Magnification and Light Sources [154]

MAGNIFICATION AND LIGHT SOURCES

 Optical Magnifiers:

The 2-3 power range is useful for reading the fine print in catalogs, (Figure 1) but for stamps, 6-8 power is more useful.(Figure 2)  On the other hand, higher magnification is often a hindrance since the range of vision is restricted.

An optical microscope is reserved for very high power, but isn’t the easiest to use.(Figure 3)  I’ve often found that a lens from one of my old retired 35 mm SLR cameras is useful for higher magnification.  Going along with any lens, a light source is needed.  Today, magnifiers often come with a built-in light source.  Since some things require measurement, let’s add in a scale on  lens so we can measure directly. A few typical magnifiers are shown in Figure 4.  Some are simply magnifiers; others have added features.  A few of them were added to my menagerie because the predecessors are buried somewhere on the desktop (I think). And while we are at it, let’s have one so it fits in my shirt pocket.(Figure 5) The linen tester gets its name for the use in counting threads in linen cloth, but also works nicely with stamps.

Electronic Magnification:

  The optical magnifier is limited by the size of the glass.  This can be solved by adding another lens, but then it gets bigger and heavier. Changing the shape may help may aid, but often causes distortion. The electronic camera can come to our aid.  
When we take a picture, minute sensors each record a small piece of the picture. Enlarging these small pieces (called pixels) makes our picture larger, but eventually we reach a point where we have gotten all the information. If we make the number of sensors greater, we can enlarge it more.  This is called resolution. More sensors, the greater enlargement possible, but also the price increases.  If you recall earlier TV, you could see each pixel on the screen as a dot.  Today, with higher resolution TV’s, we can’t see the dots as readily, but they are there – just smaller.  Thus our camera, software, and computer combine to electronically enlarge pictures.  We can add in some of gee-whiz items, like measurement scales, and even ultraviolet light to our camera.  Do you absolutely need one?  No, but it does make some tasks easier.(Figure 6).  A good example is distinguishing Type I basic stamp on the 2d overprints from type II stamps. The type I (figure 7) has four lines between the King’s head and the frame while type II (Figure 8) has three.

Light:

Lets look at a related area – the light source itself. What we call light (Figure 9) is part of the electromagnetic spectrum.  Visible light is roughly4000 to 7000 Angstrom units.  bounded by ultraviolet light and infra-red light Although most people can’t see it directly, ultraviolet light is useful to collectors and will be discussed in a later article.

Visible light is a mixture of what we call color.  Have you ever noticed that different light bulbs produce different colored light.  The standard incandescent lightbulb gives an orange tint because the light comes from a heated tungsten filament. The purple light from streetlights comes from mercury vapor.  Some fluorescent tubes give a warm pink while others a cool blue depending on what chemicals are used. When we look at a stamp, what we are seeing is the incoming light reflected off the paper minus those incoming light frequencies absorbed by the ink thus our view is affected by the incoming light. This can be observed if you take a blank piece of white paper and look at it under different lights.  If the incoming light is red, then our sheet of white paper appears red since none are absorbed.  The Scott catalog recommend using the “…winter light from the north…” which is in short supply at 11 PM  (Except in far Northern Ireland in the summer).  The answer to this is a fluorescent bulb that produces a constant balanced color.  They are called Ott lamps, and, surprise, are readily available and reasonably priced at office supply stores.  You’ve probably seen them at shows where dealers often use them. Why?  Because they are “true” color” and produce a balanced spectrum.  (Figure 10).

This isn’t, by any means, the complete story on light, but hopefully it will answer a few questions for the collector.