The first version of the I-26M differs noticeably from the second one, the lens body is rounded and has a characteristic leash on the side (sometimes this lens is called "leash"). Even in the first and early second versions, a red letter "P" flaunts on the ring with the name, it indicates that the optics are enlightened (single-layer enlightenment). The latter do not have such a letter, but this does not mean that the optics are not coated (some people think so), the coating is applied by default (as multi-layer MC coating is not written on modern lenses, but it is there).
- Focal length 52mm.
- The maximum aperture is 2.8.
- The minimum aperture is 16.
- The number of aperture blades is 10.
- The number of lenses / groups is 4/3.
- The minimum focusing distance is 1 meter.
- Center / edge resolution - 30/12 lines / mm.
- Light transmission - 80%.
- Working distance -28.8 mm.
- Attachment for attachments - threaded m 40.5.
- Optics mount - m39.
- Weight -100 grams (option 1) 120 grams (option 2).
Ergonomics and design:
The first version of the I-26m (with a leash) in terms of ergonomics is not much different from the early copy, except for the focusing ring. In the later (read the second) specimen, the focusing ring is much larger and has a conical shape with characteristic lugs that prevent fingers from slipping. Actually the same body, with a tapered focusing ring, was transferred to Industar-61 l / D.
The travel of the helicoid takes half a turn - about 180 °, this value is common for all 50 mm rangefinder lenses made in the USSR, this is caused by the correct connection of the rangefinder pusher with the leash (at other focal lengths the travel should be more or less). For frequent lubrication in the helicoid for half a century, it loses its properties and turns into dirt, which is why the focusing ring travel is too tight and moves in jerks, or, on the contrary, is too light. Complicating the focusing process is that the focus ring is too close to the camera, the fingers bend excessively and there is a slight feeling of discomfort. There is no such problem on mirrorless cameras, the adapter ring is thick enough and the lens focusing ring is located a little further.
The ring responsible for controlling the aperture is located in the nose of the lens, closing or opening the aperture occurs smoothly - without clicks and steps. Ten (!) Blackened petals form a round hole at any aperture value.
The M39 threaded connection is universal and common for rangefinder and SLR cameras (Zenith, Zenit-3, etc.), but the focal length of rangefinder lenses is much smaller, 28.8 mm. The I-26M lens can be attached to digital SLR cameras using an adapter, but focusing at infinity will be impossible, the macro mode is exclusive. Full lens operation will be possible on mirrorless cameras (except for Pentax K-01).
Everyone expects sharpness and total detail from the optical scheme of Tessar, while Industar-26m, despite its relationship with the legend, does not have the same optical advantages. At an open aperture of 2.8, the lens has low contrast, in the center there is some hint of sharpness, but terrible soap around the edges.
The trouble is with the color, on the open all the colors are mixed into a porridge, especially when the light is hard. Another thing is when you shoot in black and white, the drop in contrast and resolution is not so noticeable, respectively, there are fewer problems with color, although the halftones are still not expressive.
In counter, Industar-26m is not capable of working at all, except 5.6 higher. A total drop in performance.
In soft lighting and in the rare case of 2.8 aperture, you can achieve a normal result.
Normal operation of the lens is possible at apertures of 4.0-5.6. A quite intelligible sharpness appears, soap disappears along the edges, the contrast is tightened, the color rendition acquires the correct shades.