The significance of lense type

David Calson · July 25, 2006

Hi, I'm all about learning the ins/outs of cameras, but I can't put my finger on lense knowledge. I know what a long lense does vs. wide but I can't figure out why you would choose one or the other for a particular scene. Also, I feel somewhat clueless when it comes to spotting which particular lense was used from scenes of movies I've watched. In short, I know lense types are an important part of the filmmaking process but I can't get a handle as to what I should know about them and why.

David Mullen ASC · July 25, 2006

Hi, I'm all about learning the ins/outs of cameras, but I can't put my finger on lense knowledge. I know what a long lense does vs. wide but I can't figure out why you would choose one or the other for a particular scene. Also, I feel somewhat clueless when it comes to spotting which particular lense was used from scenes of movies I've watched. In short, I know lense types are an important part of the filmmaking process but I can't get a handle as to what I should know about them and why.

You just said that you know what a wide or a long lens does... but then you said you can't tell which are used in a scene in a movie. So do you know what they do, what look they create, or don't you?

Also, remember that some lenses are medium focal length and thus don't exhibit the visual artifacts of wide or long lenses.

A wide-angle lens has a greater field of view, it sees more of the space. A long lens has a narrow field of view, seeing only a small portion of the space. So right there you see one of the reasons why you might chose one or the other. You're in a small room with the camera backed up into a corner and you want to see a lot of the room, you use a wide-angle lens. You want to show something small at the opposite end of the room and enlarge it so you can see it better without moving the camera closer, you use a long lens.

A wide-angle lens exaggerates vanishing-point perspective -- objects recede faster and shrink in size faster as they get farther away; close objects seem bigger than normal in the foreground. So wide-angle lenses also increase the feeling of forward/backward motion since you "feel" the distance travelled more obviously.

A long lens compresses space, making near and far objects seem more similar in size and flattening the perspective. Objects moving forward and back seem to take longer without changing size much (on the other hand, sideways motion and panning look more exaggerated.)

Also, you sense that the camera is physically closer to the subject when shooting close-ups with a wide-angle lens and you feel that the camera is looking from a farther away position when you are shooting close-ups with a telephoto lens.

Just go and shoot a medium close-up with a wide-angle and telephoto lens and you'll see the difference in effect.

Laurent Andrieux · July 26, 2006

I can't put my finger on lense knowledge

It's a good thing you want to put your finger on lense knowledge but as a starting point, it's a better thing that you don't put your fingers on a lens at all !

I mean the glass... :D

It can cause damages that can never be repared.

David Calson · July 27, 2006

Thanks for clearing things up David. Yeah the practial cinematic purposes was the part that confused me. Also, are there like standard increments when it comes to lenses (Ex. 35mm...90mm...125mm) with no obscure mm's inbetween (62mm)? Are lense sizes like f/stops in that there's only a certain number of them (ie there's nothing below or above f/1 and f/22)

Scott Fritzshall · July 27, 2006

Thanks for clearing things up David. Yeah the practial cinematic purposes was the part that confused me. Also, are there like standard increments when it comes to lenses (Ex. 35mm...90mm...125mm) with no obscure mm's inbetween (62mm)? Are lense sizes like f/stops in that there's only a certain number of them (ie there's nothing below or above f/1 and f/22)

The shortest lens for a 35mm camera I've heard of is 8mm I think, and there are some that are really long. A quick look at Canon's site shows they have a 600mm lens- that's for still photography, and I don't know how long they go for motion picture cameras, but they can be really long.

F-stops, by the way, are the ratio between the aperture of the lens and the focal length, and so they can go lower than 1 and higher than 22.

David Mullen ASC · July 27, 2006

A zoom is a variable focal length lens that can go to any number within its designed range.

There's no reason why a prime lens can't be some odd number like 43mm, let's say, only that a lens manufacturer isn't going to build a prime for every number increment. And since most make a series with a popular 50mm lens for 35mm photography, the jumps above and below 50mm tend to be in roughly standard leaps, although not exactly. For example, a basic series may be: 18mm, 25mm, 35mm, 50mm, 85mm, 100mm, but another series or another manufacturer may make a 75mm instead of an 85mm, or a 27mm instead of a 25mm, etc.

And over time, they may make some inbetween lenses (like a 40mm to go between a 35mm and 50mm) because of repeated requests from customers.

Most prime lenses start out around T/2.0 or so, but there are faster lenses that start at T/1.4 or T/1.3, and a few 50mm lenses that open to T/1.1 or T/1.0. Kubrick had a special 50mm Zeiss lens made for NASA that opened to T/0.7. Telephotos tend to not open as wide but stop down further than T/22.

Daniel Stigler · July 27, 2006

A quick look at Canon's site shows they have a 600mm lens- that's for still photography, and I don't know how long they go for motion picture cameras, but they can be really long.

The longest lens with a PL mount i know of is a 1000mm. As far as i know there are two of them available in Germany. Vantage makes a huge zoom that goes from 150mm to 450mm.

David Mullen ASC · July 27, 2006

In 35mm motion picture photography, almost every prime lens over 200mm is an adapted still camera lens, usually Nikon or Canon.

Brad Grimmett · July 27, 2006

Since we're talking about lenses....can anyone tell me how modern lenses relate to the lenses that were referred to as 2 inch and 3 inch, etc....

I did a movie recently with an operator who would ask for lenses by inches, which I've heard about before, but I don't know the conversion.

What are the conversions and what is the reason for the original names?

David Calson · July 27, 2006

Thanks guys, once again VERY helpful!

Stephen Williams · July 27, 2006

Since we're talking about lenses....can anyone tell me how modern lenses relate to the lenses that were referred to as 2 inch and 3 inch, etc....
I did a movie recently with an operator who would ask for lenses by inches, which I've heard about before, but I don't know the conversion.

What are the conversions and what is the reason for the original names?

Hi Brad,

An inch is 25.4mm so a 2 inch lens is basically a 50mm and the 3 inch is about 75mm. I have a set of super Balitars that are in mm except for the 3 inch!

Stephen

Leo Anthony Vale · July 27, 2006

... but I don't know the conversion.
What are the conversions and what is the reason for the original names?

---So, in grade school you didn't have a ruler with inches on one edge and mm/cm on the other edge?

Anyway, they were "named", numbered would be a more accurate term, prior to the victory of the International Metric Cartel Conspiracy.

Fortunately the victory isn't complete & the American Car Cartel still uses mileage.

---LV

Robert Hughes · July 27, 2006

Thanks for clearing things up David. Yeah the practial cinematic purposes was the part that confused me. Also, are there like standard increments when it comes to lenses (Ex. 35mm...90mm...125mm) with no obscure mm's inbetween (62mm)? Are lense sizes like f/stops in that there's only a certain number of them (ie there's nothing below or above f/1 and f/22)

In 1908 the International Optical Commission of Berne, Switzerland issued a standard exposure system using only 22 stops, as wild stops were an endangered species; the last ones died out and became extinct during the 1937 Spanish Civil War. Only 22 remained, and were sold off to the highest bidders in France, Germany and Britain. After the War, Japan successfully cloned wild stops from recycled American bomb sights and miscellaneous telephone parts. There's plenty to go around now...

John Pytlak RIP · July 27, 2006

25.4 millimeters = 1 inch is an exact relationship.

Lens f/stops increment as the square root of 2. The usual sequence is:

0.7, 1.0, 1.4, 2.0, 2.8, 4.0, 5.6, 8.0, 11, 16, 22, 32, 45

Lots of lens and optic tutorials on the Internet, some by individuals:

http://en.wikipedia.org/wiki/F-number

http://www.kevinwilley.com/l3_topic01.htm

http://www.mir.com.my/rb/photography/fotot...tmls/depth.html

http://www.mir.com.my/rb/photography/fotot...er/aperture.htm

http://www.uscoles.com/fstop.htm

http://www.shutterfreaks.com/Tips/ControllingDOF.html

http://www.cybercollege.com/tvp010.htm

Laurent Andrieux · July 27, 2006

Hey, Hey, gentlemen, I remind you, if I may do, that meters and its substandards (km, mm...) is the only official unit for distance measures !

Feet and inches is an illegal, subversive, democratie killer unit that should be avoid in any case !

We, in France, have special police sections that come on shootings as to check tape measures, focus rings and follow focus, as well as stock reports as to ban the bastard !

Hoppefully, we did not yet notice any attempt for lenses to enter the country as imperial, and they know they have to be aware of being engraved in the only one unit we allow !

Just kidding, we use feet and inches every day for focus pulling, but lenses and stock reports are always in meters... ;)

Brad Grimmett · July 28, 2006

I guess if I had thought about it (or researched it) for more than 30 seconds I could have figured it out on my own. Well....maybe not! :huh: Thanks for the explanations. I was too busy to see what lens they put up when he was asking for lenses in inches.

David Calson · July 30, 2006

Also, are there any important rules of thumb when it comes to lenses?

Laurent Andrieux · July 30, 2006

A lens is a very complecated technical object ! What do you mean by a "rule of thumb " ?

Leo Anthony Vale · July 31, 2006

Also, are there any important rules of thumb when it comes to lenses?

---Don't get thumb prints on the glass.

---LV

Daniel Madsen · July 31, 2006

An MTF Chart is used to express the resolving power of a lens in terms of contrast and resolution. These types of charts are not too uncommon. If you do some research you will find that some lens makers place emphasis on contrast while others, resolution. MTF charts are discussed in some of the old ASC manuals.

Laurent Andrieux · August 26, 2006

Just to clear up something : when I said lenses are usually calibrated in millimeters, I was talking of the focal lengths only (that being the subject). The distance values are both in feet and meters...