superpatpat
Getting the hang of it
Hello everyone, I still have 2 cameras to buy to finish my kit dahua and I'm not sure if I should take 2.8 or 3.6 the camera should be 20 feet from the subject and cover 20 feet wide so I'm waiting for your advice
2.8 vs 3.6
- Thread starter superpatpat
- Start date
Take a look at this chart - to identify someone with the 2.8mm lens that is popular, someone would have to be within 13 feet of the camera, but realistically within 10 feet after you dial it in to your settings.
I would go with 3.6mm
I would go with 3.6mm
superpatpat
Getting the hang of it
merci
IAmATeaf
Known around here
Difficult to say without a pic of the area to be honest.
These are screenshot of 5442-ase 3.6mm mounted in my driveway
These are screenshot of 5442-ase 3.6mm mounted in my driveway
superpatpat
Getting the hang of it
thank you very much for the info
glenwood
n3wb
Was just comparing the two yesterday.
2.8mm and 3.6mm from same mount location:
2.8mm and 3.6mm from same mount location:
mat200
IPCT Contributor
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Hi @superpatpat
Many of us feel the Dahua DORI measurements are overly generous ( making the DORI distances too long ), do check out the DORI section of the cliff notes.
In general I only like 2.8mm lens when the suspect will be close to the camera, and want 3.6mm or stronger for further away
A popular starlight model a few years back were based on a 2MP sensor, which for 100ppf ID distance from the DORI calculations came to:
Dahua IPC-HDW4231EM-AS starlight fixed lens 1080p 1920x1080 ( 2MP )
- w/2.8mm lens FOV H 110 degrees: 10 feet { area covered 95.94 sq feet covered }
- w/3.6mm lens FOV H 87 degrees: 12.65 feet { 121.43 sq feet covered }
- w/6mm lens FOV H 51 degrees: 21.58 feet { 207.16 sq feet covered }
or
w/2.8mm FOV H 110 : 20 feet
w/3.6mm FOV H 87: 25.3 feet
( this is assuming effective pixels, low light image capture will reduce the effectiveness, as will compression, fog, rain, glare, bright light, shade / bright in the same frame .. )
Last edited:
bigredfish
Known around here
3.6mm
superpatpat
Getting the hang of it
as we say a photo is worth 1000 words, the red arrow will be the position of the camera and the blue arrow is the finish of my land because it has a neighbor who remains there. I would like the camera to go no further that the white fence in my opinion 3.6 will be better than 2.8
better than 2.8
better than 2.8
Hard to tell from that angle, but it looks like the pergola is going to take up a large amount of the field of view and at that distance if it is running B/W with IR there could be some IR bounceback.
Do you plan to turn it to look straight towards your house or more towards the fence?
Do you plan to turn it to look straight towards your house or more towards the fence?
superpatpat
Getting the hang of it
I want to look at the stairs leading up to the porch and the garage door
IAmATeaf
Known around here
Post a pic of the actual view, difficult to imagine what we can’t see?
superpatpat
Getting the hang of it
This is the real view, the camera will be below the soffit or the red arrow, I want to see the staircase leading to the patio, and the door on the right is in the rear garage, must not protrude too far to the right because I'm going to see the neighbor's patio
superpatpat
Getting the hang of it
ah sorry your good reason, i am going to take a picture
superpatpat
Getting the hang of it
here is the picture, it is about the angle that I would like, because the wider I will see the neighbor, 3.6 should be correct when do you think?
IAmATeaf
Known around here
I think with a 3.6mm you might struggle to get anything except maybe the last 2 steps of the stairs and the 2.8mm might be too wide? Best option would be to get the vari which would allow you to dial in the view and zoom exactly as you require.
user8963
Known around here
are u sure that its 3.6mm ?? are the cameras mounted high(around 5m?) ? i have a similiar situation and mounted a 3.6mm in around 2,5m and i am getting not that angle... its really hard to tell because the cars look more curved but it could be a bias because of the rounding of the street...
IAmATeaf
Known around here
Def 3.6mm, one is mounted at around 8ft and the other around 10ft.
user8963
Known around here
wonder what would 2,8mm looks like at the same position...
if you compare to posted pictures from glenwood, ... hard to tell its 3,6mm for me
maybe that is the problem with sample pictures... any situation is complete different. no one knows the dimensions of the objects etc.