Mini-FAQ Macro Photography, Frugal, mostly Digital

Macro Photography Using a Flatbed Computer Scanner

What happens when you scan a 3-dimensional object on an ordinary flatbed computer scanner? Often the results are quite remarkable, considering these scanners were designed for flat subjects. Even a low end 300dpi scanner can give usable results at 2X - 3X magnification.

Here are some tricks & tips I've collected:

Best scanners for 3-D objects.
The design of the scanner's optical sensor determines how far from the flatbed the scanner can focus. For scanning 3 dimensional objects, you will want a scanner with a CCD sensor. These are the thicker scanners with a fluorescent or "cold cathode" lamp as the internal light source. Scanners with CCD sensors will have a depth of focus of between 10 and 100 mm.
Some of the newer scanners use a CIS sensor. These are the thin ones that use LED's as their light sources. Scanners with a CIS sensor have a depth of focus of only a few mm, so they aren't very good for 3D objects.
A few scanners were marketed with 3-D objects in mind:
-Microtek ScanMaker X6 EPP
-Artec AM12S, AM 2400-U Pro
-Epson Expression 836XL
-3D Pro Scanner
-Memtek Memorex SCF 9360P 3D
Protect the scanner's glass top. For hard or messy samples, look around for some cheap, transparent sheets. Some ideas: sheet protectors, transparency sheets, plastic wrapping from consumer products. Real thin materials such as Glad Wrap (tm) tend to wrinkle, leaving white creases on the image.
Image format. If you're going to edit the images, save them in a uncompressed format such as TIF. If you use a format with a lossy compression such as JPG, each time you save an edited file it will suffer degradation due to the way the file format is compressed. It is best to do all your editing in an uncompressed format, and then convert the final product to JPG if you want to reduce the size of the image file.
Workarounds for lack of lighting control . Some ideas:
-Make a light tent such a " Don's 3 cent slide scanning adapter".
-Rotate the sample. The internal light source is directional.
-Use an external light source such as a light box for transparencies or a fiber optic lamp.
"Optical Resolution" is an important number. Some scanners will list optical resolutions like "300dpi X 600dpi"; in such cases the larger number is closer to fiction than being of any significance.
Will a scanner operate upside down? There are many 3 dimensional objects that would be easier to scan if the scanner were mounted upside down. Given that scanners have to be designed to withstand shipping hazards, I suspect that most would function fine in an inverted position. One guy tried this with a cheap Vivitar 300 DPI scanner and didn't run into any problems. The cheap Mustek 300 DPI scanner that I own also works fine in an inverted position, although I did notice that the ribbon cable that runs to the scan head rubs slightly against the glass flatbed when a scan is made in the inverted position. It's suppose this could cause a problem after extended use.

How to Compare Scanners

I came up with this cheap & simple test sample you can use to compare scanners. It consists of some pennies held in a corrugated cardboard holder. There are slits in the cardboard at 10 mm intervals to stick the bottom of the pennies in. If your scanner will focus out further, pick some other interval like 20 or 30 mm. If you live outside the US, any copper alloy coin in unworn condition and about 19 mm diameter will do.

The images on the right were taken with my Mustek 600 III EP PLUS (300 dpi optical resolution). The image has been resized so that the coins should be about full size (19mm diameter). The date area of each coin has been inserted at 300 dpi. The coin at 20 mm is starting to lose focus, but is still pretty good at 1X, The coin at 30 mm is both noticeably out of focus and washed out due to nonuniform lighting. Click here for the full 300 dpi version.

If you find a cheap scanner with remarkable 3-D results, I'd like to hear about it.

Adding Macro Capability to Ordinary Digital Cameras

A few consumer digicams have filter threads which allow conventional close up lenses to be used with a filter ring adapter. For other models, several approaches are possible: Using tripod threads as a hard point, friction fit adapters, and adapters held on by Velcro.

See Rules of thumb for adding additional lenses in front of camera

Macro Mode with Digicams - supplementary lenses
Friction fit lens adapter for DC2xx
BugEyeDigital - lens, accessories
Friction Fit Adapters
Micro/Macroscope Adapters
Adapter tubes are commercially available for just about anything. Adapters have also been cobbled up using items like PVC pipe and various things bolted to tripod threads.
Other
- Adapters for cp950
- Attaching a Monocular to the Epson PhotoPC 600
  Conventional Macro Photography
  Links
  Rules of thumb for adding additional lenses in front of camera
  
  Lenses are usually rated in one of three ways:
  Focal length is the distance from a lens where the image of a light source at infinity is brought into focus. If you learned to start a fire using the sun & a magnifying glass, the distance between the lens and the spot that you were trying to light was the focal length.
  Diopters is the unit of measurement used in eye glass prescriptions and the add on lenses used in photography.
  Diopters=(1000)/(focal length in mm)
  For example, a four diopter lens has a focal length of 250mm.
  The "power" of eye loupes & magnifying glasses are usually given in an "X"number
  Focal length=(250mm)/("X" number)
  For example a 5X eye loupe has a focal length of about 50mm.
  Lenses sold to be used as add on lens for cameras are usually labeled in diopters, and typically come in sets that match the threads used on lens filters. They are made to screw together so they can be stacked. When stacked together the diopter numbers add, for example, if a +4 and a +2 lenses are screwed together, they make a +6 diopter assembly.
  Rules of thumb:
  - The add on lens should be as close as practical to the cameras lens. Make sure they don't touch! It's easy to damage lenses by letting them come into contact with each other.
  - When stacking lenses put the strongest lens closest to the camera lens. This is to minimize distortion.
  - Add on lenses come in different qualities, an expensive corrected multi-element close-up lens is a lot better than a magnifying glass stuck on a filter thread.
  - Each additional lens that you add will degrade the image.
  - On cameras without a shutter release cable, some ideas to reduce vibration problems are: Use the timer, use computer control of shutter, cobble up an add on shutter release.
  - Prevent stray light from getting to the camera lens.
    
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    Copyright © 2004 by Stephen M. Powell.

Mini-FAQ Macro Photography, Frugal, mostly Digital

Macro Photography Using a Flatbed Computer Scanner

How to Compare Scanners

3-D Scanning Links

Adding Macro Capability to Ordinary Digital Cameras

Micro/Macroscope Adapters

Other

Conventional Macro Photography

Links

Rules of thumb for adding additional lenses in front of camera