libertybiberty
n3wb
Whats the advantage of either lens? And if one is so great, why have the other?
2.8 vs 3.6?
- Thread starter libertybiberty
- Start date
Every optical length serves a purpose.
The smaller the focal length, the wider the image, but the closer the object needs to be in order to IDENTIFY.
The larger the focal length, the narrower the image, but the object can be further away in order to IDENTIFY.
The 3.6mm will give a slightly more narrow field of view, but can IDENTIFY at a little further out distance than the 2.8mm.
And then we have varifocals that serve even greater distances.
The smaller the focal length, the wider the image, but the closer the object needs to be in order to IDENTIFY.
The larger the focal length, the narrower the image, but the object can be further away in order to IDENTIFY.
The 3.6mm will give a slightly more narrow field of view, but can IDENTIFY at a little further out distance than the 2.8mm.
And then we have varifocals that serve even greater distances.
mat200
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Looks like the tighter FOV on that one .. perhaps a 12mm lens
This one is more of a 2.8mm ..
libertybiberty
n3wb
Great answers! Gracias.
Damn, sweet Stoeger.
I'll give you $5.00 for it...
Damn, sweet Stoeger.
I'll give you $5.00 for it...
Broachoski
Getting comfortable
If the intruder is in my house, I will take that 2.8. If they start running outside then I will grab that 12mm.
libertybiberty
n3wb
I think I'd like one in 20ga. Easier on my hands when using both barrels.
But I digress.
Whats the MOA (field of view) of one of these cameras in 2.8?
4MP Starlight Turret IP Camera-IPC-T2431T-AS
But I digress.
Whats the MOA (field of view) of one of these cameras in 2.8?
4MP Starlight Turret IP Camera-IPC-T2431T-AS
mat200
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In general, when looking for the FOV search the data sheets of the cameras.
Once you have the FOV and resolution you can use the equation in the cliff notes to calculate the DORI ( I like 100 ppf spec vs the lessor one used by vendors .. )
libertybiberty
n3wb
Great info thanks, looking at data sheet now.
libertybiberty
n3wb
Those Cliff Notes are the bomb! Wow I have some reading to do....
libertybiberty
n3wb
Morning folks, heres one for you. DO these cameras have red LEDs or are they invisible in use? I can just see my house lit by red lights everywhere....
4MP Starlight Turret IP Camera-IPC-T2431T-AS
4MP Starlight Turret IP Camera-IPC-T2431T-AS
The cameras with infrared emit a tiny red glow when looking straight at them. Once you offset a little you do not see them.
The cameras that run at 940nm IR that does not emit the glow are not readily available and are more expensive.
Unless your house is completely dark, nobody will see them. A porch light or yard light will "light pollution" the ability to see the red IR.
The cameras that run at 940nm IR that does not emit the glow are not readily available and are more expensive.
Unless your house is completely dark, nobody will see them. A porch light or yard light will "light pollution" the ability to see the red IR.
The Automation Guy
Known around here
The IR emitters on that camera are in the visible range and appear as red LEDs. You won't see the IR light being cast out, but the emitter itself has a red glow.
I have both turret and bullet models of various Dahua cameras. I will say that the emitters on my turret cameras (there are two per camera) are very small and hardly noticeable. The emitters on the bullet cameras are larger and can be seen from the roadway and there are 4 per camera. That being said, they are still very small - the size of a single LED bulb. I see them, but I have to wonder if anyone else even notices them. I suspect not. Certainly none of my neighbors have ever ask or commented about them and we have friendly conversations quite often.
I have both turret and bullet models of various Dahua cameras. I will say that the emitters on my turret cameras (there are two per camera) are very small and hardly noticeable. The emitters on the bullet cameras are larger and can be seen from the roadway and there are 4 per camera. That being said, they are still very small - the size of a single LED bulb. I see them, but I have to wonder if anyone else even notices them. I suspect not. Certainly none of my neighbors have ever ask or commented about them and we have friendly conversations quite often.
libertybiberty
n3wb
Gooood, thanks!
SodFather09
Getting the hang of it
2 cameras for each location , 2.8mm for overview cameras , 4mm or 6mm mounted at 6 to 7 feet high for facial ID. Or better yet just get a motorized lens 2.8mm - 12mm and take the guess work out of it