RAW
If your camera has a setting that allows you to shoot in RAW mode, then set your camera to this setting. While pictures taken in RAW mode will be larger than those taken with a JPEG setting, RAW digital files retain more information than images that are saved as a JPEG images. After you have downloaded the raw images to your home computer, you can process them and save the edited pictures as JPEGs.
Aperture
The aperture refers to the size of the lens opening. When a lens is wide open it has a very shallow depth of field. With a shallow depth of field, the depth of the image that will appear in focus is very shallow. Using a smaller aperture, around f8 to f11, will increase the depth of field and allow for a small amount of error in camera focus.
Shutter Speed
Having your camera mounted on the tripod will help to eliminate as much camera shake as possible. This will be particularly important when it comes to setting your shutter speed. With a smaller aperture, which reduces the amount of light coming through the lens, you will need to use a longer shutter speed to achieve a proper exposure. When taking the picture of the old slide, take a test picture and check the exposure and make any adjustments to the shutter speed that needs to be made.
ISO and White Balance
Set the camera's white balance to match the type of light you are using to illuminate the white background. This is particularly important if you are not able to set your camera to shoot in RAW mode. By setting the camera to the correct white balance, you will reduce the amount of color correction editing you will have to complete in post production. ISO is the camera's sensitivity to light. While a higher ISO will allow you to use a faster shutter speed, you compromise image quality. Set your camera to the lowest ISO speed. The resulting picture will have minimal or no digital noise.