Jan Hinsch wrote an excellent review article “About the Use of Digital Single Lens Reflex Cameras on Microscopes” in 2004 for the web journal Modern Microscopy, http://www.modernmicroscopy.com/main.asp?article=33&print=true. The purpose of this article is to demonstrate the capabilities of the new Olympus Evolt E-330 DSLR for use with older design microscopes to capture the full diagonal of an 18 mm field number eyepiece that is not high eyepoint. This camera can be fitted with OM mount film camera lenses using the Olympus MF-1 adapter. A key requirement I had before purchasing a DSLR was that critical focusing must be possible at the full resolution of the sensor. I asked the Olympus Precision Instruments Group whether Olympus would have a DSLR available with this capability, and learned from them that the new E-330 DSLR would allow a selected area to be displayed at full resolution from the main CMOS sensor for critical focusing. This 7.5 megapixel sensor measures 13 by 17 mm.

An earlier article in Microscopy Today, "Rediscovery of Darkfield Dispersion Staining while Building a Universal Student Microscope," noted that the darkfield inserts were made for Peter Cooke (MICA, Chicago, IL) to be used to teach high resolution dispersion staining in his advanced microscopy classes using Olympus BH2 microscopes and the Olympus 1.25 NA Abbe condenser. Peter has asked whether there is a better condenser design that will reduce the time and effort needed to switch between brightfield and darkfield.

Microscopists and scientific photographers sometimes find it desirable or necessary to record a larger field size than the lowest power objective can cover using brightfield illumination. This applies to the largest thin sections examined by biologists and geologists in transmitted light and the opaque, planar specimens examined by the materials scientist in reflected light. These needs were once well met by Leitz with their Panphot and Aristophot systems and to a lesser extent by Zeiss with their Ultraphot II.

My first universal student microscope, shown in Figure 1, began life as a Monolux microscope from the 1960rs. Its development into a universal student microscope began when my wife wanted a polarized light microscope with the ability to photograph microscopic crystals under a cover glass for their artistic value. My background as a metallurgist was with the reflected light metallurgical microscope, I have also designed and built vertical illuminators for brightfield illumination of complete metal log raphic specimens using a fiber optic light guide end as the light source with lens configurations giving an imaged field diaphragm and an illumination aperture diaphragm imaged in the aperture of the macro lens.

My home microscopy of lake water organisms with my two student microscopes lead to my active participation in Micscape Internet magazine available at the web site http://www.microscopy-uk/mag. An article in Micscape by Dave Walker, http://www.microscopy-uk.org.uk/mag/artian02/toptips8.html. played a critical role in my decision to purchase a Nikon Coolpix 995 for my home microscopy. Dave's article referenced a far more thorough article on fitting a consumer digital camera to older style microscopes: The New Microscopy by Peter Evennett, Proceedings RMS, Vol. 35 (4), Dec 2000.

Some may have read my previous articles in Microscopy Today and know that I am a strong proponent of digital imaging for photomicrographs and photomacrographs. I require that the digital images match the resolution and field size of traditional film images, with the 4X5 Polaroid film most commonly used in metallurgical laboratories where I worked before early retirement. My development of an affordable universal student microscope for home microscopy resulted in a need for color digital images that would meet my requirements at an affordable cost. This need was met by recording on 35 mm film with subsequent scanning of selected film images to a Kodak Master Photo CD. More recently I purchased a CanoScan FS2710 film scanner for digitizing my family's collection of slides and negatives for saving on CD's.

My previous article on digital imaging in the April 1997 issue of Microscopy Today noted the use of an Olympus Auto Bellows with a Kodak MegaPlus 1.6i/AB CCD camera for digital photomacrographs equivalent to 4 x 5 Polaroid prints with magnifications between 10X and 50X, The purpose of this article is to document the high resolution obtainable with the bellows system and the design modifications needed to eliminate the plastic dovetail inserts of the Olympus Auto Bellows, which are susceptible to delayed stress cracking when used with a heavier camera like the MegaPlus, Total failure of the dovetail inserts could cause costly damage to the lens and the camera.

The recent completion of a company-wide PC network system, supported by network servers intended to rapidly handle large data files from CAD systems, made implementation of digital imaging in the Corporate Materials Engineering laboratory of Case Corporation a wise investment. Laboratory reports in Microsoft Word with linked image files can be rapidly received through any of the networked PC's and are archived in the server system. The changeover from film imaging to digital imaging was very sudden. This change was accelerated by satisfied users, whose work was made easier and more productive, and satisfied customers within Case Corporation.

Industrial laboratories have traditionally used 4” x 5” (100 x 125 mm) photomicrographs. Polaroid 4” x 5” prints have largely replaced glass plate and sheet film contact prints in industrial laboratories. High resolution 2000 by 3000 pixel imaging systems should be able to match the resolution of the 4” x 5” photomicrographs, typically 6 cycles per mm at a magnification of 500 times N.A., with a significantly larger field size which better utilizes modern, wide field optics. CCD cameras with 1024x 1280 pixel sensor arrays should be able to essentially match Polaroid 4” x 5“ photomicrograph prints in field size and resolution.

My Inter/Micro-84 presentation and subsequent article in The Microscope dealt with optimizing diffraction limited depth of field in photomacrography and is referenced by Brian Bracegirdle in his “Scientific Photomacrography. My analysis was based upon the classical solution for the diffraction pattern image of a point light source, using the Rayleigh criterion of resolution. H. Lou Gibson's method of treating combined diffraction and geometric blurring away from the object focal plane was used. The calculations and the experimental results indicated that a final print resolution, for the object focal plane, of 7 lines/mm (.29 mm Airy disk) gives an optimum balance of depth of field and resolution. The 7 lines/mm criterion is equivalent to an Abbe criterion of total magnification equal to 440 times the numerical aperture. The 500 times numerical aperture Abbe criterion recommended for microscopists with very acute vision corresponds to a maximum resolution of 6 lines/mm in the final image.