I want to understand different types of lenses.

knifewrench

New member
Ok, so there are a lot lenses out there for all types of shots. I want to know what the different types of lenses are used for. The lenses I know of are Prime, Zoom, Wide, Telephoto, and video. I want to know what each lenses does, and if there are others ones, let me know. Thanks a lot.
 

LeZombi

New member
Prime just refers to a fixed focal length lens usually around 25mm to 35mm. It gives you the perspective pretty close to the human eye.

Zoom as you probably know changes in focal length. They usually go from about 18mm-120mm. Zoom lenses have greater depth of field.

Wide is pretty much anything under 25mm and it is the most distorted. It allows you to fit a lot in the frame because it sort of shrinks it and makes things smaller in the frame. There is usually bending on the edges of the frame so look out for that unless its a desired effect. It also gives a greater depth of field meaning more things remain in sharp focus distant or close. Fish eye lenses are wide angle too but extremely wide.

Telephoto is a longer lens and above 35mm. It is more "zoomed in." I don't want to use that word but I can't think of another way to explain it right now. It makes things larger in the frame and appear flat and closer together than they actually are. Depth of field is much shallower on these lenses meaning not everything is in sharp focus and you have to adjust the focus to what you want to bring attention to.

Video lenses are zoom lenses with great depth of field. The lenses are generally short.

I'll now explain Depth of Field if you were wondering. Depth of field is the range of distance within the subject that is acceptably sharp. The depth of field varies depending on camera type, aperture and focusing distance, although print size and viewing distance can influence our perception of it. 35mm film has shallower depth of field than 16mm. Video generally has the greatest depth of field. Shallow means that more things are out of focus and great or wide depth of field means more things remain in focus.

To get shallow depth of field don't use a wide angle or zoom lens. Open up your aperture. Light effects the depth of field. More light increases the depth of field because you have to stop down your lens. If you're using video its easier to change your depth of field because you have the option to change shutter speed along with your iris. Also adding an ND filter will allow your lens to open up more in better lit conditions so you can still have shallow depth of field. You can do all of this with film too but you will need a camera that allows you to adjust the shutter angle and you must have the ND filter to screw on the lens

I hope this is helpful to you.

Jon Schweigart
Student DP
Buffalo, NY
 

Lazlo

New member
Sorry, but there were some major factual inaccuracies in the second post:

Prime: Yes a prime is a fixed focal length lens... by definition, not a zoom. But it doesn't necessarily give you a "perspective" of the human eye. A 25mm prime is no more or less a prime than a 150mm fixed focal length, and obviously those two give two very different perspectives. In summary, a prime is simply a lens that has a fixed focal length. This is useful because since there is less glass, you generally get a sharper and more defined image. The rule of thumb is basically that the less glass in front of the lens, the less distortion (i.e. vignetting, color distortion, sharpness).

Zoom: A zoom lens does not inherently have greater depth of field than a prime. Depth of field is controlled by focal length (the longer the focal length, the less the depth of field), f-stop, and distance from subject. More accurately, a wide angle lens has greater depth of field than a telephoto lens. The fact that a lens zooms or not does not have anything to do with whether or not it has greater depth of field or not. Also, zooms do not "usually go from 18-200mm". There is a huge range of zoom lenses for every situation.

Wide angle lens: A wide angle lens is defined as any lens that is under 50mm. 50mm roughly simulates what one sees if one eye is covered, and is considered the middle ground that separates wide from telephoto (this is in 35mm standards...). Maybe the first post was in reference to 16mm cinematography... A 49mm lens, if such existed would be considered a wide angle lens. In the wide angle realm, you can get into fisheyes where there is controlled distortion, and other special effect lenses. On high end wide angle lenses, distortion is almost non-existent, and is primarily controlled 1. by the quality of the lens and the glass, and then 2. by the distance the lens is from the subject. The closer you are to a subject with a wide angle lens, and the wider the lens, the greater the distortion.

Telephoto lens: This is any lens that is over 50mm in focal length. They inherently give the ability to achieve a shallower depth of field. Telephotos compress objects in space, and can be used to make distant subjects appear much closer than actuality. The difference between a telephoto and a macro lens is as follows: A macro brings objects that are close even closer, whereas a telephoto brings objects that are far away, closer. This is an important distinction, because many telephotos have a minimum focus of at least 3 ft, although this varies with the focal length obviously.

Video Lenses: Whatever this really means..... Just to clear this up, a so-called "video lens" does not have any shallower or greater depth of field than a non-video lens. In this scenario, the depth of field is determined by the CCD inside the camera. Since most consumer and prosumer video cameras have extremely small sensor chips, there is greater depth of field. If you want a more complete answer on depth of field, ask M. David Mullin, who is a technical genius at this stuff (he'll probably start with the circle of confusion). I understand all the principles of depth of field, but have not internalized all of the concepts in such a way that I can express them verbally yet...

As far as things to remember, depth of field is affected by:
1. Distance of camera from subject
2. Focal length of lens.
3. F-stop
4. If more than one subject, distance between subjects in relation to camera.

I'd highly recommend checking out Blaine Browns book on cinematography, or also the new one by Kris Malkowitz and M. David Mullin is good as well. And also checking out cinematography.com, which is a phenominal resource of world class cinematographers sharing knowledge.
 
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