The description says that it is plan corrected. The lens marking and description give the 160mm tube length, which also means that it is finite conjugate.
It does not give the parfocal distance, which unfortunately is common. However 45mm is by far the most common standard, and lenses with 35mm par-focal distance do usually have something tell-tale in the description (often they say â185â somewhere), and would look shorter.
You can certainly use the AmScope PA40X-V300 objective with the OpenFlexure Microscope. However, please note that its working distance is only 0.63 mm. In practice, this means that when examining specimens on a standard microscope slide, you may need to image through the coverslip side or even invert the slide to achieve proper focus and avoid contact between the objective and the specimen.
For greater flexibility and ease of use, I would recommend considering an objective with a longer working distance. Although they are typically more expensive, objectives designed for inverted microscopes often provide substantially higher working distances and are much better suited for thicker samples or applications where additional clearance is required.
Thanks @Ertan - itâs worth noting that a 40x objective is usually âcoverslip correctedâ for a specific thickness of glass, and this does matter: imaging a sample directly gives a lower quality image than imaging through the correct coverslip, using the objectives we typically buy (which are more or less the same spec as the AmScope one).
The link is to an objective specced for a standard 0.17mm coverglass, so thatâs what you should image through. If you get a longer working distance one, itâs worth checking whether itâs designed to image through 1.5mm of glass, because if itâs intended to image only through air, your resolution will be significantly worse if you then image through a slide.
This matters more as you go to high NA (usually meaning 40x and above). Lower magnification objectives suffer less from spherical aberration.