Basics one and two, How an image is made

On your blog, post the following:

Title- "How an image is formed"
1. List at least two things that are essential for photojournalism that the camera obscura could not do.

2. Explain what an emulsion is and how it forms an image.

3. (Challenge) Go to:http://electronics.howstuffworks.com/digital-camera.htm Scroll down to the section titled "a filmless camera" and read it carefully.
Answer the following:What do digital cameras and film (emulsion) cameras have in common in how they make an image, and how do they differ?