[-Adrian]

Good examples are first person shooters, they're based on our beloved virtual cameras and i know from experience that if you go over ~90° a distortion becomes clearly visible and it starts to feel unnatural. So cameras probably do need such a low fov to come close to the impression of human vision. If you take a look at your eyes' fov you'll recognize that the angle in wich you perceive clear information isn't nearly as big as your memory suggests.

[Thomas An.]

Yes, I'm not sure. My guess is that we actually have a wide FOV, such 170°, but off-axis you don't really gather so much info : just usefull to not be ran over by the bus, and the like (pretty usefull, I agree). When it comes to actually look at the things, you have to direct your eyes at it, like when you are reading. Complicated question. You see with your brain as much as with your eyes. You are always scanning with rapid eye movement, so it's difficult to compare eyes with photolenses about FOV. Just guessing here, don't know a thing.
HD

True, the actual focus area of the human eye is only 2 degrees.

[mane162]

Direct tranlation in Spanish seccion, really thanks hdebois :
http://www.maxwellrender.com/forum/view ... 4285#84285

Best Regards

mane162

[Mihai]

hdesbois, thanks a lot for making this guide, but I think you should first describe the different definitions such as depth of field and focal length. You mention those in the beginning but not what they are.

What is depth of field? What is focal length?

By the way, a good thing to know about DOF is to consider it’s only dependent on two parameters : magnification (ratio between the size of the object and the size of the film) and aperture. The more important the magnification, the less DOF you get.

This is confusing, and why don't you mention focal length?

The effect of the of the focal length on the picture is linked to the film size

What effect is that?

[hdesbois]

You're right. Here are some precisions :

Definitions :

Focal lenght : this is the distance from the center of a lens, in mm, at which parallel rays of light passing through it converge. When this lenght is greater than the diagonal dimension of the film, we speak of long (telephoto) lenses. When it's smaller, the lenses are called short (wide angle) lenses. Images formed through long focal lenght lenses appear magnified compared to naked eye sight, and imaged formed through short lenses appear shrinked. In real life, a lense of a given focal lenght gives a sharp image of far away objects when the distance between the center of the lense and the film equals the focal lenght. To get correctly focused images of nearer objects, the lense needs to be moved closer to the film. This is what setting the focusing distance is.

Depth of Field (DOF). The depth of field is the area where an image can be considered as in focus in front and behind the focusing distance. We speak of small (shallow) DOF when very little else is in focus apart what is exactly at focusing distance. When almost everything is in focus, the DOF is big.
The DOF depends on the magnification and aperture. The magnification is the ratio between the size of the object you are photographying and the size of it's image on the film. As film size is, in most cases, small compared to the objects, the magnification is usually much less than 1. It depends on the relative size of the objects and the film, the distance between camera and objets, and focal lenght of the lens.
The bigger the magnification, the less DOF.
The smaller the aperture, the bigger the DOF.

This may seem complicated, but if you try to visualise the ray paths through the lenses, it's easy to understand.



HD

[Xlars]

Thank you very much for this information .. very good for noobs in photography (like me).