click image to enlarge (74K) Figure 1 click image to enlarge (123K) Figure 2

My initial tests of the Olympus 8X WHK eyepiece were with the Coolpix 995 mounted separately on my macro stand as shown in Figure 1.  My procedure is to first focus through the high eyepoint eyepiece visually. Then I slide the microscope under the camera for digital imaging as shown in Figure 2, with the eyepiece just clearing the filter threads on the camera lens.  I set the camera focus at infinity because the autofocus does work reliably with the camera used on a microscope. I manually set the camera aperture to the smallest f/number to minimize vignetting by the camera iris. I used this procedure with the 8X WHK eyepiece and found that there was a small amount of vignetting at the edge of the visual field.  This meant that the eyepiece would have to be nested inside the filter threads to eliminate the vignetting.  This step was also necessary with the adapter I had previously made for my LOMO Biolam microscope.  Fortunately the eye-shield on the WHK eyepiece is easily removed as shown in Figure 3.  The end diameter of the eyepiece is now small enough to nest inside the Coolpix lens threads.  My preference in adapter design is to attach the adapters to the tripod-mounting hole in the camera base instead of directly to the filter threads.  The step in diameters with the eye-shield removed made this design quite easily done.  This was not the case for the adapter I made at about the same time for a Zeiss Universal microscope.  The Zeiss compensating eyepiece had to be nested inside the 28-mm filter threads of the Coolpix lens to eliminate vignetting, but the cover cap on the end of this eyepiece was already 28-mm in diameter.  I had no choice but to cut threads into the cover cap for direct mounting to the Coolpix lens. The mechanical cable release was built into a separate base, which attaches to the tripod-mounting hole in the camera base as shown in Figure 4.

click image to enlarge (92K) Figure 3

click image to enlarge (266K) Figure 4

The design chosen for the BH2 adapter is similar to that used for the LOMO Biolam and shown in the Microscopy Today article.   The major change in design was to thread the end of the bushing for the eyepiece and the mating flat base instead of attaching to the flat base with screws through a flange on the end of the bushing.  Another change was to properly locate the shaft for the cable release so there is no interference with access to the DC power cable port of the camera.  The first adapter I made had to have a notch cut into the side of this shaft to clear the power cable.  The bushing has an internal shoulder to locate the end of the eyepiece 1-mm from the glass face of the Coolpix lens.  The other end of the bushing fits over the right eyepiece tube of the BH2 and is locked with two nylon thumbscrews as shown in Figure 5.  This initial design fits my Coolpix 995 shown in Figure 6.  A Coolpix 990 camera was loaned to me to determine whether it would also fit the adapter.  It did not because the lens location was moved off the centerline of the camera base in the transition from the 990 to the subsequent 995 model.  The adapter was modified to fit both camera models.

click image to enlarge (73K) Figure 5

click image to enlarge (171K) Figure 6

click image to enlarge (280K) Figure 7

click image to enlarge (434K) Figure 8

   This was done by greatly enlarging the hole for the tripod mounting screw. The camera base is first squared up by rotating the camera about its lens extension, which fits into the end of the bushing in the base as shown in Figure 7. A round-headed ¼”-20 screw to the tripod mounting hole in the camera base is now used along with a large-diameter fender washer spanning the gaps around the hole when the screw is tightened.  The #6-32 screw mounting the cable release arm to the shaft now passes through a slot in the arm so the cable release can be centered over the shutter release of either the 990 or 995 camera. Figure 8 shows the 990 mounted in the adapter.  I have since learned that the location of the tripod hole has been relocated in the change from the 995 to the 4500, the final camera model in this series.  The BH2 adapter would probably fit the 4500 with an additional hole added through the base to mate with the relocated tripod hole.  The real performance test for the BH2 adapter came at the Inter/Micro 2003 McCrone Microscopes and Accessories exhibit, where the adapter was mounted with my Coolpix 995 on an Olympus microscope using 160-mm tube length objectives.  The photomicrographs in Figures 9 and 10 were taken of fiber samples.  The 20 mm field number (diameter of opening in eyepiece diaphragm) stop in the adapter eyepiece shows in the upper corners of Figure 9, which demonstrates no vignetting or ring artifacts from the camera lens. Vignetting may occur if the camera aperture is not manually set to the smallest f/number. The image of the edge of the stop has an orange color fringe characteristic of a compensating eyepiece.  Note that Figure 10 was taken with the camera lens zoomed just enough to put the field stop outside the field recorded.

click image to enlarge (84K) Figure 9

click image to enlarge (271K) Figure 10