Scanning with Digital SLRs!

 
Left Image:
Canon EOS A2, Tokina 300mm ATX f-4, Fujicolor 100 Super HQ, 1/125 sec at f-5.6, aperture priority, Bogen tripod and ball head. Original negative of this magnificent Lynx was copied using a Canon EOS D30, Canon 35-80mm zoom, Kenko 35mm extension tube on ordinary light box.

Did you know your digital SLR is an excellent tool for scanning slides and negatives?  If you currently don’t own a film scanner,  you can make quality digital images from your  slides or negatives by copying them, using your digital SLR. 
You’ll need the following equipment:

1. A digital SLR

2. A close focusing lens such as 50mm or a 100mm macro, or any zoom that covers short telephoto range such as a 35-80mm or a 70-210mm with extension tube

3. Lens hood

4. Llight box. 

 This process is similar to making duplicate slides using film cameras. To make duplicates of original slide films as back -ups, professional photographers use sophisticated slide copiers to achieve best results.  The original slide is placed on the copier which has a light source built-in.  To control contrast, which is always a problem when making duplicates, filters are dialed in to increase or decrease contrast.  The camera is then mounted on a copy stand that looks like an enlarger baseboard with column.  The copier is placed under the camera.  This whole system is best for making duplicate slides with film cameras, but costly and inappropriate if you plan on copying a few slides and negatives occasionally. If you have a lot of slides and negatives, by all means purchase a good film scanner for the job, since quality film scanners produce much better results and are far easier to use than any other method. However, for occasional copying, by using simple equipment you may already own, quality digital duplicates can be made very easily without having to spend on a film scanner.

Here’s how it works.  As I mentioned earlier, you’ll need a light box.  Any light box that is made exclusively for viewing slides with correct color temperature will do just fine.  The light box is used as your light source and a flat surface for placing the original film.  The next step is to find a way to get close enough and bring the slide or negative into sharp focus.  In other words,  you’ll need to get to life-size distance or as close to it as possible.  Life-size means that the object’s size will be recorded on film exactly as in real life.  A coin, for instance, photographed at life- size, will be identical in size as in real life.  The easiest way to get to life- size is by using a macro lens.  Macro lenses can focus all the way to at least 1/2 life-size or full life-size without requiring any additional attachments. A 50mm macro lens, which is equivalent to about a 75mm lens in digital format, gives adequate working distance and coverage. 100mm macro lenses, which are equivalent to about 150mm in digital format, giving plenty of room to fill the whole frame. If you don’t own a macro lens, there is another way you can get to life-size. Use a short telephoto lens such as a 35-80mm zoom or a 50mm normal lens with extension tubes.

Extension tubes are inexpensive devices that are places between the camera and the lens in the same manner as teleconverters.  Tubes actually look like teleconverters without the glass. Tubes allow you closer focusing with any lens, but you lose infinity focus. In case of close-up photography or copying, we don’t really care about infinity. We are only concerned about how close we can get. How close you can get with extension tubes depends on the lens in use and the size of the extension tube.

In order to get to life-size, you must have exactly the same millimeter of extension as the lens in use. Check out this formula:

 Magnification=  Extension x Lens in millimeter

As you can see, 50 millimeter of extension is needed to reach life-size with a 50mm lens or 100 millimeter with 100mm lens.  It doesn’t matter if you are using a zoom lens or a single focal length lens.  Millimeter is millimeter. Macro lenses don’t require extension tubes. The already have the extension built right into them. A 28-80mm zoom that can only focus to about 1/4 life –size however, requires extension tubes for additional focusing distance. My favorite combination for copying slides and negatives into digital format is by using 35-80mm zoom and 25mm or 35mm extension tubes.  I’m not too concerned about getting exactly to life-size as I would have been if I were duplicating slides onto slide films.  Digital photography allows me to do cropping or enlargements later in the computer. With a 35-80mm zoom and tubes, I can get close enough and bring the slide or negative into focus by just turning the zoom ring. Best of all,  I don’t even have to use a tripod!  I attach a lens hood to the front of the lens and place the hood around the original slide or negative. The hood acts as support. This technique is not the best way to make duplicates. However, digital manipulation has made correction to the copy of the original very easy. Flaws can easily be corrected in Photoshop or similar photo editing software.

Now, lets take a look at the actual steps you need to take to copy slides and negatives.  

MAKING DUPLICATE SLIDES AND NEGATIVES STEP-BY-STEP PROCESS:

1.   Select your slide or negative and be sure to remove dust by using a blow brush.

2.   Slides and negatives should be cut and mounted inside slide mounts.

3.   Clean the light box. Make sure there is no dust or hair on the surface.  Even small dust particles will show up on the final image.

4.   Attach your macro lens or any non macro lens with extension tube. 

5.   Attach a lens hood to front of the lens.

6.   Focus on the Slide or negative. It is actually best not to go all the way to life-size.  Somewhere between 1/2 to life-size is a better approach.  You can get better corner sharpness of the original slide.  It doesn’t matter if the slide mount is included in the frame.  You can crop this part later in photo editing software such as Photoshop.

7.   Set the lens to  f-11 on aperture priority. 

8.   Set the camera to the slowest ISO possible. The shutter speed will be low but that shouldn’t matter since you’ll be pressing the camera down against  the lightbox with the lens hood acting as support.

9.   Bracket your shots 2 stops in 1/2 stop increments.

10.   Experiment with different white balance settings to see the result you like best.  I personally use auto white balance and correct color later in Photoshop.

11.   Use the maximum resolution your camera has to offer.

12.   To take the picture, make sure to press down on the lightbox to prevent the camera from moving.

13.   Press the shutter.  Release very gently.

 Once you finish copying, download the images to your computer.  Open Photoshop or other similar photo editing software you have.  Copies of slides are much easier to work with since you see a positive image on the screen.  The first thing you’ll need to do is to correct color, contrast, and exposure as well as hue and saturations.  You then need to crop the image.  Don’t just use the crop tool. Rather, use crop and select “front image” in Photoshop.  This will keep the exact size and resolution of the original file.  Finally, use unsharp mask to sharpen the image.  If the original slide or negative was sharp and you have done a good job copying the original, I would say 50% to 200% sharpening should be enough. 

Editing negative images is identical to slides, except you need to invert the image first to a positive recognizable image. Photoshop and other powerful image editing software provide a tool for inverting negatives or even slides (Image-adjustment-Invert). Once the negative is inverted,  it will have a bluish color cast.  You can quickly fix this to some degree by using auto color correction tool. You can then continue by using additional tools described earlier to further correct color, contrast, and any other corrections you feel is required. If you follow the whole process correctly, you can get good results without having to spend on expensive film scanners.  

 Recommended macro Lens

Sigma 180mm F3.5 EX IF HSM Macro Lens
This high performance tele-macro lens can focus from infinity to full 1:1 Life-size reproduction without accessories. At 1:1 reproduction the distance from subject to film plane is 18.1 inches, making this lens convenient for photographing subjects which are not easily approached, such as small animals or insects, etc. The apochromatic design and two SLD (Special Low Dispersion) glass elements, plus floating inner focus system effectively control Chromatic and Spherical Aberrations as well as Astigmatism, providing superb performance throughout the focusing range. The models for Sigma, Canon and Nikon AF cameras employ Sigma's HSM (Hyper Sonic Motor) for quiet, responsive AF function plus "full time" manual focus. A Focus Limiter switch aids in faster AF for closer or more distant subject situations, by restricting the movement of the focusing mechanism. The HSM model lenses can be used with Sigma's 1.4X EX teleconverter as a 252mm f/4.9 lens, with Sigma, Canon and Nikon AF cameras, providing AF function from infinity to about 47 inches. At closer distances, the lens automatically switches to manual focus. (The models for Minolta and Pentax cameras will be manual focus with the 1.4X EX teleconverter.) This lens can also be used with Sigma's 2X EX teleconverter as a 360mm f/7 lens, for manual focus in all cases.