Sorry to ask again but I couldn't find the answer


Senior Member
How can I get an idea of what Field Of View a camera will have by using the lens length, like 3.6 mm F2.0 lens. What I'm familiar with is the X10 cams "Wide Eye" view and I would like to match up that FOV on a new camera. Make since? TIA

You guys answered this for me before but I couldn't find it with a search.
The field of view (FOV) is affected by the focal length of the lens (3.6mm in your example) and the size of the sensor (the CCD or CMOS element in the camera). For a given sensor, a shorter focal length will have a wider FOV. So, a 50mm lens will have a wider FOV than a 100mm lens.

Now, consider 2 different sensors and the same lens. If sensor A is smaller than Sensor B, then the same lens will give a smaller FOV on camera A than on camera B [1].

So, you can't compare focal lengths to get FOV without also knowing the sensor size.

The aperture (F2.0 in your example) does not affect FOV. It affects light gathering ability and depth of field (DOF). The aperture is the size of the light-gathering opening. A larger number (higher f-stop) is a smaller opening. The smaller the opening, the less light that gets in (and the darker the picture will be) but the greater the DOF. DOF is the amount of the image that appears to be in focus in front of and behind the actual focal plane.

Large aperture (small f-stop number, e.g. F2) = shallow DOF and bright image
Small aperture (large f-stop number, e.g. F11) = long DOF and dim image

So, the answer is that you need more information. For inexpensive cameras, it may be difficult to find the sensor size.

If you do a search online for "field of view" and "calculator", you will find many web pages that will compute field of view for a given lens focal length. However, most of them will be for film cameras. If you look for an astrophotography site, you will probably find one that allows you to enter the sensor size.

[1] This is something that digital SLR users worry about - since most sensors are smaller than 35mm film, the field of view of lenses decreases when you go from 35mm film to digital. This is also where the effective 35mm focal lengths that you see for point and shoot cameras come from. For a specific digital camera, a very short lens (a few mm) may be the equivalent of a 50mm lens on a 35mm camera (since the digitals have pretty small sensors).
Great explanation smee!! I've been looking for this type of info since I'm soon to be in the market for more cameras.

Rupp: If you do get that camera from Martin, let us know when you have it connected so we can see the quality.
Rupp, a friend just ordered this camera from Martin and is waiting for it to arrive. I'll let you know how it works when he gets it setup. I don't understand enough of the specs to see why this camera at $130 is not as good at the ones that are $200+. I guess we'll see.
I am sure it is as good, if not better. I am definitely looking forward to pictures as well, so I can compare it with mine.
I have this camera in my backyard, it is currently NOT connected to a screen capture device (long story) and is just viewed on my TV via the VCR so my wife can keep an eye on the kid when he is out there.

It does have a rather NARROW field of view, I do wish this was larger. I do like the day night performance and I'm happy with it considering the cost I paid.

Like I said, the only thing I wish was better was its field of view.

You guys have a short memory, this was the camera I had up and running for review during one of our Friday night chat sessions (a while ago). ;)