Trying to understand "wide angle" lenses

[TheSunsAnvil]

Intuitively I would have thought that the view angle (or how much of the scene we see) is a fixed function of the sensor size vs. focal length, somewhat synonymous with magnification, yet there are Xmm lenses which are designated as "wide angle" while others are not. What am I missing in my understanding here?

 

[olliess]

TheSunsAnvil wrote:

Intuitively I would have thought that the view angle (or how much of the scene we see) is a fixed function of the sensor size vs. focal length, somewhat synonymous with magnification, yet there are Xmm lenses which are designated as "wide angle" while others are not. What am I missing in my understanding here?

Maybe "advertising"?

Got any examples in mind of this inconsistent labeling practice?

 

[Mike_PEAT]

Higher-end lenses don't need to be advertised as such since those buying them would be more experienced and know what a lens is at a certain mm. Do you really need to be told if a lens is super-wide, wide, normal, telephoto, ultra-telephoto?

There are exceptions where lenses can have the same mm but produce different images on the same camera, 16mm or less can either be a fisheye lens (producing bulging images), or rectilinear corrected lens (producing straight lines).

 

[TheSunsAnvil]

So really "wide angle lens" is simply lenses shorter than a certain arbitrary focal length?

My confusion came less from marketing and more I think from articles/discussions/reviews where something like a 18-55 kit lens might be described as a "wide angle zoom lens" while others describe a lens of similar range as being a "standard zoom".

 

[TheSunsAnvil]

Thanks.

 

[olliess]

TheSunsAnvil wrote:

So really "wide angle lens" is simply lenses shorter than a certain arbitrary focal length?

Hehe... you can get into an unending debate about what is a "normal lens," but once you figure that out then yes, anything wider is a wide angle lens.

My confusion came less from marketing and more I think from articles/discussions/reviews where something like a 18-55 kit lens might be described as a "wide angle zoom lens" while others describe a lens of similar range as being a "standard zoom".

I guess that's more just loose usage. It's a "standard zoom" because it comes standard with most cameras. It's also (sort of) a "wide zoom" (although it really isn't all that wide on APS-C).

Yeah, whatever, right?

 

[BobSC]

TheSunsAnvil wrote:

So really "wide angle lens" is simply lenses shorter than a certain arbitrary focal length?

My confusion came less from marketing and more I think from articles/discussions/reviews where something like a 18-55 kit lens might be described as a "wide angle zoom lens" while others describe a lens of similar range as being a "standard zoom".

It's just a marketing term. Like "nutritious."

On an APS size sensor, the dividing line is around 35. Anything shorter is wide-angle and anything longer is telephoto.

 

[Jeff]

TheSunsAnvil wrote:

Intuitively I would have thought that the view angle (or how much of the scene we see) is a fixed function of the sensor size vs. focal length, somewhat synonymous with magnification, yet there are Xmm lenses which are designated as "wide angle" while others are not. What am I missing in my understanding here?

Your intuition is partly right, the angle of view is determined by the ratio of sensor size to focal length. To get a wide angle of view you need a shorter focal length lens *and* that lens has to able to cover the full width of the sensor. That second detail is very important.

For example, suppose you have a 25mm lens. If it could be mounted on a full frame 35mm format camera like the Nikon D800, and if it could fully cover the sensor, then it would be wide angle lens.

Mounted on micro Four Thirds camera it would be a normal perspective. To keep it smaller and lighter, it would likely be designed only to cover the smaller sensor, and therefore not usable as a wide angle lens on a larger format.


Did that help?

--

Jeff

jck_photos’s albums | Flickr

www.flickr.com

 

[Barrie Davis]

Jeff wrote:

TheSunsAnvil wrote:

Intuitively I would have thought that the view angle (or how much of the scene we see) is a fixed function of the sensor size vs. focal length, somewhat synonymous with magnification, yet there are Xmm lenses which are designated as "wide angle" while others are not. What am I missing in my understanding here?

Your intuition is partly right, the angle of view is determined by the ratio of sensor size to focal length. To get a wide angle of view you need a shorter focal length lens *and* that lens has to able to cover the full width of the sensor. That second detail is very important.

For example, suppose you have a 25mm lens. If it could be mounted on a full frame 35mm format camera like the Nikon D800, and if it could fully cover the sensor, then it would be wide angle lens.

Mounted on micro Four Thirds camera it would be a normal perspective.

Whoops! 'Perspective' is the wrong word here, Jeff.

Lenses do not have a perspective, as such.

Instead, it is positions in space that have a perspective.... wide angle lenses including more of the available "perspective" within frame, and tele lenses rather less of it...

.... but the perspective of both shots, meaning the size relationships between near and far subject elements seen from the same point is space, is.... -(pause for effect)-.... identical.

I just thought I'd mention it, okay? ;-)

 

[Jeff]

Barrie Davis wrote:

Jeff wrote:

TheSunsAnvil wrote:

Intuitively I would have thought that the view angle (or how much of the scene we see) is a fixed function of the sensor size vs. focal length, somewhat synonymous with magnification, yet there are Xmm lenses which are designated as "wide angle" while others are not. What am I missing in my understanding here?

Your intuition is partly right, the angle of view is determined by the ratio of sensor size to focal length. To get a wide angle of view you need a shorter focal length lens *and* that lens has to able to cover the full width of the sensor. That second detail is very important.

For example, suppose you have a 25mm lens. If it could be mounted on a full frame 35mm format camera like the Nikon D800, and if it could fully cover the sensor, then it would be wide angle lens.

Mounted on micro Four Thirds camera it would be a normal perspective.

Whoops! 'Perspective' is the wrong word here, Jeff.

Lenses do not have a perspective, as such.

Instead, it is positions in space that have a perspective.... wide angle lenses including more of the available "perspective" within frame, and tele lenses rather less of it...

.... but the perspective of both shots, meaning the size relationships between near and far subject elements seen from the same point is space, is.... -(pause for effect)-.... identical.

I just thought I'd mention it, okay? ;-)

 

[ARShutterbug]

Wide-angle in 35-mm photography is usually provided by a lens that has a focal length less than 50 mm. In practical use, what means "wide" depends on the size of the scene. If you're doing a landscape at long distance, "wide" may be a lens with a focal length of 200 mm or more.

 

[Mystery member]

Returning to the original question...

Traditionally, on 35mm (film) cameras, anything much less than the usual 50mm lens was considered "wide angle", since 50mm gave roughly the view of the human observer. Some cameras (e.g. Konica) came with 40mm lenses as standard, and this was described as being somewhat wide-angled.

Cameras with smaller sensors require shorter focal length lenses for a wide-angle view. e.g. Nikon DX cameras are supplied with a 18-55mm zoom, which at the lower end is equivalent to a 27mm lens on a full-frame camera, let's call that a mildly wide-angled lens, with zoom capability up to 82mm equivalent (factor x 1.5).

Compact digital cameras often have 6mm sensors, so the effective focal lengths can be quite long ( x 6).