Articles in “Micscape” web magazine for amateur microscopists and a Royal Microscopical Society Proceedings article by Peter Evennett recommended in one of the “Micscape” articles, demonstrated how the Nikon Coolpix 990 was the best-suited consumer digital camera for use with microscopes.  Its moderate aperture, internal zooming and focusing lens was found by others to permit recording the full field of view of a 10X eyepiece provided that the eyepiece or adapter has a high enough eyepoint.  My prior publication in The Microscope (Clarke, T. M. “Digital Imaging in the Materials Engineering Laboratory”; The Microscope 1998, Vol. 46 No. 2, 85-100) on digital imaging in the materials engineering laboratory with a Kodak MegaPlus scientific-grade digital camera, has a composite image demonstrating how using a non-compensating relay lens in place of a compensating Kpl eyepiece in a Zeiss Universal can drastically degrade image quality. This is by chromatic difference of magnification (CDM), which is cancelled by the matching compensating eyepiece.  [A description of this problem, and its origin may be found on p.11 of John Delly’s Kodak publication, Photography Through The Microscope (1)]. Part of this image is reprinted in my “Micscape” article on the effects of CDM.  The “Micscape” articles led to my purchase of a later model Coolpix 995 for my modified LOMO and Monolux microscopes.  My article “Fitting a Student Microscope with a Consumer Digital Camera” (see note 1) in Microscopy Today (May/June 2002,15-18) demonstrates the Coolpix camera mount I made for these microscopes.  A 10X 20-mm field number high eyepoint eyepiece was purchased from Mark Simmons, a maker of digital camera adapters, for my Monolux using Edmund Scientific objectives not requiring a compensating eyepiece.  This eyepiece has an eyepoint of about 23-mm, which I found adequate to prevent vignetting without having to nest the eyepiece into the filter threads of the Coolpix lens.  I knew that my LOMO Edupointer eyepiece (no longer in production) had only an 18-mm eyepoint and was the highest-eyepoint compensating eyepiece for the LOMO objectives.  This lower eyepoint distance required the eyepiece to be nested inside the filter threads in order to avoid vignetting.

My first use of the Coolpix 995 with an Olympus BH2 was to help Peter Cooke ( of MICA, Chicago) record images of high-resolution dispersion staining with the Olympus 40X objective.  This photography was done using the Coolpix 995 mounted in a salvaged enlarger stand so the 10X WHK eyepiece in the trinocular photo port was almost in contact with the end of the filter threads of the Coolpix lens.  Vignetting could not be prevented, even though the camera aperture was manually set to the smallest f/number to minimize vignetting caused by the camera iris, so the resulting images were cropped.  The camera lens was not zoomed to exclude the vignetted outer zone because I know this could introduce image artifacts from residual tool marks on the mold surface subsequently replicated on a molded plastic aspherical lens element in the Coolpix lens.  The experience helping Peter led me to suspect that the vignetting could be reduced with an 8X WHK eyepiece because of its smaller angular field.  Chuck Zona  of McCrone Microscopes and Accessories subsequently provided me with an 8X WHK eyepiece to determine whether a suitable adapter could be made for the BH2 using this eyepiece. This took place after sharing e-mails with him from an environmental microscopist.  This microscopist was upset over the poor image quality of his digital images taken with a BH2 microscope and Coolpix 995 using a non-compensating adapter purchased on a recommendation from one of the teachers of digital microscopy.   The making of the BH2adapter with the WHK eyepiece and its subsequent modifications to fit a Coolpix 990 are the subject of this article, with emphasis on the lathe-threading process used for this adapter.  The Coolpix 4500 was the last in the series of swivel body Coolpix cameras using the lens design making them uniquely well suited for use with a high eyepoint eyepiece.  These cameras are no longer in production, but there should be a good supply of used and refurbished 990, 995 and 4500 models for those wanting low cost, high resolution digital imaging with a BH2 microscope.