OKS is a family of Soviet cinema lenses manufactured by LOMO. They were used in professional cinema equipment, but often you can find their technical versions. Lenses are marked with three numbers: the first is usually associated with the used optical scheme (they differ from each other in OKS1-75-1, OKS4-75-1, OKS6-75-1, OKS2-75-1), the second corresponds to the focal length, and the third, apparently indicates less significant differences in the optical scheme (OKS1-50-1, OKS1-50-4, OKS1-50-6 - all are six-lens 50/2 planars). OKS lenses are valued in the secondary market for their quality and "convenient" parameters, some of them used the most advanced Soviet designs that were not reflected in mass consumer photographic optics.
The review presents a wide-angle film shooting lens OKS1-22-1 22 / 2.8, designed for cameras with 35 mm film (Konvas-avtomat, Era, Sputnik), adapted for use with modern mirrorless cameras.
TECH SPECS [source: Yakovlev's handbook, vol. 1, 231 pages]:
Optical design - 6 lenses in 5 groups, type "Mir" / "Flektogon", type of circuit;
Focal length - 22.14 mm;
Relative aperture - 1: 2.8;
Field of view - 64 °;
Frame format - 15 * 22 mm;
The back section is 21.70 mm;
Light transmission coefficient -> 0.68;
Aperture - 8 blades, without a preset mechanism;
Filters thread - absent;
Diameter for smooth tips - 31 mm.
Design and adaptation features
The lens can usually be found in the aftermarket as a lens unit with an aperture without a focusing mechanism. Since OKS1-22-1 has a small back segment, it can be fully used only on mirrorless cameras, while the lens covers a frame of no more than APS-C format.
For adaptation, it is convenient to use the Industar-50 rangefinder focuser, which must first be bored a little from the inside. In this case, the lens unit is attached to the focuser by means of a diaphragm ring - after adaptation, to change the aperture, it is required to turn the lens unit by the nose, which is perhaps even more convenient than it was originally intended.
OKS1-22-1 does not have a thread for filters and covers, but its front lens definitely needs protection. I solved this problem by fixing the Industar-61L / D body part on the nose of the lens with three screws and gluing an empty frame from the 40,5 mm filter into it. Later, he marked the aperture scale on the ribbed focusing ring.
The adapted lens is no larger than an ordinary Jupiter-8 in dimensions, but, unlike it, the OKS1-22-1 has a rear lens protruding beyond the thread, which is easy to stain, even though it is small.
Due to the primitive design of the Industar-50 helicoid, the entire lens unit rotates during focusing. Moreover, the same happens when the aperture is changed due to the chosen adaptation method - in a word, it will not be very convenient to use field filters.
OKS1-22-1 has optics with single-layer antireflection coating of blue and blue shades - which is very typical for almost all LOMO optics (from T-43 to monstrous 70KP projectors). The light transmission of the lens has a maximum in the yellow-green area. In other words, OKS1-22-1 should warm up the picture.
The lens diaphragm has 8 blades - dark, but not frosted. The inner space of the lens unit also has a somewhat dubious blackening. The shape of the hole when closing the diaphragm is a regular octagon with rounded corners. The diaphragm can be closed completely.
In general, OKS1-22-1 pretends to be a compact wide-angle lens, which you can always take with you - there are few such lenses among old lenses. But the applicability of the lens, in addition to the basic parameters and ergonomics, also depends on the optical quality.
OKS1-22-1 uses an optical scheme identical to the Mir-1 37 / 2.8 lens, i.e. is a retrofocus version of a double gauss. Therefore, the lens has good resolution in the center of the frame from an open aperture, however, it quickly decreases towards the edge due to coma and, possibly, curvature of the field. Along the APS-C frame field, good resolution is achieved only at F / 8-F / 11, and the lens does not cover the full frame: it gives a circle with black fields.
OKS1-22-1 works well at close distances, and it is often used for macro photography, especially upside down. This use is encouraged by the large depth of field and high resolution in the center of the frame.
At infinity and on the APS-C, there is a noticeable vignette. When shooting architecture, simple barrel distortion comes out well.
The contrast of the generated image can be considered satisfactory under normal lighting conditions, but in the backlight it drops dramatically, whole chains of glare, "sunny rain" and a dense veil appear. In a word, it is difficult to use OKS1-22-1 against the sun - the enlightenment of optics and blackening of parts used at LOMO are ineffective.
Thanks to its optical design, OKS1-22-1 has a pleasant "helios" bokeh, which appears only when shooting at close distances due to a small aperture: circles of confusion closer to the edges of the frame turn into lemon with a light border, which creates a vortex effect.
Sample photos taken with the full-frame Sony A7s are shown below. Part of the photo was taken in full sensor (left without cropping or with manual cropping), part - in APS-C mode. The survey was performed in RAW with subsequent processing in Imaging Edge.
OKS1-22-1 22 / 2.8 is a rather weak optical lens, which, however, provides a large field of view even on a crop with a modest size. In skilled hands, OKS1-22-1 can serve as a good macro lens. But, nevertheless, if possible, it is better to take a closer look at modern Chinese 25 / 1.8 lenses, for example PERGEAR 25mm 1: 1.8 HD.MC.
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