The Exposure

Printing is both a skill and a highly creative activity. The print is the climax in the long chain of events that began when the photographer first visualized the picture. For many photographers, making a fine print is one of the most challenging and satisfying aspects of their hobby or work. A print is made by passing light through a negative onto sensitive paper. The paper is white when unexposed and darkens the more it is exposed to light.
The darkest parts of the negative let pass the least amount of light, so the paper remains bright in those areas. Inversely the transparent parts of the negative let pass more light, so the paper darkens in those areas.

Sectional View Of An Enlarger

The light from the bulb passes two lenses: First it is focused on the negative in the insertion then it is focused on the objective.

What Is A Contact Print?

A contact print is one made by placing the negative in direct contact with the printing paper. Contact prints can be made with a printing frame, which resembles a picture frame with glass. The negative is placed on the photo paper with its emulsion side up, and the printing frame is placed on the negative. The contact print obviously has the same size as the negatives.
It's very useful to keep an overview of all your negatives.. .

How Long Must I Expose The Photo Paper?

Of course the time the exposure takes depends of the grade of the paper/filter you use and of the size of your photo paper. The most usual way to find out how long you have to expose your photo paper is to make test-strips as you see on the picture. A black sheet of paper is used to cover a big part of the paper and let the light just exposure a small strip of the paper for some seconds. Then you move the paper so the strip exposed becomes wider and you expose a second time and so on. Then you develop that picture. In daylight you can then easily determine which stripe has the right brightness.

How Can I Influence The Contrast Of A Picture?

photo papers
Several papers that produce pictures of different contrast

filters
Today it's usual to use filters to regulate the contrast of the picture.
00 (yellow) means the lowest contrast, 5 (magenta) the highest.

Grades of contrast:
hard, medium and soft

Contrast is a fundamental characteristic of printing papers. It refers to the density range - the difference between the whitest white and the blackest black - that the paper can supply and the number of distinct shades of gray that it can produce between the two extremes. A low-contrast paper can produce a relatively large number of these intermediate shades and can provide the best print from a negative with strong contrasts, i.e. extremely light and extremely dark areas. A high-contrast paper has a smaller scale of intermediate shades.
Paper contrast is designated by grade from 0 to 5, though not all papers are available in all grades. No. 0 grade paper is the lowest contrast, or softest. No. 5 grade paper is the highest contrast, or hardest.
There are also variable-contrast papers whose contrast can be regulated by using special filters. Such filters offer an advantage because they eliminate the need to stock several grades of paper.

Our example show three different grades of contrast:
The first image has a hard contrast - filter No. 5.
The middle one has a medium contrast - filter No. 2.
The third image has a very soft contrast - filter No. 0.