Are wide angle lenses defined as wide angle based on focal size alone?

Question

I see lenses that are 24mm and are calling themselves wide angle yet there are 18mm that is not considered wide angle (18mm-70mm D70 kit lens). Is the definition of a wide angle just based on the focal size or is it also based on the convexity of the front glass?
I understand about crop factors but some of the photos I see shot with a D70 and a 18mm wide angle look like they were shot wide and others don't.

As an addendum: I have shot film and used prime lenses. My question has nothing to do with the crop factor as I pointed out. It has to do with why one 25mm lens can be called wide angle and shoot wide while another is a 25mm that doesn't have that feel of shooting wide.
Attempting to answer with a demeaning air of (false) superiority does not mean the actual question was answered.

Answer 1

I think the problem is that there is no line in stone saying where wide angle begins and normal ends.

I answered this for a beginner a while ago, so this information is below your level, but perhaps it will still be helpful. The important thing here is that I deduced these values by doing various searches on B&H Photo and just seeing what focal lengths THEY chose to use to catagorize the lenses.
~~~~~~
Here's the old answer. It is in 35 mm equivalents.

Ultra Wide - 10-20
Wide Angle - 24-35
Normal - 45-55 (50 mm is the accepted "normal")
Medium Tele - 85-135
Telephoto - 150-300
Super Tele - 400-600
~~~~~~
Another very important factor to consider in the appearance of the photograph is the angle of view at which the picture was taken, which is determined by the distance from the subject. If you are close to the subject and use a 25 mm lens, you will see some distortion of the image at the edges and this gives it that "wide" appearance. If you are far away, there is less evidence of distortion. This is part of the reason it is nice to use an 85-105 mm lens (35 mm equiv) for portraits. You can fill the frame with a narrow angle of view, which is more flattering. If you tried to fill the frame with a 24 mm lens, the subject's nose would appear to take up half of his face because you'd be so close to him. Or her.

Answer 2

Yes, it is defined by the focal length. In 35mm photography a "Normal" lens is considered to be a lens in the range of about 40-50mm since the diagonal measurement of an image on 35mm film is about 43mm. Anything wider than normal is considered a wide angle, and anything narrower is considered a telephoto. With Nikon digital the sensor size is smaller and the diagonal of the sensor is measured around 28mm. Thus a "Normal" lens on a Nikon digital SLR is around 28mm, give or take. All of a sudden, a 24mm lens isn't very wide any more on a digital, but is on a film body.

The 18-70mm AF-S DX lens is a wide-to-medium telephoto zoom lens. 18mm is definitely considered a wide angle focal length on a Nikon DSLR - always.

Answer 3

Others have already given a lot of information, but I feel that it might still be confusing. Here's the bottom line: focal length alone *does not* determine if a lens is "wide angle" or not. Instead, it is the ratio of focal length to the film or sensor size, usually measured as the diagonal of the film or sensor. The result of this ratio is the angle of view generated by the lens/film or lens/sensor combination.

So, for instance, with 35mm film, the diagonal is about 43mm, thus a lens that will produce what is considered a "normal" perspective would ideally be 43mm, producing an angle of view of 53 degrees. Some lenses (Pentax) are actually made at this focal length for this reason. But most "standard" lenses for 35mm cameras have been 50mm and there are a few that are 40mm.

Again for 35mm film cameras (or "full frame" digital sensors), wide angle lenses start at 35mm and go shorter from there. Typical focal lengths for "wide angle" lenses in 35mm range from 20mm (about 90 degree angle of view) at the shorter end to 35mm (about 60 degree angle of view) at the longer end.

However, if you look at typical digital camera sensor sizes, these same focal lengths do not equate to the same angles of view. A 28mm lens (considered moderately wide for 35mm film cameras) gives an angle of view of about 55 degrees - certainly not "wide" but much closer to "normal" for most photographers. So to get a truly "wide" lens for a typical digtial SLR, you would need to start at 24mm and go down from there.

Hope this helps.

Answer 4

Basics of a lens. Normal angle of view of a normal healthy human with both the eyes is around 45 degrees horizontal.
and little less vertical.

Which ever lens less than normal angle is Tele or Narrow angle lens and any lens more than normal angle is wide angle lens.

Take a look at any lens company's lens range spec page,
you will see a column showing Angle of view.

The focal length of a lens for a format decides the angle of view of that lens, i.e. 50 mm lens for 35 mm film format has normal angle of view. 35 mm and smaller focal length lenses all are called as wide, super wide or ultra wide lenses. Lenses from 135 mm and more focal length are tele, super or ultra tele lenses.

In case of modern compact digital cameras the CCD or CMOS sensor are small in size like 12 mm diagonal, to find out which focal length is wide it is better to look at lens spec sheet for viewing angle.

There is mathematics involved in finding out focal length and angle of view relation for any lens.

For 6 x 6 cm medium format camera, 85 mm focal length has normal angle of view. 45 mm focal length is the widest angle of view lens for this format.

Caution for using wide angle lenses, it creates noticeable perspective distortion for human figures, particularly in group, on extreme sides, person's body, mainly face looks very deformed.

Wide angle lenses are good for landscapes.

Answer 5

z