Material on the lens especially for Radozhiva prepared Rodion Eshmakov.
Semiplan 6.3/0.16 in the revolver of the M10 microscope.
The Carl Zeiss Jena Semiplan 6,3/0,16 objective (hereinafter referred to as Semiplan 6.3×0.16) is an old low-magnification objective for microscopes with a finite tube distance such as the Carl Zeiss Jena Eduval, Laboval. In terms of magnification, the objective occupies an intermediate position between typical values of 4× and 10×, so it can be used to replace both of them. The numerical aperture value of 0.16 is quite standard and expected; from the standpoint of diffraction-limited resolution in image space, this is equivalent to 0.1 for a 4× objective and 0.25 for a 10× objective.
Technical specifications
Optical design - 4 lenses in 1 groups, aplanat;
Drawing of the optical scheme of the lens.
Correction type – achromat with improved field curvature correction (semi-plan);
Tube distance – 160 mm;
Magnification: 6.3×;
Numerical aperture – 0.16;
Working distance – 8.5 mm;
Parfocal distance – 45 mm (DIN standard);
Cover glass thickness: 0-~2 mm;
Immersion required - no;
Mounting type – RMS standard (4/5” x 1/36” thread);
Features - microscopic lens, does not have an iris diaphragm and a focusing mechanism.
Lens design
Semiplan 6.3×0.16 is made in a completely metal case. The design is very simple: two metal frames with glues and an interlens insert are placed in a tubular case and fixed with a slotted nut. The lens does not require additional centering of the elements after disassembly, so it is quite easy to maintain.
The inner surfaces of the lens have a matte blackening and ribbing, which is extremely important for achieving an acceptable level of image contrast. Although, of course, the coating cannot be called ideally black. The lenses of the lens do not have an anti-reflective coating, unlike, for example, the lens Carl Zeiss Jena 40x0.65 DIN. Alas, it was not only the USSR that saved on coating. The light transmission spectrum of the lens looks even in the range of 400 – 1100 nm, which covers the visible region with a reserve. The lens has good transmission in the UV range: the short-wave limit corresponds to ~320 nm.
Light transmission spectrum of Semiplan 6.3×0.16.
The optical design of the lens does not use special grades of glass. According to X-ray fluorescence analysis, the front lens of the lens is made of flint or heavy flint (completely analogous to the glass of the front lens of the Soviet lens OM-13P 9×0.2), and the rear one is made of barium or heavy crown (probably of the type LZOS BK8 547.628, TK12 569.629), similar to the material of the front lens of the objective CZJ 10×0.3In this respect, the German lens differs from
Soviet 8×0.2 M-42 or 9×0.2 OM-13P, the positive lenses of which are made from ordinary crowns.
XRF spectrum of the front lens of the Semiplan 6.3×0.16 objective.
XRF spectrum of the rear lens of the Semiplan 6.3×0.16 objective.
It can be concluded that the Semiplan 6.3×0.16 is a development of the idea of a universal low-power objective lens like the old 8×0.2, where the parfocal distance is increased from 33 to 45 mm to improve the characteristics, which has a positive effect on the quality factor of the system, and instead of the usual crowns like K14 515.606 (Schott K7), newer glasses with a higher refractive index are used.
Optical properties
The Semiplan 6.3×0.16, surprisingly, turned out to be a rather pleasant and high-quality lens, which cannot be said about the overview lens. Semiplan 3.2×0.1 from the same line of optics. The lens has a good degree of correction of spherochromatic aberrations and, most importantly, astigmatism for such a simple optical scheme: even despite the presence of significant field curvature, it is possible to achieve a sharp image at the edges of the APS-C frame field by refocusing or stacking.
Even despite the smaller magnification and aperture, the lens is only slightly inferior to the Soviet one in terms of detail in the center of the frame. Plan 9×0.2 OM-2, and in terms of image quality across the field it is ahead of the rather successful Soviet one Epi 9×0.2 OE-9, and modern Chinese Achromat 10×0.25, and already mentioned Plan 9×0.2 OM-2.
Of course, the lens cannot be called ideal: in many situations it chromatic aberration in the form of purple halos on contrasting borders are quite noticeable, and the image contrast could have been better if Eastern Zeiss had not been stingy with coating. Nevertheless, the Semiplan 6.3×0.16 is better than many other similar lenses.
Below are shots taken with Semiplan 6.3×0.16 and Sony NEX-6 camera in prime focus.
Objects in the photo: 1) Benzoic acid (dark field, KF-1 condenser); 2) Calcium benzoate (dark field, KF-1 condenser); 3) Calcium benzoate (light field, crossed polarizers), 4) Benzoic acid (light field, crossed polarizers); 5) Potassium oxalatocuprate hydrate; 6) Potassium oxalatocuprate hydrate (dark field, condenser OI-10); 7) Cobalt(II) sulfate hydrate with an admixture of basic salt (dark field, condenser OI-10); 8) Cobalt(II) sulfate hydrate with an admixture of basic salt; 9) Potassium thiocyanatocobaltate hydrate, 10) Stained section of spinal cord; 11) Ammonium persulfate; 12) Ammonium persulfate (dark field, condenser OI-10); 13) Sulfur crystals; 14-15) Sulfur crystals (dark field, condenser OI-10); 16) Porous nanocrystalline tin dioxide (dark field, condenser OI-10); 17) Porous nanocrystalline tin dioxide (reflected light); 18) Sample of tin dioxide - manganese oxide (dark field, condenser OI-10); 19-20) IPS smartphone display.
Then – photographs taken using stacking.
Objects in the photo: 1) Benzoic acid (dark field, KF-1 condenser); 2) Calcium benzoate (dark field, KF-1 condenser); 3) Calcium benzoate (light field, crossed polarizers), 4) Benzoic acid (light field, crossed polarizers); 5) Gas sensor membrane chip; 6) Potassium oxalate cuprate hydrate; 7-9) Molybdenum disulfide; 10) Potassium oxalate cuprate hydrate (dark field, condenser OI-10); 11) Cobalt(II) sulfate hydrate with an admixture of basic salt (dark field, condenser OI-10); 12) Cobalt(II) sulfate hydrate with an admixture of basic salt; 13) Potassium thiocyanatocobaltate hydrate, 14) Stained section of spinal cord; 15) Ammonium persulfate; 16) Ammonium persulfate (dark field, condenser OI-10); 17) Sulfur crystals; 18-19) Sulfur crystals (dark field, condenser OI-10); 20) Porous nanocrystalline tin dioxide (dark field, condenser OI-10); 21) Porous nanocrystalline tin dioxide (reflected light); 22) Sample of tin dioxide - manganese oxide (dark field, condenser OI-10).
Conclusions
Semiplan 6.3/0.16 can be called a quite successful microscope lens, well suited for photography, like the famous Soviet lens OM-12 3.7×0.11. A simple optical scheme provides an acceptable level of image quality both in the center of the frame and across the field. The disadvantages include the lack of coating and low availability on the secondary market.
