what are the benefits of focal length in a ip camera

[ace2]

Looking at foscam cams and comparing the difference between the FI9804W & FI9805W.

one has a focal length of f: 2.8mm and the other has a focal length of f:4mm, both have a 70° view angle..

Not too fussed about display resolution as i'll be reducing it a bit. It's only going to be used for a weather cam..

[ace2]

This is where i will be installing the ip camera, it's beside the weather station...


sorry it's a screen shot of a video from mobile phone, but give you an idea of what the camera will need to capture....

[tumutbound]

Do you mean focal ratio? That would be F2.8 or F4 without the mm.
The smaller the F number, the more light enters the lens.
It will depend on the sensor in the camera as to whether the difference is really noticeable.

Most (all?) of these types of cameras have a fixed focus of from maybe 500mm to infinity.

EDIT; Read you original post PROPERLY

A F=4mm lens would be more powerful i.e. things will be closer, than the F=2.8mm lens. It will affect the field of view in that the F=4mm lens will have a narrower view that the F=2.8mm will.

If it's of any use, the camera used for my webcam has the following specs:
Sensor size: 3.67 x 2.74 mm
Pixel Count: 2592 x 1944
Pixel Size: 1.4 x 1.4 um
Lens: f=3.6 mm, f/2.9
Angle of View: 54 x 41 degrees
Field of View: 2.0 x 1.33 m at 2 m
Full-frame SLR lens equivalent: 35 mm
Fixed Focus: 1 m to infinity

[ace2]

so I should pay the extra and get the f4 one!!!!

[tumutbound]

so I should pay the extra and get the f4 one!!!!

Not unless there's a feature you want to make stand out from the sample scene you gave i.e. 'zoom' in on it.
A wider view is what you want for a weather camera.

[ace2]

like to have a closer view of hills maybe..

these are the 2 camera's i'm looking at:

http://www.foscamaustralia.com.au/All-F ... r-Warranty


http://www.foscamaustralia.com.au/All-F ... uct_id=123


they seem pretty similar in features, one is a 1mp and the other 1.3, but I don't think I need that type of res due to my web space max

[tumutbound]

If it helps in web space calculations, my webcam images are 1280x768 and are 364K in size.

[hills]

like to have a closer view of hills maybe..

I beg your pardon?!?

[ace2]

like to have a closer view of hills maybe..

I beg your pardon?!?

You never know what i might see!!!!

[ace2]

If it helps in web space calculations, my webcam images are 1280x768 and are 364K in size.

more concerned with creating time lapse videos, hence why a low res camera will do...

took the res down to 640 * 480 to test and made a 11.4MB video for about 7 hours, which take a photo every 30 seconds.

calculate at a higher res(1280 * 768) and you're looking at too many MB's!!!

[hills]

like to have a closer view of hills maybe..

I beg your pardon?!?

You never know what i might see!!!!

Hahaha!! I agree with tumutbound that you would want to see as much of the sky as possible especially if you're going to make a time lapse video from the images. If you take a look at my webcam you can replay the last 24 hours, but as I'm at 500m I'm quite close to the clouds and you don't get that smooth look of the clouds moving across the sky. I think if you focus in on the hills you'll get this same effect. That said my images are taken every 5 minutes and not every 30 seconds so that doesn't help either.

[ace2]

So i should be leaning towards this one :

focal length f: 2.8mm
Aperture F2.4
Angle of View 70°

which will give a better coverage of the clouds and not this one :

focal length f:4mm
Aperture F2.4
Angle of View 70°

is that what i'm under standing???

[tumutbound]

Go for the F=2.8mm as it will give a (slightly) wider shot that the F=4mm.
A web search for 'focal length differences' will bring up some images which will demonstrate the difference that focal lengths make on the captured image, nothing for the size lens you're looking at. Try the demo from Canon (noisy!) or Tamron

[AllyCat]

Hi,

But you say that they both have the same Angle of View (70 degrees) so the image will (should) look the same. That's unless the image has a different Aspect Ratio, e.g. 16:9 ("Widescreen") compared with the normal 4:3.

If the lenses have different focal lengths (with the same field of view), then that implies that the Image Sensor is a different size. That may be because it has more pixels or because the pixels are larger. Larger pixels are advantageous because they can collect more light (photons), so give a less noisy image in very low light conditions.

A lower "f-number" is generally better (it collects more light) but f2.4 is only marginally better than f2.8. However, a lower f number (and also a longer focal length) gives less Depth of Field, not critical for Landscapes, except that the focus may need to adjusted more accurately.

Generally a larger sensor (associated with a longer focal length for a given viewing angle) is preferable, either to give more pixels (thus higher resolution or detail) or higher sensitivity. But all those numbers only tell part of the story, the final result will depend as much on the overall quality of the lens and/or the image sensor.

Cheers, Alan.

[vaggos]

This is the view of FI9805W as i bought it without any changes: But this cam dont update my page with her own ftp. You must use a programm like yaw cam or tin cam to ftp it. Also the image at dark isnt so good. But during the day, is perfect.
Regards
EDIT: I dont use anymore tin cam. I prefer a script. But after the two last updates the view at night isnt so good. There is a lot of noice in the left side.