Material on the lens especially for Radozhiva prepared Rodion Eshmakov.
Semiplan 3.2×0.1 in the revolver of the M10 microscope.
Semiplan 3,2/0.10 160/- (hereinafter referred to as Semiplan 3.2×0.1) is a simple old DIN standard review objective for microscopes with a finite tube distance such as Carl Zeiss Jena Amplival, Laboval. In terms of parameters and image quality, the objective is very similar to cheap modern Chinese achromats type 4x0.1, which are included in the standard kit of many biological microscopes.
Technical specifications
Optical design – 2 lenses in 1 bond, achromatic doublet;
Type of correction – achromat;
Tube distance – 160 mm;
Magnification factor – 3.2x;
Numerical aperture – 0.1;
Working distance – 19.6 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
The design of the objective is extremely minimalistic, if not primitive. The objective consists of two parts - 1) a brass black frame with a rolled lens joint and a thread for attaching to the microscope and 2) a tube made of nickel-plated brass with a hole - a field diaphragm. The achromatic doublet cannot be removed from the frame.
The inside of the tube and the lens space have a high-quality matte blackening, but there is no enlightenment on the surfaces of the achromat. However, this is much better than in Chinese lenses, where there is enlightenment, but there is no sense in it, because in the absence of normal blackening, the contrast is still bad. Since the lens has only two glass-air interfaces, its light transmission remains high in the wavelength range from 400 to 1100 nm with a short-wave transmission limit of about 320 nm.
Light transmission spectrum of Semiplan 3.2×0.1.
According to X-ray fluorescence analysis, the objective lens facing the object is made of heavy crown glass, and the rear lens is made of heavy flint glass.
XRF spectrum of the front lens element.
XRF spectrum of the rear lens element.
Structurally, the Semiplan 3.2×0.1 is nothing more than a well-made, but very simple lens without any features that could distinguish it from modern or not so modern analogues.
Optical properties. Comparison with USSR analogues
The lens has good sharpness in the central area of the frame, but beyond the field of ~20 mm the image quality drops significantly due to the influence of astigmatism. It is impossible to achieve a sharp image at the edge of the field by refocusing. So the Germans clearly gave the name "Semiplan" (i.e. "half-plan", i.e. "a lens with partially corrected field curvature") with an unreasonably optimistic view of reality.
The image contrast level is quite good thanks to the simple optical design and well-designed lens protection.
Comparison with Progress OM-3 Plan 3.5×0.1 and Progress OM-12 3.7×0.11 (with enlightenment) showed that in the central area the Semiplan is not much behind the 3.7×0.11, but in the field it is much worse than both Soviet lenses. The photos were taken on a Sony NEX-6 in prime focus.
Taking into account the good correction within the field of ~20 mm, the Semiplan 3.2×0.1 is quite suitable as a survey lens for visual observations or for photography with low-resolution 1” matrices.
Below are some examples of photos taken with a Sony NEX-6 and a modified NPZ M10 microscope.
Objects in the photo: 1 – nickel-ammonium schenite, 2 – chromium(III) acetylacetonate, 3 – ceramic substrate with a microheater and a layer of semiconductor oxide on a gas sensor chip, 4-5 – iron(III) acetylacetonate, 6 – copper-ammonium schenite.
Below are some images taken using the same equipment but stacking.
Objects in the photo: 1 – chromium(III) acetylacetonate, 2 – ceramic substrate with a microheater and a layer of semiconductor oxide on a gas sensor chip, 3 – a fragment of a hard disk board, 4 – a membrane MEMS chip of a gas sensor, 5-6 – iron(III) acetylacetonate, 7 – copper-ammonium schenite, 8 – nickel-ammonium schenite.
Conclusions
Carl Zeiss Jena Semiplan 3.2/0.10 – too simple to be really good. The lens is of real value only as part of an authentic optics kit for an old Zeiss microscope, although it is also quite suitable as a survey lens for visual observations. But there is no point in using it for photography in prime focus – for this purpose, a very cheap and widely available Chinese lens is much more suitable. 4×0.1 Plan.
