This page describes the custom adapters made to fit a variety of cameras, microscopes, and medical instruments, for most of these adapters, they are $85 to $175, depending on the complexity. Old and new optical instruments are thereby fitted into the modern age of digital imaging. Besides the mechanical attachment, these adapters apply one of several optical principles to couple the camera to the microscope, including Afocal, through the normal eyepiece to inexpensive small-format digital cameras; Focal, from a photoport to lensless digital SLR cameras and Afocal, through a custom photo-eyepiece for large-lensed digital cameras. The first dimensional step is to turn down the cylinder, leaving a raised ridge of 37 mm diameter, ready to take on the outside threads. We chose to thread a length of 5 mm, which was about twice the length of the inside threads on the camera turret. Using the threading bit to turn the smooth diameter makes it easy to leave 60 degree bevels on all the stepped edges.

We were happy to find that the 0.75 mm metric thread pitch is available on the minilathe using the standard set of change gears. They are photos showing the work progressing on an aluminum billet that was made as a casting experiment, and the casting flaws show up as dark spots or flecks. For later versions, we have been using aerospace grade aluminum stock. Next we mounted the tailpiece onto the lathe with a drill chuck and 1/2-inch drill bit, and bored a hole into the center of the piece. With that 0.500 inch starter hole drilled, we were ready to start boring out the 1.138 inch inside diameter that would receive the microscope eyepiece. For this we used carbide boring bar bits that reached the 1″ depth of the finished part. Making the boring bar tool holder is the subject of another of my project descriptions. After boring the hole a few thousandths oversize, we had a close fit of the adapter to the eyepiece. We finished the part by cutting it from the cylinder using a parting tool. We cut a length that maximized the fitted depth, but still let the camera lens come to rest on the eyepiece. They are also photo showing the finished adapter. . An old Bausch and Lomb inspection microscope was tested and had been constructed a adapter on its own too. This US-manufactured item isn’t made any more, but when new they sold for about $2000. The optics are superb, providing a wide, flat field at a variety of zoom magnifications from 7x to 30x. Today, you can find them used on eBay for perhaps $500 or less, or you can buy a similar imported item for about that price new. The turrets of the binocular eyepieces have the virtue of being smooth, even aluminum cylinders. This allows a simple cylindrical adapter to nest on top of the eyepiece. This is the camera mounted on the microscope eyepiece. The adapter aligns and rigidly fixes the camera to the microscope. The camera lens protrudes in such a way as to touch the eyepiece, so we should apply a bit of vinyl tape as a cushion, or perhaps machine a spacer ring to insert as a standoff. We may add winged setscrews in the future to lock the camera on the eyepiece. This shows the camera turned on, with the camera display imaging the microscope’s magnified view of a coin. The optical system of this camera is well-matched to the exit pupil of this microscope. By adjusting the camera zoom one can either get a vignetted photo of the full field of the microscope, or a full-framed photo of the center region of the microscope view. Both modes are desirable for various purposes. The photo below shows the full-frame mode. This is a portion, at full resolution, of a photo taken by the Sony camera in the above setup. The object shown is a Lincoln penny, of which you are seeing part of Lincoln’s face. We measured the features shown with calipers, giving a true height of the representation as 0.070 in. The digital image is 526 pixels high. Thus the system resolves about 7500 pixels/inch, which is 7.5 pixels/thousandth-inch, 130 microinches/pixel, or 3.4 microns/pixel. If we assume your display renders 96 pixels/inch, then the effective magnification is about 78x or 526 pixels / 96 pixels/in / 0.070 in. The camera resolves 1472 x 1104 pixels not much by today’s standards, so the camera and microscope can photograph a physical area of about 0.2 by 0.15 true inches at this level of detail; the full field to the eye view in the microscope is about a 0.25 inch diameter circle. The microscope field zooms from about 1 inch at 7x magnification, to 1/4 inch at 30x. This is an amazing quality of result given that this camera sells for under $200, and the microscope sells used for about $500. Such a system would have cost many $1000s, and required costly film processing, not many years ago. We don’t know the resolution limits of the microscope optics, but they’re probably better than what the Sony DSC-S30 camera is resolving in this setup. If that is true, then a higher-resolution camera would resolve more detail. We have a much better digital camera now, but it uses a large-aperture lens that isn’t as well-matched to the microscope aperture, resulting in a severe vignette in the image. As a general optical design principle, one would want a small camera lens for this kind of behind-the-eyepiece microscopy. With camera lenses, bigger is usually better, since you can gather more light. But digital cameras can and typically do have very small, but nevertheless high-quality, lens systems, because the CCD electronic imaging devices are so much smaller than film formats. The light available is determined by the microscope optics, not the camera. Many digital cameras today seem to be using imaging chips and lenses that are very close to the human eye in physical scale. This is a wonderful thing for those wanting to adapt the cameras to microscopes, because no optical adapters such as a negative relay lens are needed, just mechanical arrangements. The pupil of the human eye may be assume to be about 4 to 5 mm in diameter when viewing microscope images. A good microscope will provide an exit pupil of similar diameter, and the camera lens should match this as well. Not so wonderful for the would-be photomicrographer is the trend away from putting filter mount threads on the lens turrets, even on the more expensive consumer models; later versions of my Sony DSC-S30 have a telescoping lens contraption that regrettably features no thread mount. If you’re looking to buy a digital camera with hopes of photomicrography, look for one with a fixed, threaded turret, with the inside thread diameter significantly larger than the microscope eyepiece you hope to use. Even if your camera has an extending/retracting lens turret, you may find an optional adapter tube that provides both room for the turret and filter threads for a further adapter. As a last resort, one can fit a sleeve machined just larger than the turret, with one or more screws for clamping to the turret itself. The original microscopy experiments above were done in 2002. In 2004, I repeated them with the same microscope, but using a higher-resolution camera like the Sony DSC-F707, 2560 x 1920 resolution = 5 megapixels and an Edmund Scientific Co. resolution test target gratings from 5 lines/mm to 200 lines/mm. This apparatus proved a resolution of 160 lines/mm or 4000 lines/inch, or equivalently to 8000 pixels/inch or 3 microns/pixel. The photograph shows a contrast enhancement of the 160 lines/mm grating. This is about the same resolution achieved directly viewing into the microscope eyepiece with the naked eye, and is the essential resolution limit imposed by the inspection microscope. Thus a higher-resolution camera does not necessarily translate into higher resolution photomicroscopy images, because the microscope itself introduces the resolution-limiting optical elements. This is a proper approach to the task, where the camera should be chosen to capture an image of some specified area, consistent with the resolution limits and field size of the microscope. The advantage of a better camera is chiefly the larger field size it can capture at the resolution limits. To the left is a thumbnail of another Lincoln penny image taken with the higher-resolution camera at something less than the maximum magnification. We can see a field of up to 0.9 inches diameter at this resolution of 2000 pixels/inch, with the whole item imaged at once instead of just the nose. Using combinations of the camera and microscope zoom lenses, the magnification can be increased by another factor of about four to 80X or so, but vignetting will start to reduce the size of the object area. Here are some more digital camera microscope adapters we made for a customer. These slide over a slightly smaller 1.135″ eyepiece on a Bausch and Lomb microscope. The smaller item on the left provides an M41×0.5 thread for an Olympus C-3020 digital camera. The larger item on the right provides an M62×0.75 thread for an Olympus E-10 or E-20 digital camera. We used commercial 6061 aluminum round stock for these. The threads on the left look uneven because of an interference pattern with moire effect on the digital photo. Note the optical illusion which makes the bore look larger on the left adapter compared to the right; they are in fact equal. This adapter we made for a customer with a Nikon Coolpix 5700 digital camera and a Nikon Labophot microscope. That Nikon camera is unusual because although it is a rather advanced model, the zoom depends on the lens turret extending various distances in and out of the camera body, like many snapshot cameras. While the lens hood provides a threaded ring, because of the turret extension, you cannot mount a filter or adapter directly to those threads; instead you must use a Nikon UR-E8 adapter, which is essentially a 34mm long step-down tube from male M53.5-0.75 to female M50×0.7. This tube has an ID=51mm and OD=55.75mm, with a stop ridge of 47mm ID at 5.5mm inside of the female threads. This is the black item in the photos. The aluminum microscope adapter I made mated to the M50×0.75 thread on the UR-E8 adapter and received a 23mm Nikon Labophot microscope eyepiece via a slip fit, overall length of 1 inch. After taking these specimen photos, I enlarged the 23mm bore to 29.2mm to slip over the external diameter of the Labophot eyepiece. Another unusual feature of this adapter is that it can be screwed inside the UR-E8 adapter, or reversibly outside, depending on the camera lens turret extension. This allows the microscope eyepiece a 1.75-inch vertex range relative to the camera, to accomodate various zoom settings while minimizing vignetting. The photos to the left show the reversible mounting. We made a similar large adapter, with nylon thumbscrew, to adapt a Nikon D70 digital camera with a 70-300mm zoom lens and 62mm lens thread or the M62×0.75, to a Celestron 4060 microscope eyepiece with a 1.100 inches outside diameter.

This adapter is different than the others in that instead of an unthreaded sliding fit to a cylindrical microscope eyepiece, the adapter provides a female thread to connect to C-mount threads on the microscope. It is essentially a 1/4″ thick aluminum washer with threads on the inside and outside edges. A similar approach would work for the Canon LA-DC58D conversion lens adapter, which provides a 58mm filter thread for the Canon Powershot G6 camera. Likewise for the LA-DC58 for the Powershot G1 and G2, and the LA-DC58B for the Powershot G3 and G5. This adapter we made for a customer’s Olympus C-4000 camera, which provides a 43mm filter thread mount. The smooth inside bore slips closely over the eyepiece, 1.162 inches outside diameter of a Bausch and Lomb inspection microscope. The height in the photo shows my standard 1-inch overall length for these adapters. We have also begun including a rubber O-ring with each of the slip-type adapters. For example, for this adapter with a 1.162″ inside diameter, a standard inch-series #213 Buna-N O-ring ID=15/16″, OD=1-3/16″, section=1/8″ fits snugly into the inside diameter without distorting. This provides a cushion against which one can rest the front of the lens turret to achieve a near-minimal vertex distance to the eyepiece optics. To increase the vertex distance, one can insert more of the same O-rings in a stack. This adapter also required an additional modification to accommodate the turret lens of the camera projecting 0.050 inches beyond the end of the Olympus CLA-1 41mm-43mm adapter/extension tube for this camera. Since the step ending the 43mm female threads inside the Olympus tube was 0.115 inches deep, a total length of at least 0.165″ had to be relieved inside the threaded end of the adapter, with an inside diamter of 1.575″ or 40mm to allow passage of the 1.45 inches dia extending lens turret. Most camera filter threads have a tiny 0.75mm spacing pitch. Threads cut properly on a lathe wiil have a smooth finish and correct profile. Good-quality threads attach easily to the camera lens, and ensure a secure attachment. We usually design the threaded length to span about ¼ inches, which is about 8 to 10 fully threaded turns, like you see here. Full engagement to the camera lens typically requires only 2 or 3 careful turns. Should the initial threads of an adapter ever be damaged, such as by dropping it or accidentally cross-threading it into the lens, we can repair it on the lathe by simply facing off a bit of the threaded end, exposing new, undamaged threads at the adapter face. This custom adapter connects the 37mm filter thread on the customer’s camera to an American Optical inspection microscope 10X eyepiece having a 1.180 inches outside diameter. This adapter is a bit thin, but still strong enough for the mounting task. In cases where the camera threads happen to be smaller in diameter than the outside of the eyepiece, the adapter uses a shoulder to step up the body diameter and maintain strength. There are also photo shows how the eyepiece joins precisely to the adapter with a slip fit. This provides an accurate axial alignment, which minimizes aberrations and distortions in the photo images. By having the customer send the actual eyepiece, a very close fit is guaranteed on the first try. These slip fits are designed to be close enough for a telescoping fit between the eyepiece and the adapter, allowing an adjustable range of vertex distance. The adapter can be fixed on the eyepiece by assembling with a bit of tissue paper or other thin shim for a tight fit. Or, a bit of white glue or cyanoacrylate glue or super glue into the gap creates a semi-permanent attachment; since CA glue does not bond strongly to the oxidized aluminum surfaces of the adapter and eyepiece, the bond is more of a wedge casting than a true glued bond, and the pieces can be later separated and the glue cleaned off if needed. We can also add an optional ¼ inches-20 threaded hole and nylon thumbscrew to the adapter as a clamp. The custom adapter mounts a Nikon 4500 digital camera with 28mm threads to an Olympus SZ-CTV microscope adapter. The Olympus adapter provides a cylindrical slip fit with a thumbscrew. The custom adapter mounts a Nikon Coolpix 950 digital camera with 28mm threads to a Leica microscope eyepiece with 1.126 inches outside diameter. This is an unusual adapter in that the eyepiece diameter exceeds the camera threads, requiring a stepped shoulder on the adapter. This custom adapter mounts an Olympus C-750 digital camera via the 55mm Olympus CLA-4 adapter tube to a cylindrical microscope eyepiece. These custom adapters are threaded bushings, with C-mount 1 inches-32threads on the outside, and ¼ inches-20 threads on the inside. Lengths are 10mm and 14mm. The cost of a small item like this by weight roughly equates to gold. Precision instrumentation is not cheap. Here the same two adapters are reworked to ½ inches-20, UNF fine inside threads, with a third adapter of 16mm length. This custom adapter mounts a 37mm camera thread or M37×0.75 to a 1.310 inches outside diameter cylindrical Bausch & Lomb inspection microscope eyepiece. Note the use of a fitted O-ring as a cushion for the front of the camera lens, which minimizes the reflex distance and vignetting. We provide the correct O-ring(s) as needed with the adapter. Custom adapter mounts a 30mm camera thread (M30×0.75) to a 1.152″ outside diameter cylindrical Bausch & Lomb inspection microscope eyepiece. This mounts a Sony DCR-TRV11 or DCR-TVR27 video camera to the scope. Custom adapter mounts a 37mm camera thread (M37×0.75) to a 1.221″ (31mm) outside diameter cylindrical Nikon CoolPix MDC lens a relay lens for a Leica MZ16 and other microscopes, also called an MDC-A or MDC-relay, presumably just an acronym for microscope digital camera adapter. The close-fitting smooth inside bore of the adapter provides a telescoping mechanism which with the single nylon clamping screw 1/4″-20 x 1 inch provides an adjustable vertex distance between camera and microscope. Male threads M28×0.75-3mm at the end of the MDC lens are not used; a fixed step-up ring 28mm to 37mm, a standard item from photographic suppliers, is an alternative for a fixed-vertex-distance adaptation.

Custom adapter is a threaded-flanged bushing which adapts the 28mm (M28×0.75) female thread of the Nikon UR-E6 adapter to a female C-mount thread (1″-32) for attachment to a microscope lens. The flange allows one or two O-rings to be inserted to adjust the vertex distance. This bushing weighed only 3.6 grams, and the inside and outside threads cleared each other by a thickness of less than 1mm. The finished item was priced at about 3 times the cost of gold by weight. Custom adapter mounts a Canon EOS Digital Rebel 300D digital SLR with 18-55 EFS lens of 58mm camera thread, M58×0.75 to a 1.154″ or 29.3mm outside diameter microscope eyepiece, namely a Leica Mark X Gemolite Stereo Zoom with 15X W.F. eyepieces. The three nylon screws 1/4″-20 x 1-inch allow for vertex distance adjustment. Custom adapter retrofits a Canon EOS 20D digital camera to the camera port of an ophthalmological instrument, a Topcon slit lamp Topcon SL-5D slit lamp and Topcon SL-6E slit lamp. The camera port in the original design accepted an obsolete Topcon 35mm film camera back. The first photo shows the original bayonet ring mount for the film camera. The second photo shows two components used in the new adaptation, the custom adapter on the left providing T-mount threads, and an off-the-shelf T-mount-to-EOS mounting ring on the right. These two combine and mount to the camera port in place of the original bayonet ring. The custom adapter provides a male T-mount thread M42×0.75, on which a commerical adapter T-mount to EOS is then attached for the camera. The third photo shows the final assembly of the camera port, ready for a Canon EOS camera. Adapting in two pieces via an intermediate T-mount thread has several benefits: it avoids having to machine the more difficult EOS bayonet lens fitting, it allows rotation of the camera on the instrument, it provides an adjustable vertex distance; and it is compatible with many other T-mount items. The T-mount-to-EOS ring can be purchased inexpensively off-the-shelf, as well as for a wide variety of other camera lens standards. The T-mount intermediate also supports Nikon digital SLR cameras. There are available adapter kit converts a Topcon TRC-50VT retinal camera also known as a fundus camera from the original film camera back to use a Canon EOS digital SLR camera. The kit consists of: • A mechanical adapter to mount the Canon digital camera on the Topcon instrument in a precisely parfocal, axially centered position. • A modified breech ring that replaces the original Topcon ring, which avoids the mechanical interference of the flash “nose” of certain Canon SLR models with the instrument. • An neutral-density filter for the Topcon instrument, which reduces the instrument’s flash intensity to compensate for the Canon digital SLR’s improved light sensitivity. • A flash synchronization adapter cable, which triggers the Topcon instrument flash in synchronization with the Canon digital camera shutter. This cable adapts the Canon digital camera flash trigger signal to the DB-15 connector provided on the Topcon TRC-50VT, which was originally intended for a Polaroid camera. Modified versions of this kit also adapt the Topcon TRC-50X and TRC-50EX retinal cameras to use Canon digital SLR cameras. This viewfinder magnifier for Canon digital SLR cameras is a custom telescopic component we made, which provides a 2X magnified and inverted enlargement of the standard viewfinder. This is designed to compensate for the inverted view resulting from adaptation of certain instruments like the Topcon retinal cameras described above. Custom adapter retrofits a Canon EOS 20D digital camera to the camera port of a Topcon fundus camera, another ophthalmological instrument also known as a Topcon retinal camera. The approach differs from the slit lamp adaptation. First, I disassembled the bayonet mount from the old film camera, and made a T-mount adapter to fit its bolt circle screw pattern. Onto this I added an off-the-shelf T-mount-to-EOS mounting ring. These three parts combine to connect the fundus camera optics to the EOS 20D digital camera. The thin threaded bushing adapts a 2″-40 threaded instrument to a M58×0.75 lens thread. Note the split ring design which prevents seizing of the small pitch inside threads on the large outside diameter instrument. Note also the small dimples 1/16″ diameter x 1/16″ deep for a spanner wrench tool to insert and remove the adapter. A custom adapter for a 1.25″ outside diameter telescope eyepiece to an M50×0.75 lens thread. Opposing nylon thumbscrews lock the eyepiece in position, while allowing vertex distance adjustment.