Originally posted by Gooshin 55mm focal length (physical) will provide you with the perspective of human vision at any distance or field of view.
This may be true to an extent when you are placing the camera to you eye (with current viewfinders, that is), but not when you see the resulting photograph. A "normal" length lens is a lens that captures photos that when viewed from the "normal viewing distance" give the same perspective as human vision. It changes with the size of the film/sensor. It correlates directly only to the angle of view (or field of view when used synonymously), and does not correlate directly to focal length any more than it correlates directly to film/sensor size.
Really, even when placing the camera to your eye, it all depends upon the viewfinder and how much it might magnify or reduce the image to your eye. So you should be able to get the same behind the camera feeling with a normal length lens for any camera by using a viewfinder that magnifies or reduces the image the correct amount to match human vision. Of course such a viewfinder may or may not be available for any given camera.
Quote: this is why more and more i have been wanting a full frame camera and enjoy using my film camera once in awhile
this is also why i want a MF camera even more, because with a 50-55mm lens, when you bring the camera up to your eye, you get zero perspective distortion, or, magnification as one could say and a HUGE field of view, to capture the world as i see it.
if you are looking at a bottle 5 feet away, when you bring up your 55mm equiped camera (ANY camera) the bottle will still look as if it is 5 feet away.
when you start increasing the focal length (physical), when you look at that bottle through the viewfinder you will feel as if the bottle is closer to you than 5 feet
when you start decreasing the focal length, when you look through the view finder you will feel as if there is a greater distance between you and the bottle than 5 feet.
again.. ON ANY SIZED SENSOR/FILM whatever
Again this depends entirely on how much your viewfinder reduces or enlarges the image, and does not correspond with the effect on the actual photographic results, which are entirely dependent on the angle of view covered by your focal length/sensor size combination (on whether you are using a normal lens or not).
Quote: field of view, is a different beast all together.
a 5-10mm lens on a point and shoot gives you similar FIELDS OF VIEW, but it most definetly does not give you the same sense of perspective that you would have gotten otherwise. When using a point and shoot, you always feel like you are not in the shot, because even though you are standing 5 feet away from your subject, it feels like you are like 50 feet away,
you are shooting someones face on a point and shoot, who's face is more than than the size of the LCD screen, yet they fit on the LCD screen entirely, with their shoulders, and the drunken stranger to the side....
This is entirely the result of using tiny LCD screens on the backs of cameras as viewfinders (I don't like them for that either) rather than anything to do with focal length. Remember, their face is much bigger than a 35mm piece of film as well, yet you manage to fit them on there. A 35mm equivalent sensor camera with a 50mm lens could be equipped with a tiny LCD screen also, and you would still hate the view on the screen just as much as you do now.
What you hate when behind the camera is the apparent size of objects in the viewfinder as compared to when you take the camera away. This is dependent on the viewfinder. Ideally, a normal lens for your camera should always look normal through your viewfinder because that would give you the best feeling of how the photo will turn out. Unfortunately this is not the case, so you have to rely on knowing what is a normal length lens for your camera format to know how the photo will turn out.
The definition of a normal lens is based on the idea that the resulting photo will be viewed from a distance about equal to the diagonal of its print. That is, an 8 inch by 10 inch photo will be viewed from about 13 inches away, while an 8 foot by 10 foot poster will be viewed from about 13 feet away, etc.
Assuming this, to achieve normal vision perspective from the camera you need to focus the image on the film or sensor from a distance of the same one to one ratio to the diagonal of the film or sensor. If you pick a shorter length, then it will put too much in the photo, shrinking the image, and you will get extension distortion that makes everything seem farther away and farther apart. If you pick a longer length, then you will put too little in the photo, magnifying the image, and you will get compression distortion that makes everything seem nearer and closer together.
Of course, in practice, sometimes you want wide angle or telephoto shots, perspective distortion and all, so the options are good.