Getting Started with Film Scanning - Part 2
In a previous post, we took a look at the main scanner types available for you to choose from in order to digitize your film captures if you plan on sharing them online for example, or even just running them through a photo-editing software for further manipulation. Today, we'll continue our journey.
As we have seen, you can basically choose one of three scanner types: a film scanner, a regular flat-bed scanner, and if you're going to be needing it for commercial use to generate high-end scans, a drum scanner. There are of course more types on the market these days, but these are the main ones. We took a look at the most important scanner specifications to keep an eye out for when out shopping for your a new device.
So you went out and brought home your new scanner, what next? In today's post, we will have a detailed look at how to go about making digital copies of your film captures, whether that's prints or negatives.
The first thing to do after you connect your scanner to your computer is to install the software that comes on a CD with it. This is called the scanner driver and comes either as a standalone application or a plug-in that acts as an interface between your scanner and your photo-editing software. If you are working with the plug-in version, you will have to call up the software from inside your photo-editing program (like the File > Import command in Adobe Photoshop).
Whichever the case may be, scanner software comes with some features and options that give you control over how the final scanned result will turn out. These options include image size, resolution, color space and format settings. Other settings may include brightness and contrast adjustments, color cast elimination, color restoration for faded print images, and dust and scratch removal among others.
Choosing the Best Resolution
The resolution you will want to scan your images at really depends on what you will be using those scans for. You might want to scan your images to share them on the web, you might want to make photographic prints after manipulating them, or you might want to use them for publishing in books or magazines, so it all depends on the resolution of the image in the final state.
Also the type of image scanned plays a role in determining the scanning resolution. For example, scanning typical 35mm (6x4 inch) color prints will not benefit from a resolution higher than 300ppi because these positives are of a lesser quality than the original film negatives to begin with, so scanning at a higher resolution will only leave you with a larger file size, but not more image details. Also the positive image is larger than the film negative, so it needs a lower scanning resolution to yield the same digital file size.
Film was designed in such a way that it can handle enlargement without losing details to begin with. That is why it is always better to scan your original negatives rather than prints to achieve better quality and more detail.
In the end, the rule is simple. The scanning resolution determines the size (dimensions) of the digital image file which is measured in pixels. So if you scan a 6x4 inch positive print at 300 PPI (pixels per inch), you end up with a digital image of 1800x1200 pixels (6x300=1800 and 4x300=1200). So you need to know what the dimensions of your digital image should be for a particular purpose.
A higher resolution creates a larger image. A lower resolution creates a smaller image. Also, depending on the above rule, it is obvious that you need a lower resolution to scan a larger image print to get the same file size as you would for a film negative or a smaller print. Your scanner software usually calculates and displays the final image size for you depending on the original image size and the chosen scanning resolution.
If, however, you intend to later print out your digital scan, then your scanning resolution will be determined by the size of the final print you wish to have and the printing resolution you will be using. This means that if you are going to be printing a 6x4 at 300 dpi then you can scan at 300 ppi if that the original image size is 6x4 inches as well.
If the original scanned image is 3x2 inches for example, you will need to scan at 600 dpi to get your 1800x1200 pixels (3x600=1800 and 2x600=1200) which will later give a 6x4 inches final print at 300 dpi (1800 / 300 = 6 and 1200 / 300 = 4). So to print at the same original size, scan at the same printing resolution. To print at twice the original size, scan at double the printing resolution. And to print at half the original size, scan at half the printing resolution.
But what happens if you are scanning film negatives? Film negatives need higher scanning resolutions particularly because they are smaller in size than their positive counter parts. Of course scanning large sheet film needs much less enlargement, so you don't need to go over the top with your scanning resolution. The below image shows the difference in size between a typical 35mm positive printout and a negative film strip of 4 frames:
A typical 35mm negative film frame is 1.4 x 0.9 inches, scanned at 2700 ppi yields a file size of 3780x2430 pixels (1.4 x 2700 = 3780 and 0.9 x 2700 = 2430). Later printing this file at 300 dpi will give an image size of 12.6 x 8.1 inches (3780 / 300 = 12.6 and 2430 / 300 = 8.1), which is 9 times larger than the original film negative scanned (12.6 / 1.4 = 9 and 8.1 / 0.9 = 9).
This is known as the enlargement factor and it also equals the scanning resolution / the printing resolution (2700 / 300 = 9). Since the origin of the scan is a film negative, then a printout 9 times the original size will have good quality as film was made to allow for great enlargement while preserving the quality and details of the image.
To make things simple, some scanner software does provide you with predefined scanning resolution profiles to choose from depending on your original image size and the intended output (online sharing, laser printing, photo quality printing, and so on). This will give you peace of mind as you can just choose the option that best suits your situation.
Analog vs. Digital
Film images have continuous tones where it is difficult to tell where one tone ends and the second begins. This is called a continuous tonal gradation.
If the tonal gradation between successive mid-tone values is smooth where no areas have absent values, the tonal separation would be continuous and you would have an image with smooth transitions where brightness appears consistent and uninterrupted from one value to the next.
The very act of digitizing your images means turning those continuous tones to digital values where the end result is a set of specific colors and tones and the tonal gradation is "stepped."
Below is part of an image that is zoomed in at 400%, which shows how digitized pictures consist of pixels of specific color values. As you can see, the transition in tones is stepped rather than continuous, and you easily see what color each pixel holds. The color set shows a finite number of colors that are contained in the digital image.
Before you scan a negative film or positive image, you need to clean its surface from any dust or marks, as these will be visible on the final digital copy. Also, if you're using a flat bed scanner, make sure you clean its glass plate from any dust. For this, you can use a soft cloth or an air blower specifically designed for this purpose.
If you are scanning negative film, remember to place the side with the emulsion facing the scanner sensor (also check with your particular manual to make sure you have the film strip in the correct way before inserting).
If you are scanning images that were printed out on thin paper, any writings on the other side might be visible in the scanned file. You can try placing a black card over the image to avoid the content on the rear side from appearing in the digital file, but it will make your photo appear slightly darker. However, you can adjust the brightness either before you make the scan through the scanner settings (some scanner applications allow you to adjust brightness, contrast and the overall tonal scale of your scans), or later in post processing.
Some flatbed scanners are modified in order to make scans of negative film in addition to print images. If you have one of those, or if you are using a dedicated film scanner, it is better to scan your film negatives rather than the positives. This is because positive images are lower in quality than the film negatives as the dynamic range of paper is smaller than that of film. Also color balance and image sharpness can be different on the print than that on film.
If using a film scanner, remember that you need to set the film type you are scanning: color negatives, color positives, or black and white. Some scanners will even allow you to set the film brand. These scanners have specific profiles that are used with each film brand to make up for the different color characteristics of each emulsion type. Some also allow you to set your own custom profiles to further tune the end results to your liking.
If you are someone who enjoys shooting film, there probably will come a time when you will want to upload your photos online, publish them in books and magazines, or just print them after digital manipulation.
If you stick to the basic ideas covered in this article, you should have a pleasurable experience with your scanner. Just be patient, and handle your film with care.