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What Speed of Film Is Most Tolerant to Light?

Researched by Bethany G. 



The purpose of this experiment is to determine what film speed is most tolerant to light out of three speeds of film. (100, 400, 1600 speed film) 

I became interested in this idea because I have wanted to be a photographer for awhile and have been interested in how the film exposure process works.  I have wondered how light hits the film and how it is effected. 

Photographers can use the information gained from this experiment to see what speed of film will not be ruined or is most tolerant, when using the wrong aperture two settings above and below the right aperture. 


My hypothesis is that 100-speed film is most tolerant, going two aperture settings above and below the right aperture for that speed of film. I think 400 speed film is second most tolerant, and 1600 speed film third most tolerant. 

I base my hypothesis on data collected by photographers saying that greater aperture with slower film does not over expose film. They also say a greater aperture setting is best used with slower film. Slower film is less sensitive t light. Faster film is more sensitive to light. 

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The constants in this study were: 
1 Brand  of film 
2 Camera  
3 Room 

The manipulated variable was 
Film speed 

The responding variable was the light hitting the films.

To measure the responding variable I am going to use a colorimeter to measure how much light is in the picture. 







Rolls of film ASA 100,400,1600





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1. Gather materials  
2. Set the camera on the tripod  
3. Put 25 speed film in camera  
4. Using a light meter, determine the aperture setting for 1/60 shutter speed, and then go 2 apertures up and 2 apertures down. 
5. Take 8 pictures on aperture setting 5.3 on 400-speed film (Two apertures below ) 
6. Take 8 pictures on aperture setting 6.7on 400-speed film (Zero) 
7. Take 8 pictures on aperture setting 9.5 on 400-speed film (Two apertures above) 
8. Put 100 speed film in camera  
9. Take 8 pictures on aperture setting 2 on100-speed film (Two apertures below ) 
10. Take 8 pictures on aperture setting 3.5 on 100-speed film (Zero) 
11. Take 8 pictures on aperture setting 5.3 on 100-speed film (Two apertures above) 
12. Put 400 speed film in the camera  
13. Take 8 pictures on aperture setting 6.7 on 1600-speed film (Two apertures below ) 
14. Take 8 pictures on aperture setting 9.5 on 1600-speed film (Zero) 
15. Take 8 pictures on aperture setting 16 on 1600-speed film (Two apertures above) 
16. Develop the film 
17. Use colorimeter to measure how much light is in each picture 
18. Average  the results of each film  and aperture setting ,then find the difference of each three averages  the different  film speed and the one with the largest number is the least tolerant etc. 

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The original purpose of this experiment was to determine what film speed is most tolerant to light of the three speeds of film (100,400,1600 ASA). 

The results of the experiment were 100 ASA resulted in a difference of 3.05 between the +2 f-stops and -2 f-stops demonstrating the least tolerant film. 400 ASA resulted in a difference of 2.84, second most tolerant. 1600 ASA resulted in a difference of 2.15 most tolerant of the three speeds tested.

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My hypothesis was is that 100 speed of film is most tolerant, going two aperture settings above and below the right aperture for that speed of film. I think 400 speed film is second most tolerant, and 1600 speed film third most tolerant.  
The results indicate that this hypothesis should be rejected because1600 -speed of film is most tolerant, 400 speed film is second most tolerant, and 100 speed of film is third most tolerant.

Because of the results of this experiment, I wonder if a speed of film I didn't test is more tolerant than 1600s-speed film. 
If I were to conduct this project again I would use more speeds of film to find out which speed of film is most tolerant out of all speeds of film. I would also want to use the negatives instead of the pictures.  



 Photography has many different aspects. It can be used for such things as taking pictures for fun, experimenting, and professional photography. The goal of this report is to give you a better understanding of the different aspects of photography.


In the early fifteen hundreds the first type of camera was invented by Leonardo da Vinci. This camera was called camera obscure (dark chambers.) Artists often used the camera obscure. The camera obscure was a large camera.  It was large enough for a grown man to fit in. The artists would use the upside down image produced by the light from a hole in the wall. They would sketch the image that was projected on to the wall. Johnann H. Schulze is credited with discovering that silver salts are light sensitive. Sir Humphry Davy started to experiment with silver compounds. The earliest photographs recorded are called heliographs. In 1831 Louis Jacques Mande Daguerre made photographs that were slowly darkened when exposed to light. Dagrerre created permanent photos by coating the photograph with a strong solution made of regular table salt. After about 1840, cameras were greatly improved. In 1888, the Kodak camera was put on the market.  The Polaroid process was announced in 1947. Now the digital camera is the new thing. 


The most common compound used to make film is silver halide crystal. It is a kind of salt. The salt is made up of chemicals called halogens. Halogens are chemicals called bromine, or iodine. These chemicals are photosensitive. Color film has different types of dyes, couplers, and other chemicals.  
The speed of film is based on how sensitive the film is to light. Fast film is very sensitive. Slow film is not as sensitive. A fast film can produce a quality picture with less light than slower film with less light.  

Aperture Settings and the Shutter

The aperture setting is like the human eye. The aperture or f-stop controls how much light the film is exposed to.  The light passes through the aperture. The aperture is measured by its diameter of the widest ray of light that can enter the lens. The diaphragm controls the size of aperture opening. 
           The shutter is used to let the light onto the film. It is lifted or opened when the button is pushed. The speed of the shutter can be changed anywhere from two seconds to one  
One-thousandth of a second. The shutter speed depends on the type of camera. You use the different shutter speeds to add more or less light in a certain amount of time. A slow shutter will allow the picture to have more light. A picture taken with a faster aperture will not have as much light as a slower aperture.  


Light and Lenses 

Photography in Greek means, "drawing with light." Too much light can ruin a picture but so can too little. It is important to be able to measure the amount of light. Too much light can over expose the film and too little light can underexpose the film. In a picture, flare is unwanted light that causes weird reflections and loss of contrast on the film. It often happens when the sun is in front or to the side of the lens. Light is the ingredient that makes the picture. 
Lenses can be plastic or glass. They do get scratched easily. There are two kinds of lenses. Concave lenses curve inward. Convex lenses have an outward curve. In photography there are three specific kinds of lenses. They are normal, wide angle, and telephoto. In a normal lens, the viewing is about 50 degrees. Everything appears normal in size and shape according to Groliers 1997. A wide-angle lens has a larger view. It is used to make smaller objects look larger or larger objects appear close up. The telephoto has a long focus and has a smaller view than a normal lens. It shows detail. 


From the camera obscure to the digital camera of today, photography has greatly changed over the years. Photosensitive chemicals produce an image when exposed to the light. Aperture and shutter speeds both influence the quality of the picture. The lenses determine what the camera views, for example how close up or far away an object is. The camera enables us to freeze the past in an unforgettable image. 

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Palmer Brian, Traub, Charals H., Tweety, Karen "History of Photography" Encarta Deluxe  2000

"Exposure" Available at

Grudberg Andy   "Aperture "Encarta Encyclopedia Deluxe, 2000

"Film and Filters" Compton’s Interactive Encyclopedia, 1995

Young Scientists  Volume 2 Chicago IL. World Book Inc.,1997

Edom C. Clifton "Photography History" World Book Encyclopedia, 1978  
   Volume 15,Pg.380j-380.m 


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