Written by: Digital Photography

Photographic film and photographic paper are basically a gelatin-like emulsion, loaded with light sensitive silver salts on an acetate base.

This information is also useful for digital camera users. The only real difference is that digital uses a light sensitive chip instead of light sensitive film, so there is no need for chemical processing. Digital users should read on anyway, for this will provide a great deal of information that will be useful later on.


To understand film and photo paper think of Jello on a sheet of clear plastic. The Jello has a bunch of light-sensitive salt crystals suspended in it.

THINK ABOUT SILVER, this metal is so light-sensitive it will turn black – tarnish – when exposed to light. The light sensitizes the silver and the oxygen in the air reacts with the silver that was hit by light and “oxidizes” -tarnishes – it.

NOW PAY ATTENTION!!!!

This is illustrates what a cross-section of film might look like.

The “orange” bottom layer is the acetate (film) base, and the emulsion on top is laden with silver salt crystals

Film Photography

Those salt crystals are sensitive to light, and when hit by light rays and then developed by chemical oxidation, those salts will turn dark.

Film Photography

Salts not hit by light (i.e. black or dark rays) will be washed away. Think about this until it is clear and fixed in your mind.

Below is a piece of film that has been exposed (a negative).

Football Film Photography

Below is photographic paper that is exposed from that negative.

Film Photograph

Look at the white jersey above, his number – 84 – appears black. Now that “white” jersey appears black and the number is white.

HERE IS WHAT HAPPENED.

FIRST, TO THE FILM ON THE LEFT:

When the reflected light from #84 passed through the lens and hit the film, the white numbers sensitized the film a lot, and the black jersey reflected no light. So white numbers registered on the film and the black jersey did not. When we developed the film – by chemically oxidizing those silver salts that were sensitized by the light – the numbers became very black and the dark jersey, which reflected no light to the silver salts, came up clear and were washed away.

NOW LET’S ZOOM IN ON THIS PLAYER….

Film Photography

and shine some light through this “negative” to a piece of photographic paper. A lot of light will pass through the “white” (or clear) portion that is his jersey. But, because the numbers are black, they will block light from getting though to the paper, so….. when we develop the paper we get this:

Film Develompment

A “positive” rendition of the scene… a photographic print! Because light passed through the white part of his jersey, the final print renders it black…. as it should be.

Color photography, although too complicated to go into in detail here, looks similar:

A COLOR NEGATIVE OF BRETT FAVRE

Brett Favre

WILL PRINT UP LIKE THIS:

Brett Favre Photograph

Color slides (transparencies) happen because the film basically has a few layers of silver salts that act as a negative and, during the processing, re-exposes the positive layers, thus giving you a positive image.

HOT TIP OF THE DAY:

The numbers and brand name you see on the edge of developed film were put there by the film maker. If those letters and numbers are not solid black … the film was not developed properly. If the characters are lighter – grayish – the film was under-developed. And, if they are VERY black, the film was over-developed.

Now, if you have the past pages well understood and fixed in your mind, it is time to get to the advanced photography goodies.

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10 Responses to “Photographic Film”

  1. Although i have never and do not intend in the future to develop my own photographs i appreciate the clarity that has taught me about this subject.

  2. Hi!
    I need to learn more about taking good photos, both digital and with a Canon EO5 Rebel G11, to showcase my textile artwork. I have some trouble with getting good quality when I upload to my website although the same images might print out fine and turn out excellent on paper.

    I’m somewhat confused about pixel sizes, perhaps that’s in a later lesson. I uploaded some of my other images (landscapes, things) to sell on a website but they were rejected because of “Reason: Blurry: Image is not very crisp or is blurred when viewed at full
    size.” Also “Reason: Artifact Problems: Noise/Grain/Chromatic or other artifacts due to low light, blue or purple fringing, high ISO, over-sharpening or post processing techniques.”

    How do I correct these issues? I mostly let the camera autofocus when I take closeups and also when outside.

    Thank you for your great lessons!
    Katrina

  3. In our Digital Camera Lesson we talk a little about pixels. In our Exposure Control Lesson we talk about how to use shutter and aperture to control light. Noise/Grain issues occur when taking pictures in low light, your digital camera is compensating for the low light by increasing the ISO value of the digital sensor. When using your digital camera, make sure it’s set to take pictures at the highest quality setting and use more light. If you aren’t using a tripod, you should.

  4. I agree with Brian. So much clarity & I can definitely see how this will be useful knowledge.

  5. thankyou for making this easy to understand, have read about this subject from fuji book at work in photo lab and it wasnt as clear to understand.

  6. your site is awesome! I’ve taken pictures since I was very young (with a Minolta SRT101) and just recently got the bug back… my question is, any advice or suggestions on home b&w film developing ? the explanation of the b&w process is fantastic!

  7. …I just went to the next lesson, and answered my own question…lol!

  8. Just started photography and up until I found this site and your wee course I was flummoxed with most stuff, now its a lot clearer and I now know how film is developed.
    Thank You so so much.

  9. Nice website. I’m starting to tinker with a Canon Eos 500D. I hope to improve in using the manual mode to be more creative.

  10. Great explanation.
    But i believe that few words about the sensitivity (ISO and dimension of grains) are demanding.
    Best regards.

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