The Bresser Infinity microscope is pretty good but like all microscopes it has its limitations. I am a passionate macro-photographer and thus a camera port on a microscope was a ‘must’ for me. A few minutes reading on the microscope forums provides some information on how to best utilize the port but also flaged up the frustrations involved in trying to attach anything other than c-mount cameras. My first idea was to use an afocal setup i.e. one in which a camera with its lens attached is used to capture an image projected from an eyepiece in the camera port. I am lucky to have an excellent ‘second’ camera – an Olympus EM1 Mk2, This is a micro 4/3rds camera with a sensor significantly larger than in C mount cameras but smaller than those in a full-frame one. I tried a variety of eyepieces and camera lenses, they all worked, but the setups were clumsy and provided images that were not sharp enough for my liking. Also, getting things par-focal with the eyepieces was a bit of a nightmare. Next, I bought and tried fitting my camera to the 2X Bresser camera adapter (see figure below) but it too provided images that were not as sharp as I would like – that was a bit of a blow because the adapter was quite expensive! So, I turned to what might be described as ‘direct projection’. I am unsure of the terminology here as applied to infinity objectives. Albeit that there may be some problems with the absence of corrections left to the eyepieces, tube-length objectives (typically 160mm) can be used to project an image directly onto the camera sensor. However, with infinity objectives there is of necessity an intervening ‘tube lens’ built into the body of the microscope. Thus, while there is no special projection eyepiece, the tube lens does in a sense act as one. I had a few misgivings about focusing the tube lens output directly on a m4/3rds sensor since the image circle it forms is designed only to fill smaller c-mount camera sensors. However, the ability of my camera to use an electronic shutter something that does away with camera shake, its 20 megapixel sensor, and other of its advanced features were far too great a temptation to resist. I had to give it a go.
The Bresser 2X adapter – nicely made but inevitably softens the image.
The trinocular port on the Bresser Infinity microscope with the eyepiece holder removed revealing the threads on the tube lens holder. Note the minor damage done by steel bolts – hence the use of nylon ones! Also note the shim to bring the camera to par-focality.
I started by projecting the image from the tube lens onto some tracing paper to estimate the required distance to the sensor. I probably could have found some data to provide that distance but hey-ho that is what I did. I could see that to make it possible to mount the camera I would have to do away with the eyepiece holder on the camera port (see figure). I then 3d-printed a tube with a flange on the top to which I could screw a metal m4/3rds mount taken from one of a cheap set of extension tubes that I no longer use. The bottom of the tube has 4 brass heat-melt inserts for 3mm screws. 4 nylon bolts screwed into these inserts allows the tube to fixed to the top of the threaded tube lens carrier. When I mounted the camera, I found the tube needed to be a fraction longer and rather than print another one, I just printed a shim about 3.5mm thick to sit beneath the tube. With that done, the camera and the eyepieces were par-focal with one another – or at least very nearly so. I have now designed a tube that is the correct length and places the nylon bolts a little further down on the tube lens holder. The image circle was indeed slightly smaller than the sensor but minimally so and the minor vignetting could easily be fixed using a function for this included in my photo-processing software – Affinity 2.0. The images from direct projection were sharper than I could obtain by any other method. Controlling the camera with Olympus Capture software on my laptop provided me with access to complete control over the camera’s settings and access to functions like High-Res mode that can provide up to 80 megapixel images (serious overkill!!). Though the image on the camera sensor covers a larger area and is concomitantly of a lower magnification, I have not found this to be a problem. Since, the camera sensor has more than enough pixels to stretch the resolution of the microscope to the limit, one could always employ the camera’s digital telephoto facility to double the magnification. However, I haven’t found that necessary.
Top – the camera adapter with the chrome bayonet borrowed from an extension tube that I no longer required.
Lower – the camera in place on the microscope. The lead nearest to the camera is used to control the camera from the Olympus Capture software. The battery compartment is open to allow a dummy battery to keep the camera powered all-day if required.
I hope the above provides a route via which other owners of similar microscopes can attach cameras to their instruments. I will make the 3d print files accessible to others (parfocal version that doesn’t require a spacer now available at https://www.tinkercad.com/things/aq6umhUm8JK-modifiedolympusbressermount?sharecode=ICFcOBZJ3Z_dGYlGKYh5isvDklYA5mpL5KCGE0lj72s) .
Here are some images from my system:
Of course, I went on modifying the microscope and I will post details of adding flash, epi-illumination, z-stacking and remote control functions to it in later posts. These modifications can with a little effort by applied to any microscope.
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