While a lot of information regarding to the finite Olympus BH and CH systems exist, information on Olympus’ modern universal infinity system is scarce. Adaption methods can be ascertained from various microscopy websites and digging through manuals. I had to build my setup this way, and the process to acquire accurate information was simply painful. Through trial and error, I built a system that satisfies my needs for photomicrography, with image quality and the artistic aspect taking priority over convenience and mass production.
There exist several methods to take photos with a microscope. The author (I) is familiar with three of them. These three methods are projection with a photo eyepiece, direct projection, and imaging through the eyepiece. I prefer direct projection to my full-frame Nikon camera. Smartphones are also a good tool to share quick and simple images straight to a friend, a client, or colleague.
Direct projection is the act of mounting a camera to a microscope without the aid of a ‘photo eyepiece (PE)’. Olympus offers a total of five photo eyepieces with magnifying powers of 2x, 2.5x, 3.3x, 4x ,and 5x for their BX universal infinity system.
The eyepiece is typically a thin tube housing optics and sits in a larger tube. For Olympus, a U-SPT or IX-SPT is required to house photo eyepieces. They are designed to provide a rectangular image projected onto the camera’s sensor, which effectively crops the circular image produced by the objective lens. A PE2.5x is required for full-frame cameras, the rare PE2x is suitable for crop (APS-C) sensors. If more magnification is needed, one can go up to 3.3x, 4x, and 5x.
The most intuitive method to acquire high-quality images with a consumer camera is utilising photo eyepieces. I will discuss all three methods I am familiar with and explain why I prefer direct projection.
Photo eyepiece setup
Several components are needed if one desires to utilise photo eyepieces. This is the most expensive method that can get reach serious heights if components are lacking. The pre-requisite to using photo eyepieces is access to a trinocular head or a dedicated tube lens (U-TLU or U-SWTLU-C). With only a binocular head, the U-DPT beamsplitter dual-port adaptor (and similar models) is needed, this is a part that costs more than $400. When a dedicated tube lens is used, binocular viewing is completely gone.
While it is possible to use photo eyepieces with a custom tubing setup, I decided to stick to original Olympus parts. A Thorlabs’ system was built previously but it was too much hassle and I needed the tubes.
Illustrated above are a set of photo eyepieces, the U-SPT tube which houses one of the photo eyepieces, and a modified Olympus Photomicro Adapter L.
The modification is simple, I purchased an OM to Nikon F flange adaptor. The included screws were too long and Olympus’ original screws had a cap too large, so I simply sawed the included screws down to the correct length. The replacement of this mount is incredibly simple. If I recall correctly, the F-mount flange distance is 46.5mm whereas the OM-mount flange distance is 46mm, the mere difference of 0.5mm makes a mechanical adaptor infeasible to construct. I use the Nikon Z mirrorless system, it is possible to directly adapt the OM-mount, however, my adaptor was a piece of junk. Buying Laina branded adaptors is like a lottery.
Unless an OM-mount (film) camera is used, an adaptor is always needed in this situation.
The photo eyepiece sits snuggly inside the U-SPT. This setup costs $250-$300 for parts alone. The Photomicro Adapter L is expensive, they commonly sell for $200-$300. The U-SPT is around $20-$50, and the photo eyepieces are either very cheap or near impossible to find depending on which one is desired. The PE2x for APS-C sensors and PE5x are very hard to come by and not exactly cheap.
Diagnostic Instruments offer a Photomicro Adapter L equivalent which is well made and also expensive. The PM-D35-S for OM-mount film cameras can also be used, please make sure the Photomicro Adapter H (the physical OM-mount) is present, it is nearly impossible to find as an alone unit. Check the references for a link to Alan Wood’s excellent resource for more information.
Sometimes modified Photomicro Adapter L tubes show up online, they are said to be 10mm taller than usual which could complicate adapting.
Direct projection is my preferred method. The method in the previous section makes the system very tall, making it hard to see the camera’s live view monitor. Moreover, it is just ugly. The colour of the Photomicro Adapter L does not match the BX microscope, and the U-SPT is matte black.
Setting up direct projection is quite trivial, however, original Olympus parts can be hard to find.
I have been using a Thorlabs based setup with a custom adaptor for some time. The total cost of this custom build illustrated on the rightmost is around $150, way too expensive. I sourced both original Olympus parts, the U-TV1x-2 and U-TMAD for $91 from a good mate, showcased in the middle. A cheap junky T2 (M42x0.75) adaptor is displayed here as well before a better one comes in.
The heavy-looking tube on the leftmost is a direct projection adaptor made by Diagnostic Instruments, rebranded as Optem. This part is around $100, way too heavy, but solid. Olympus’ equivalent would be the U-TV1x-2 and U-CMAD.
If a scientific camera with a C-mount is used, the setup is very simple.
The poorly designed U-TV1x-2 and U-TMAD will not work on a full-frame camera (35mm) without modification. Heavy vignetting is induced. Inside the U-TMAD, a piece of black light-blocking plastic can be seen, it must be removed if a full-frame camera is used. A crop sensor camera should work without any modifying.
I attempted to modify mine, now it is destroyed. Hurrray…
With the concentric circle removed, we run into another glaring issue, pun very much intended. While the corners no longer suffer from mechanical vignetting, a circular halo has ascended. The central portion is unusable as well, a prismatic hue is present. This is caused by the shiny internals, projecting stray light back onto the sensor. I tried to alleviate this issue by modifying the light blocker, it did not do much.
Instead of flocking or expensive light-absorbing paint such as Teflon coatings, Olympus just added two shrouds and called it a day.
To eliminate stray light issues, both tubes must be fully flocked. This includes the shiny internal rim of the U-TMAD. With the light blocker in place, the halo is simply culled. Notice how the rim faces away from the sensor? It bounces back into the sensor via another shiny surface of the U-TV1x-2, which I have flocked as well. Congratulations, the cost-effective solution… backfired. I went ahead and flocked every visible shim while leaving enough clearance in the U-TMAD to mate the U-TV1x-2 with. The halo and other odd glare hotspots are completely gone.
Once again, various other options are offered as well. Diagnostic Instruments offers a “D10 BXF” adaptor which allows focus adjustments, presumably to pinpoint infinity focus.
Smartphone photo capture through the eyepiece
There are many brackets on the market of various quality offered to make this task easier. I believe it achieves the opposite since the bracket must be removed if I want to use my trinocular head for viewing again, which is always.
To take smartphone photos, I simply go into my camera app’s full manual mode, dial focus to infinity and back a little, then hold the phone above the eyepiece. I use my fingers to support this action, decreasing hand wobble. The results are usually more than adequate. Modern smartphones offer telephoto and wide-angle options. With the telephoto option, it is possible to eliminate the heavy mechanical vignetting.
The darkfield photo above on the left and two photos using the differential interference contrast technique were captured with an old OnePlus 5. This is a Chinese Android phone known for being good for the wallet and mediocre image quality.
Aside from the three methods above, some projection methods involve specialised adaptors with optics built-in. These adaptors extend the field of view by shrinking the magnification, which is paramount to small sensor cameras. I have no experience with those.
I stick to direct projection with the aid of a magnification changer to extract the most resolution possible out of my objectives. This is a matter of preference, some of us are in this field for work and research, where other methods are preferable. It is also important to make sure that the eyepieces are parfocal to the detector, which is a camera in the context of this article.
Information on photo eyepieces: http://www.alanwood.net/olympus/photo-eyepieces.html
Information on Olympus Photomicro Adapter L: http://www.alanwood.net/olympus/digital-slr-bh2-microscope.html
Olympus Photomicro Adapter L specifications: http://www.alanwood.net/olympus/photomicro-adapter-l.html