight+ in Lite series 2.0 OR is it a Starlight+ in Lite 1.0 The lens is the same.
You are assuming there is an actual performance difference between the two...stop eating up the marketing. Personally I would hold out until Super Starlight 5.0+++ Ultra+++ is available.
"algorithms" wont help night performance one bit.
 

molarbear

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I've been considering getting a few HDW4231EM-ASE for a business premises - I know I'm comparing a 2mp camera with an 8mp camera but hear me out - seeing as the HFW-1831E's seems to be essentially as good as the Starlight sensors at night (from what I can see with the photos above) and much better during the day, is there a reason not to get these and if I only want to 2 megapixels to knock down the stream to 2mp, and if I'm ok with 8 mp to leave it at that? I initially only thought I'd need 2 megapixels but wouldn't complain if I had more.

A microphone is not a feature I'd need.

It's a business premises so aesthetics aren't especially important. Connected to a NVR so lack of SD card isn't a huge problem. I'd be running around 12 cameras so with 8tb of storage NVR I would think that most would only run 2-4mp so I don't run out of storage too quickly, with the odd camera at 8mp if required.

Thoughts? Good idea? Bad idea? Cheers!
 

fenderman

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I've been considering getting a few HDW4231EM-ASE for a business premises - I know I'm comparing a 2mp camera with an 8mp camera but hear me out - seeing as the HFW-1831E's seems to be essentially as good as the Starlight sensors at night (from what I can see with the photos above) and much better during the day, is there a reason not to get these and if I only want to 2 megapixels to knock down the stream to 2mp, and if I'm ok with 8 mp to leave it at that? I initially only thought I'd need 2 megapixels but wouldn't complain if I had more.

A microphone is not a feature I'd need.

It's a business premises so aesthetics aren't especially important. Connected to a NVR so lack of SD card isn't a huge problem. I'd be running around 12 cameras so with 8tb of storage NVR I would think that most would only run 2-4mp so I don't run out of storage too quickly, with the odd camera at 8mp if required.

Thoughts? Good idea? Bad idea? Cheers!
The starlight is significantly better in low light, but the 8mp is good. The 2831 has the sd card slot + varifolcal.
The resolution has no impact on storage space, only the bitrate matters.
 

ProsjektX

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With the positive reviews of this camera, the related dome version HDBW-1831R, which seems to use the same sensor, is almost nowhere to be found for purchase. How come?
 

Geitje

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So I use this camera for some months now, I'm quite satisfied with it, be it only for only: the ghosting of moving objects in low light is really annoying. I read it should be less when the bitrate is higher. However: Dahua for some reason limited the bitrate to 10K after the first firmware version. Why? And: when will bitrate cap be cancelled. This camera is capable of so much better images, however, the bitrate cap limits us so much! Hope Dahua reads this and will come with a version with much higher bitrate.
 

carteriii

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the ghosting of moving objects in low light is really annoying. I read it should be less when the bitrate is higher.
Ghosting has nothing to do with bitrate. Ghosting is really just blur which is a result of a slow shutter speed. The "ghost" image you're seeing is not the result of capturing fewer pixels (bitrate). It's because the object in motion has moved from one place to another faster than the shutter could "freeze" the motion. The "ghosting" is because your object was there a fraction of a second ago, but has moved on while the shutter was still capturing the image, so you're seeing both the object and the background in the same pixel(s). Try manually adjusting your shutter speed to be faster. That has other consequences (darker image in low-light situations), but it can address the ghosting/blur.
 

Geitje

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Ghosting has nothing to do with bitrate...
Thanks for your reply. I understand It relates to light exposure to the lens and not much to bitrate. Wil a lower FPS then also decrease the ghosting of moving objects? I read here the 3D noise reduction also involves the ghosting?

Anyhow: the bitrate remains an issue with moving objects: this camera can do FPS 30 in 4K, image quality would be lot better in higher bitrates. See also first post in current topic, blocky artifacts appear on moving objects when using lower bitrates. Why not give the user the option of higher bitrates, when the camera is capable? We know it kan handle at least 15K bitrate.
 

carteriii

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I understand It relates to light exposure to the lens and not much to bitrate. Wil a lower FPS then also decrease the ghosting of moving objects?

Anyhow: the bitrate remains an issue with moving objects:. . .
No, a lower FPS will not help. If you cannot get a fast enough shutter speed to eliminate the ghosting or "motion blur", then changing FPS will simple give you more or fewer blurry images.

You say you "understand it relates to light exposure", but then you ask whether FPS will change and then say, "the bitrate remains an issue with moving objects." It doesn't sound like you really do understand the difference so let me try again.

Bitrate doesn't help motion blur. Bitrate is more a control over the overall quality of whatever the lens sees AFTER the image has been captured through the lens. Think of it like compression on a jpeg image. When you lower the overall quality (through bitrate or jpeg compression), that loss of quality is different than motion blur/ghosting. You definitely want a high enough bitrate for a quality image, but bitrate cannot fix an image which is bad to begin with due to a slow shutter speed that results in motion blur.
 
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Geitje

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You say you "understand it relates to light exposure", but then you ask whether FPS will change and then say, "the bitrate remains an issue with moving objects." It doesn't sound like you really do understand the difference so let me try again.
Thanks for your reply and explanation, but I understood correctly I think:). My question regarding FPS comes indeed from shutter speed in photography, where longer exposure time gives a brighter and sharper image. However I did not count for motion which also continues during the longer exposure times (as you point out), and could even result in more blur.

What I mean when relating bitrate to motion picture quality is best explained by quoting from the first post of this thread:
It might sound strange, but the codec efficiency seems to be worse in comparison to 5831. In shadowed areas and on moving objects, blocky artifacts appear. Luckily Dahua has raised the top bitrate in 1831 to over 15mbit/s. At 25fps this is an equivalent for 9mbit/s @ 15fps in 5831. Before firmware update I had an option to set over 50mbit/s in custom mode. However at 30mbit/s I had lot of dropped frames even in live view. Over 40mbit/s there was no image, only black window. After rising the bitrate to 15000kbps the blocky shadows are much reduced but still present. Even 30mbit/s do not resolve the problem, while 5831R-ZE is almost free of such artifacts at 9mbit/s. See the below example.
This means picture quality of moving objects could improve if a higher bitrate is used. However I understand now that this is different from the ghosting which happens in low light conditions. I will barely make any diffence in that sense I see now.

Still, my request to be able to set higher bitrates for a camera which is able to deliver these is valid. It will make difference espacially in detailed images during day. I hope Dahua will make this possible again!
 
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