 |
|
|
|
|
| |
|
|
|
|
|
||
Film Speed Issues: |
Websites to look at and notes: |
|
| ASA, DIN, ISO | American Standards Association (Name changed to ISO) | ASA, ISO, DIN Good explanation of ASA,ISO,DINVery poor explanation of f-stop |
| ANSI | American National Standards Institute | About ANSI (The official ANSI homepage) |
| DIN | Deutsche Industrie Norm | Very different from ASA, ISO, but still a film speed standard |
| ISO | International Standards Organization (Used to be ASA) | Same as ASA |
Camera Settings On Bright, Sunny Day: |
||
| 1. Shutter Speed | Set at approximately the same as film speed. | |
| 2. Aperture Setting | Set at f/16 | |
Camera Settings With Equivalent Light Values |
||
| Shutter Speed | Aperture Setting | |
| 60 (1/60th of a second) | f/22 | |
| 125 (1/125th of a second) | f/16 |
Halve the time the lens is open; and double the area of the lens opening The film is exposed to the same amount of light as 1/60 @ f/22 |
| 250 (1/250th of a second) | f/11 | Each combination of shutter speed and Aperture setting allows the same amount of light to hit the film as all other setting combinations. |
| 500 (1/500th of a second) | f/8 | There are two things changed as these settings are changed: |
| 1000 (1/1000th of a second) | f/5.6 | 1. Depth of field increases as lens opening (aperture) gets smaller (f-stop gets larger) |
| 2. Ability to stop action increases as shutter speed decreases. | ||
What does this mean?What this means is that, once you have found a shutter speed / aperture combination which is proper for the lighting conditions, you may adjust your camera for different depths of field or action stopping or blurring by changing your aperture and shutter speed at the same time. If you reduce the shutter speed by half and double your aperture area, you have not changed the quantity of light reaching the film, but you have enhanced your ability to stop action. |
||
What the heck are those f/numbers, i.e. f/16, f/8?Those f numbers indicate the relative area of the lens opening. They are NOT the area of the lens opening. |
||
Standard f number |
What it is: |
If your lens aperture is one half of the starting aperture, you are allowing one half of the amount of light to reach the film as with the starting aperture. |
| 1.4 | sqrt2 = the square root of 2 | (sqrt2)^1 (approximate) Aperture is one half the area of f/1 (You'll never see f/1) |
| 2 | sqrt2 * sqrt2 = 2 | (sqrt2)^2 (precise) Aperture is one half the area of f/1.4 |
| 2.8 | 2*sqrt2 = 2.8 | (sqrt2)^3 (approximate) Aperture is one half the area of f/2 |
| 4 | 2.8*sqrt2 = 4 | (sqrt2)^4 (precise) Aperture is one half the area of f/2.8 |
| 5.6 | 4*sqrt2 = 5.6 | (sqrt2)^5 (approximate) Aperture is one half the area of f/4 |
| 8 | 5.6*sqrt2 = 8 | (sqrt2)^6 (precise) Aperture is one half the area of f/5.6 |
| 11 | 8*sqrt2 = 11 | (sqrt2)^7 (approximate) Aperture is one half the area of f/8 |
| 16 | 11*sqrt2 = 16 | (sqrt2)^8 (precise) Aperture is one half the area of f/11 |
| 22 | 16*sqrt2 = 22 | (sqrt2)^9 (approximate) Aperture is one half the area of f/16 |
| 32 | 22*sqrt2 = 32 | (sqrt2)^10 (precise) Aperture is one half the area of f/22 |
| 44 | 32*sqrt2 = 32 | (sqrt2)^11 (approximate) Aperture is one half the area of f/32 |
| 64 | 44*sqrt2 = 64 | (sqrt2)^12 (precise) The setting of choice of Ansel Adams. |
| If your aperture setting is within this range, but NOT a standard f number, then you will not be halving or doubling the light by using that setting. | ||
f-stop = (focal length of lens) / (Diameter of lens) We checked out 400 photography websites searching only for f-stop. Very few people understand or can explain this. Here are some of the better websites with good explanations of f-stop. |
||
| Kalemanis'.. FAQ | Excellent, highly technical (precise, not scary), but very clear and accurate explanation of f-stop. Shows all of the math. | |
| Photography Basics | Excellent, highly technical (precise, not scary), but very clear and accurate explanation of f-stop. Shows all of the math. Superior diagrams. | |
| f-stops | Very succinct. One short paragraph. Very accurate. No math. | |
| f-stops, shutter speeds explained | Pretty good non-technical explanation. Very litte math. Plain English | |
| Photographic Lenses Tutorial | Yessirree Bob. Photography can be technical. LOTSA math. LOTSA definitions. This is by Jacobson. He is widely quoted. | |
| Some Helpful Photography Links | On this page, I hope to get into the details of what photography is all about. I want to get the most precise definitions available. If you know of a good website with accurate information and authoritative definitions, please let me know the URL and I may add it to this page. :If you see anything on this page that is incorrect, PLEASE inform me. |
| Photography | |
| Kalemanis'.. FAQ | |
| Photographic Lenses FAQ | |
| Nikon Photographic Equipment Glossary | |
| minolta_homepage.asp | |
| Pentax - Pentax University | |
| Photography: Getting Technical - F-Stops and Stuff | |
| Welcome to Eastman Kodak Company |