2.8mm or 4mm at these positions?

[JonasW]

We are looking at buying two new cameras to the house.

One recording the outside of the hen-house. Their yard outside is priority, the rest of the garden is a bonus.
Here I'm thinking 2.8mm to get the most vertical view close to the cam? The distance from the cameras position to the top of the netted yard is about 2-3 feet. The distance to the back of the house is about 55 feet.




The other camera will be recording the front door and driveway. Distance to the front door is 16-18 feet and to the far end of the driveway, about 50-55 feet.
View of the street isn't all that important, front door and driveway are the important areas. 4mm for this place?




The cameras I have in mind are two DS-2CD2365G1-I.

Any thoughts?

 

[looney2ns]

Please study this: Cliff Notes

 

[JonasW]

Please study this: Cliff Notes

Done. Can't say I found a answer to my questions?

 

[sebastiantombs]

There is no way to definitively determine what focal lengths you need from a couple of two dimensional photos. The smartest thing to do is to buy one varifocal camera and test each location to determine the correct focal length. I will say that the camera location on the front porch is probably too high for effective identification. Once you have the focal lengths established (converter is in the Wiki), use the varifocal as one of your cameras, but remember it is not a true zoom camera and is designed to be set to the needed focal length and left alone unless it is moved elsewhere with different requirements.

 

[JonasW]

I understand that, and that is why I wrote down the distance to different places in the picture. To get an idea of how big of a area I want to record.

I can't afford buying a varifocal camera of this quality so I'll have to take a chance with my guess of lens choice.

Thanks for the input.

 

[sebastiantombs]

A decent varifocal, Dahua 2231T-ZS is about $120USD and can save you wasting the money on two inappropriate cameras. We have a saying, do it right the first time, pay and cry once. Do it wrong, pay and cry twice.

 

[aristobrat]

Done. Can't say I found a answer to my questions?

The reference to IPVM Camera Calculator V3 might be helpful. Should let you pull up a Google Maps image of your house, position a camera around the exterior and see sample images. There's a little digital pin (person icon) you can move around and see how the image quality changes. It will also give you some numeric stats you can monitor as you move the person around. Keep an eye on the PPF stat, it's recommend that be 100+ at a location in order to ID someone that you don't know.

Also FWIW, the field of view angles vary a bit based on the image sensor. A 2.8mm lens on one model might be 15 degrees wider (or more narrow) than a 2.8mm lens on model that uses a different image sensor.

 

[JonasW]

Thought it would be good to post pictures of the finished install, to those who have similar questions.
Got exactly what I was after. Wide picture and close up on the hens because of the extremely close mount of the cam (2-3 feet).
And good enough picture to see identify someone at the door. Daytime I'm able to identify someone at the driveway too.

Here are pics from the NVR from the hens garden (2.8mm) and the front of the house (4mm).

 

[Ookie]

The main problem now is that 16:9 aspect ratio is pretty much being forced on us with the latest models.

A camera with a square (4:3) image would be ideal in the mounting location depicted by the second picture. You would have far more path at the bottom and road at the top.

Regrettably, the Chinese manufacturers have gravitated toward a format developed for entertainment. Not idea when you are looking down on a diagonal.

 

[aristobrat]

Isn't the aspect ratio a function of the image sensor's resolution, at least when running in full resolution? Some cameras will let you pick a lower resolution with a different aspect ratio but most folks don't seem to want to sacrifice pixels for any reason.

The cameras in this thread look like they a 6MP sensor that has a maximum 3072 × 2048 resolution... not exactly 16:9, but definitely wider than shorter when compared to 4:3.

I'd be curious to see what this camera looks like if it was rotated 90 physically (and with the firmware setting enabled to compensate for that). You'd see a lot more of the road/path, ... not sure how much of the horizontal scene would be lost, but there's some house siding in the scene currently that probably wouldn't' be missed tto much if gone.