This is description of this part:
A female dovetail mount with a 42 mm internal diameter, for fitting the photo tube into the trinocular heads of Olympus microscopes.
This particular mount was removed from an Olympus U-TR30 trinocular head.
The Olympus U-TR30 / U-TR30-2 photo-trinocular heads are most often used in the following microscopes:
- Olympus CX30 / CX31
- Olympus CX40 / CX41 / CX43
- Olympus BX40 / BX41 / BX43
- Olympus BX50 / BX51 / BX53
- Olympus BX60 / BX61
- Olympus MX40 / MX50
- and probably others
Olympus offers a whole range of tubes with a 42.1 mm mounting diameter, so such mounts are fitted not only to the U-TR30 head.
The female mount for adapters with a 42 mm dovetail (more precisely, according to the manufacturer specification: 42.1 mm) is found, among others, on the following microscope heads and tubes:
- Olympus U-TR30
- Olympus U-TR30-2
- Olympus U-TR30H
- Olympus U-TR30IR
- Olympus U-TR30NIR
- Olympus U-TTR-2
- Olympus U-ETR3
- Olympus U-ETR30
- Olympus U-ETR-4
- Olympus U-SWTR
- Olympus U-SWTR-2
- Olympus U-SWTR-3
- Olympus U-SWETR
- Olympus U-SWETTR-2
- Olympus U-SWETTR-5
- Olympus MX-SWETTR
- Olympus U-CTR30-2
- Olympus U-TRU
- Olympus U-TRUS
- Olympus U-MPH
- Olympus U-TLU
- Olympus SZX-TR30
- Olympus SZX2-TTR
- Olympus SZX2-TTRPT
- and probably others
Important: as of now (2026) the microscope brand "Olympus" has been replaced by "Evident". Evident microscopes (e.g. Evident BX53) still keep the previous standard, so the 42mm mount is also found in products carrying that brand.
Because this is a brittle casting, the mount can crumble, crack or break. The remedy is then to replace the complete head or just this part - fortunately this mount is a separate component, fixed to the head with three screws.
And this implies another important matter: the diameter of the mount is standard, but I cannot guarantee that a mount fixed with exactly three screws fits every one of those heads and tubes, and even if it does - whether their hole spacing is the same in each of those models. The user should check that for himself based on the photos in the gallery.
Where the descriptions quoting a 51 mm diameter come from?
On the website of "Martin Microscope" and in many other descriptions available online, exactly the same (sic!) mount is described as having a diameter of 51 mm. That is the internal diameter of the ring, measured without the seat of the dovetail taper. So the 51 mm at "Martin Microscope" refers to the same mount into which a 42 mm dovetail is inserted.
This is not a part for one specific microscope model. As listed above - such a mount can be found in many heads and tubes, and these in turn in any microscope the user fits them into.
In the "compatibility" section there is an example list of microscopes the U-TR30 head fits, although it is not a complete list.
What is this part needed for?
- as a service part, in the form of replacing the whole component, when the mount in your head is in very poor condition or has, for example, cracked
- when you need a mount for fitting 42 mm Olympus tubes in order to use them in your own DIY project
