Consider Pixels
Photographs are made up of tiny dots of color, called pixels. When you enlarge a photo, those pixels may become more visible, creating a grainy looking enlargement. Picture Correct, a website that offers information about altering your photos, recommends sticking to 200 to 300 pixels per inch for the best enlarged photo quality.
Use the Right Lens
Most enlargers allow the use of a variety of lenses, depending on the size of the enlargement you want to make. These lenses change the amount of light that moves through your enlarger, which is how you make the photo develop larger. Following the directions for your enlarger is the best way to create the most high quality enlargements as the recommendations differ among brands.
Eliminate Outside Light
Most enlargers were designed for use in photo developing dark rooms, which necessitates the elimination of light produced from outside your work area. If you don't have a darkroom, modify a bathroom or closet that you can stand in with the door closed as an alternative. Keeping outside light away from your enlargements will produce finished copies that are identical to the original photo rather than being too light in areas. Darkroom materials are available at photo supply stores, allowing you to set up your space for using a photo enlarger.
Try Computer Software
With the rise of digital photography, many computer software programs have been designed to create high quality photo enlargements right on your home computer. Some computers are sold with photo software, but creating the type or size of enlargements you want may require the purchase of additional programs that are downloaded to your computer and may work with current software. These programs allow to you use more pixelated photos to make enlargements from digital camera photo cards or by scanning and printing photos from prints or negatives. They also manage and enhance the color and image of the photo when it is enlarged and can be used to edit the photo at the same time. Many photo supply stores and office equipment stores offer photo software or it may be purchased through your computer's manufacturer.