Foraminifera sample from Timor (historic material in collections, from an expedition in the 1960s or 1970s), mostly planktonic but some benthic forams in the mix. Sony Aplha R II, Laowa 25 mm at 5x f/4, shot with MJKZZ Ultra Rail Mini, stacked with Zerene Stacker (DMap), background removed in Photoshop (mostly Magnetic Lasso tool). The background was a standard black plastic micropal well-slide, which as usual was full of very fine crystalline dust, and required complete masking away. The subject is shiny and mostly translucent white, with very low contrast. The 1:1 pixel crop shows some fine detail, in spite of not shooting at f/2.8 (which would display a little more detail). One pixel corresponds to 0.9 μm on the subject.
PS - The 1:1 crop shows internal canals in the test* wall, visible through the translucent structure of the test wall. Most of the time, modern scientific publications on forams are illustrated with SEM images, which display surface detail with a resolution and DoF unattainable with optical imaging. However, SEM images do not show the internal test structure, which requires additional images of sectioned or broken tests, or time-consuming techniques like filling the test pores and canals with a resin and etching away the calcareous test material with an acid. Therefore, there is potentially a use for focus stacking in foram research, so far not so common in the modern literature because virtually all well-equipped research labs have an SEM. Traditional "single-shot" optical imaging is generally not used because the limited DoF makes the images unsuitable for illustration. Historic foram research solved this problem with hand-crafted illustrations, these days rarely used (except for simple, non-shaded line drawings) because of their high cost and potential for subjective "interpretation" of what the observer saw.
A few foram studies are illustrated with images from an optical scanning microscope (which could be regarded as a precursor of focus stacking), for example https://palaeo-electronica.org/2003_1/b ... enthic.pdf
* test is what the "shell" of forams is called. CF. the ancient "Testacea" term used for forams, and by extension even for mollusc shells in 19th century and earlier literature.
Foraminifera from Timor
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