I've been trying to build a decent quality DSLR setup for my trinocular Reichert Microstar IV, and I could use some advice from the resident microscope experts on how to fix the problems I'm seeing (or - maybe these issues are expected with this microscope). I'm at a point now where I can capture images, but I'm disappointed with the quality I am getting: No matter what I do, the images seem blurry and contain chromatic aberrations.
I have a Reichert #1943 trinocular head, but I haven't been able to find much information about the intended camera adapter that fits onto the trinocular port (it is a 40mm male dovetail) and whether it contained any optics, so I am mostly guessing here. The head itself has a slider for a 100/0 split, where the slider moves a prism out of the way so that there are no optics between the trinocular port and the tube lens (other than a mysterious glass cylinder). The port itself is shaped like this:
![Image](https://benedikt-bitterli.me/micro/trinoc/trinoc-port.jpg)
I am using a Canon EOS 7D, and I've been experimenting with two different setups for image capture: A direct projection setup, with the bare camera sensor located at the intermediate image plane and no optics between camera and tube lens; and an afocal setup, with a third eyepiece mounted in focus atop the trinocular port and the camera looking through the eyepiece (with a Canon 50mm f/1.8 lens) focused at infinity.
Pictures of the two setups are below: Direct projection (left), Afocal (right)
![Image](https://benedikt-bitterli.me/micro/trinoc/direct.jpg)
![Image](https://benedikt-bitterli.me/micro/trinoc/afocal.jpg)
To mount the camera I'm using a DYI adapter tube, fixed to the microscope using a 3D printed adapter that replaces the original port:
![Image](https://benedikt-bitterli.me/micro/trinoc/3d-adapter.png)
The adapter holds an M42 ring that leads into M42 macro extenders and a helicoid to fine-adjust the focus. For the afocal setup, I am mounting an eyepiece inside the macro extender tube closely in front of the camera lens. I designed a 3D printed eyepiece holder, but it was destroyed in the mail, and so for now I am testing using a makeshift wedge made out of cardstock that holds the eyepiece in the tube:
![Image](https://benedikt-bitterli.me/micro/trinoc/eyepiece.jpg)
In the end, the mechanical setup goes something like:
3D printed adapter -> M42 thread -> macro extension tubes -> helicoid -> M42-to-EF adapter -> camera (for direct projection)
3D printed adapter -> M42 thread -> extension tubes -> helicoid -> extension tubes -> eyepiece -> step-up ring -> Canon 50mm f/1.8 lens -> camera (for afocal)
I've been doing some comparisons to see whether either setup gives me satisfactory results, and I have been testing using a reticule from an eyepiece that I was able to remove.
Below I'm showing results from both direct projection and the afocal setup, at 40x/100x/400x magnification both at horizontal and vertical orientation of the reticule. There is no cover glass, just the glass reticule sitting on top of a microscope slide (so not optimal). Images were shot by focusing through the eyepieces, then adjusting the helicoid until the camera was parfocal with the eyepieces. For the afocal setup, I adjusted the helicoid without the camera attached until the image looked sharp through the eyepiece in the adapter tube. I then attached the camera, focused at infinity.
Results below:
Direct projection: 40x, 100x, 400x (click images for full-res)
Afocal: 40x, 100x, 400x (click images for full-res)
While I don't know what the quality ceiling is for this scope/camera combination, I can't say I'm fully satisfied with either of these. The direct projection setup is acceptable, but especially at lower magnification, the image looks a bit hazy. There is also a lot of chromatic aberration towards the edges, which is not great. These aberrations are not present when looking through the eyepieces, as far as I can tell.
The afocal setup is really not very good. The images are hazy and the chromatic aberrations are extreme. Aberrations are not symmetrical which is mysterious.
For now it seems the direct projection setup is just barely usable. Images shot under more realistic conditions look something like this (click for full res):
![Image](https://benedikt-bitterli.me/micro/trinoc/thumbs/fungus.jpg)
The quality is disappointing however - even though the image looks very sharp in the eyepieces, the image from the camera just feels blurry even when shooting at the shortest exposure time. The 7D that I'm using has a low-pass filter which may be contributing, but overall it feels like the quality I'm getting out is less than it could be. For reference, here is an image of diatoms that I shot with a hand-held cell phone through the eyepieces (click for full-res):
![Image](https://benedikt-bitterli.me/micro/trinoc/thumbs/cell-capture.jpg)
Even with a much cheaper phone camera held much less robustly (compared to the DSLR setup), the image is sharp and free of aberrations as I would expect.
I'm curious if anyone has any ideas on where these issues stem from and how I could possibly fix them. Maybe there's a glaring mistake I'm making?