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Helios lens

Industar-69 2.8 / 28 wide-angle lens for system mirrorless camera

Standard lens for scale cameras Chaika, Chaika-2, Chaika-2M, Chaika-3. The lens is designed for a frame size of 18X24 mm, that is, half a frame. The first Chaika camera had a non-removable lens, the subsequent wide-angle Industar received a M39 threaded connection and its focal distance of 27.5 1. The I-69 is of great interest to owners of mirrorless system cameras Olympus and Panasonic. Since the above voiced cameras have a matrix that does not exceed half a frame.

The first attempts to put the lens on a camera with a large frame size were made back in the days of the film era, FED and Zorkiy showed eerie vignetting at the corners of the frame and a sad drop in resolution at the edges of the frame. With the advent of the Sony A7 mirrorless camera, attempts to put the lens on FF (full frame) were resumed, and Industar-69 was also successfully tested on mirrorless cameras with an APS-C matrix format (crop 1.5).

Specifications:

  • Focal length -28 mm.
  • The maximum aperture is 2.8.
  • The minimum aperture is 16.
  • Aperture blades -5.
  • The number of lenses / groups is 4/3.
  • Minimum focusing distance (MDF) - 0.65m.
  • The angle of view is 56 °.
  • The working distance is 27.5 mm.
  • Threaded mounting type - m39.
  • The type of enlightenment is single-layer.

The design and ergonomics of the wide-angle pancake:

A thin lens - these are usually called pancakes, in fact it is not surprising - the optical scheme of the I-69 has only four elements. Most of the lens barrel is the focusing ring. The diaphragm setting ring is located on the front, which is not very convenient.


Optics mount:

m39 is a universal mount for many cameras, including Chaika-2, 2M, 3. But as mentioned above, the flange distance differs from the rangefinder 28.8 mm by 1.3 mm (27.5 mm for the industrial-69). Therefore, there will be no infinity with the m39 / "your mirrorless" adapter, in order to catch infinity you need to do a simple operation.


1. Set the lens to infinity, unscrew three screws on the sides.



2. access to two limiters will open, the one opposite to the infinity mark (approximately) we do not touch.


3. Unscrew the far stopper. This is done to get a shorter minimum focusing distance.



4. We put the focusing ring in place, but not in the infinity position, but at the minimum distance, without moving the helicoid. Next, we catch infinity

After this procedure, you can fully use the industrial-69 lens with the M39 / "your mirrorless" adapter.

Artistic qualities, photo:

The optical scheme of Industar-69 repeats the scheme of Tessar, the character of the picture is appropriate. But if at 1/2 crop the picture as a whole at an open aperture of 2.8 is acceptable, then already at a larger size of the matrix the edges and corners of the photo are terrible. First, in the corners, a vignette with a purple tint is immediately striking. Secondly, the edges of the frame are soapy, that is, completely. The center is more or less normal when focusing on close-ups in the aisles of 3-4 meters, at infinity you can use an open aperture only for the sake of accurate focusing and cover it at least to f -4.0 before shooting.




Working apertures start at F-5.6, although for the sake of clarity, a couple of frames at 4.0 - the sharpness is higher, the edges are more distinct and the vignette in the corners is not so striking.





Actually at infinity and f-4.0, the picture does not shine and cover up to 5.6-8.0 is simply necessary. Although again in the near shots the sharpness in the center is good, across the field it is acceptable and at the edges I would like to be better.



When shooting architectural ensembles, you can observe the distortion, otherwise the so-called "barrel", the corners of the frame are noticeably stretched. Subjectively, the kick effect is enhanced by the vignette.
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