I couldn't wait for Santa (I've been a naughty boy anyway) and bought myself a new camera, this time a digital SLR, the new Olympus E-500. Besides the 2 lenses that come with the camera as a kit, I also got a Zuiko 35 mm macro lens. Here is my meager review of the macro lens with some test shots I have taken with it.
My test object was a stage micrometer (Edmund Optics NT36-121), which is an etching of a millimeter (1000 μm) divided into 10 μm*. The picture below shows a photograph of the micrometer taken thru an Olympus SZ60 stereomicroscope. The 10-μm lines are clearly resolved.
Below is a photograph of the same using the E-500 with the 35 mm macro lens at its highest (or almost highest) magnification. Admittedly, the micrometer is not a good photographic subject, because the etching is very faint and, therefore lacks contrast. The photo on the left (A) is the original, while the one on the right (B) is after I increased its brightness and contrast in Photoshop (I did not change the sharpness).
The macro lens can't resolve the lines 10 μm apart; the closest lines it can resolve are about 50 μm apart. That is not bad at all when we realize that this is not a microscope. And I think the image quality is pretty good for a camera lens at such a high magnification.
The alternating blue and red lines visible in the background of Fig. B are known as Newton's rings. They are not an artifact of the camera, but are formed on the micrometer itself. Newton's rings are interference patterns created when 2 glass surfaces are pressed against each other (the micrometer is on a microscope slide under a thin cover glass).
When taking such highly magnified pictures the camera must be on a tripod or some other support. Otherwise, no matter how steady your hands are, the image will be blurred, because even the movements that may be imperceptible to you are magnified by the lens. This makes it somewhat impractical to use the camera for taking extreme close-ups in the field unless a tripod is available and the thing you intend to photograph is stationary. The picture below shows the set-up I used to photograph the micrometer.
A: homemade copy stand; B: E-500 with macro lens; C: spirit level; D: camera remote; E: rack & pinion mechanism from an old microscope used for fine focus; F: glass plate to hold transparent objects to be copied (negative, slide, etc.); G: very heavy, shot filled base; H: light source (originally for HP scanner shown on the left); I: screw into the camera's tripod socket (it all depends on that screw!).
I use the spirit level to assure that the camera and the object that is being photographed are both horizontal. Also, the shutter should be released with a remote especially if the shutter speed is slow. An additional potential source of vibrations is the movement of the mirror inside the camera, but that is harder to deal with.
I will review the camera itself on another post.
*This micrometer is used mainly to calibrate microscope eyepiece reticles. It would be impractical to use for direct measurements.