Material on the Zenit IR-Tele 2,8 / 135 lens especially for Radozhiva prepared Rodion Eshmakov.
Zenit IR-Tele 2,8/135 lens. increase.
The lens was provided by Alexander Korolev especially for the review (Inst: revvoensovet).
This article presents a lens that has never been designed for cameras - a lens from a night vision device (NVD) Zenit IR-Tele 2,8 / 135 manufactured by KMZ. Because NVD image intensifier tubes are sensitive to the visible orange to near-infrared spectrum, the optics for use with them are generally not designed to operate in the short-wavelength visible spectrum and therefore produce a rather unusual image on conventional cameras.
Other reviews of night vision lenses adapted for use with conventional cameras:
- 50mm f/1.5 lens of the tank binocular TVNO-2B (IPZ, Izyum, Ukraine)
- 50mm f/1.2 lens of the tank binocular TVNE-4B (IPZ, Izyum, Ukraine)
- 37mm f/1.0 lens of night vision goggles PNV-57E (LZOS, Lytkarino, RF)
- 130mm f/1.8 mirror-lens lens PNV Cathod-MNV (refinery, Novosibirsk, RF)
Specifications (according to the KMZ documentation and patent RU2047200C1):
Optical design - 5 lenses in 4 groups;
Principal optical diagram of the lens (RU2047200C1). In fact, surface 6 is flat.
Focal length - 135 mm;
Relative aperture - 1: 2.8;
Spectral range - 680–880 nm;
Diaphragm design - 8 blades, stepless;
Linear field of view (calculated) - 18 mm (covers APS-H without vignette, and full frame - when focusing on MDF);
Mount - M42 (rear focal length ~ 36 mm does not allow to achieve infinity focusing on full-frame SLR cameras);
The minimum focusing distance is 5 m;
Dimensions - 57 x 91.5 mm;
Weight - 0.5 kg;
Features - internal focusing.
Design features
Zenit IR-Tele 2,8 / 135 (hereinafter referred to as simply Zenit IR) is made in a body that is functionally similar to conventional photographic lenses: there are quite familiar focus control rings and aperture settings, moreover, rubberized. The only caveat is that there are no familiar marks on the aperture scale on the aperture scale, but only an indication of the “brighter-dimmer” type.
External view of the Zenit IR lens body.
The iris diaphragm of the lens itself consists of 8 petals and forms a “circular saw” pupil when closing.
View of the lens pupil at aperture ~F / 5.6.
View of the lens pupil at aperture ~F / 4.
View of the pupil of the lens at an open aperture.
As you can see, the lens turns very yellow through the light - this is due to a special single-layer anti-reflection coating that provides maximum light transmission in the red region of the spectrum, but reflects blue light - very similar to the coating used in TVNO-2B 50/1.5.
A feature of the lens is internal focusing. The lens mounted on the camera does not change its dimensions when focusing, only the rear lens moves, and not the entire lens block. However, this method of focusing in simple optical designs can greatly affect image quality, especially at the edges of the frame. It is for this reason that the Zenit IR has a very large minimum focusing distance of as much as 5 meters.
View of the lens from the side of the rear lens when focusing at infinity.
View of the lens from the side of the rear lens when focusing on MDF 5 m.
By itself, the rear lens of the lens, when focusing to infinity, strongly protrudes beyond the M42 mount (exactly the same as for Zenith cameras). It can hook the mirror on full-frame SLR cameras. Moreover, the size of the rear lens of the lens is too small to cover the 36x24mm matrix well.
View of the rear lens and Zenit IR lens mount.
There are no particular complaints about the build quality and performance of the lens, although it is clear that the focusing method used is connected only with the desire to simplify and reduce the cost of the design. It is also worth noting the problem, traditional for Soviet / post-Soviet optics, with the quality of the blackening of the spaces between the lenses.
Optical properties
I had the opportunity to test the Zenit-IR lens only in the visible range (400-700 nm), since there was no full-spectrum camera in stock. In general, the image quality on a conventional camera can be assessed as unsatisfactory at any aperture set due to the strongest longitudinal chromatic aberrations - the lens is completely not designed to work in the visible spectrum. The best results can be achieved when shooting subjects that do not have a blue part of the spectrum, which is, oddly enough, portrait photos taken with this lens look satisfactory.
On a full frame camera, the lens vignettes heavily when focusing at infinity. Aperture only exacerbates the effect. To get around this problem, you can use a lens on a mirrorless camera with an adapter equipped with its own helicoid - in this case, you can mount the lens on a 5m MDF and focus it with a second helicoid to infinity, thereby avoiding strong vignette. Below are examples of photos on a covered aperture (about F / 5.6), illustrating this effect on the Sony A7s.
Photo taken with the Zenit IR with the focus mechanism set to infinity.
Photos on Zenit IR taken with the focusing mechanism set at ~10 m with focus compensation with an additional helicoid
At closer ranges, the effect is less pronounced, with vignetting contributing significantly to the shape of the lens' bokeh.
Photo taken with the Zenit IR with the focus mechanism set to infinity.
Photos on Zenit IR taken with the focusing mechanism set at 5 m with focus compensation with an additional helicoid
The color reproduction of a lens is highly distorted by both light transmission and light scattering on glass-to-air surfaces. The resulting image has a yellow tint, but in the backlight, a dense blue veil often also appears, which creates an unusual combination of complementary colors in the frame. At the same time, the image contrast is low, in the backlight it is low.
In the visible region of the spectrum, the lens has an expressive bokeh. Out-of-focus discs have bright orange fringing due to the effect of chromatic aberration. Because of the vignetting along the edge of the frame, the discs turn into characteristic "lemons".
Since the optical design of the lens is known and published in patent RU2047200C1, I simulated its optical properties in ANSYS Zemax 13 software to clarify the behavior of the lens in the visible region (400-700 nm, RGB spectral function of CMOS camera matrices) and in the range of 600-900 nm (orange - near IR).
Diagrams of aberration spots in the focal plane (upper left), during defocusing (lower left) and a longitudinal chromatic aberration diagram (lower right) for a Zenit IR lens in the visible spectral range of 400-700 nm (modified spectral function of the Sony A7M2 sensor).
Diagrams of aberration spots in the focal plane (upper left), during defocusing (lower left) and a longitudinal chromatic aberration diagram (lower right) for a Zenit IR lens in the visible spectral range of 600-900 nm with equal weights.
As you can see, in the calculated spectral range, the lens forms an image of quite acceptable quality both on the axis and in the field. However, in the visible region, the sizes of aberration spots increase by a factor of ~4–6, as well as chromatic aberration.
The following are sample photos taken with the Sony A7s full frame camera.
It seemed to me that many of the photos taken with this lens look interesting in black and white. Below are some of them.
Update
Shared unusual photos with Zenit IR 135/2.8 and Sony NEX-3 converted into a full-spectrum camera @concrete walls Sergey Shcherbakov.
Zenit IR 135/2.8 lens on a converted Sony NEX-3 full-spectrum camera with IR filter Zomei 720 nm
Was used for shooting Zomei IR filter 720 nm (does not transmit light with wavelengths shorter than 720 nm - i.e. most of the visible spectrum). The color gamut (“false color”) of photographs is determined by the different sensitivity of the matrix subpixels to long-wave radiation. Under the indicated shooting conditions, the lens is superior in image quality to the Jupiter-37A, including at an open aperture.
Conclusions
Zenit IR-Tele 2,8/135 is a highly specialized lens not intended for conventional cameras. In the visible spectrum, it forms an interesting, but extremely low-quality image, while Zenit IR-Tele 2,8 / 135 fits very well for shooting in the IR range.
You will find more reviews from readers of Radozhiva here.
I had this lens.
This lens is only interesting for shooting in the IR range.
But in amateur photography, only black-and-white shots taken through an orange or light red light filter on a crop had decent quality.
Cool. Strong longitudinal HA and soft make the picture look like monocles, but better, because there is still some kind of sharpness zone. And the color rendering curve gives a very strong retro effect a la budget perestroika cinema.
The photo from the New Gate is not nearly similar to the photography, the glare with a monocle. Try with the right monocle to take the head of a person from a distance of 5 meters and equalize with photographs posted here, like having created Rodion. This is more likely not a soft, but a super-small optical attachment (with b/w). I don’t say anything about the colors, everything is visible and so. The author gave an assessment to the visnovkas. Signs from a new one tell me my child photo for Shift 8m, if it doesn’t hit sharpness, but not a photo from a monocle))
Wanting for taste and color water near the skin swamp is rich)
I'll try to take pictures at IR 720 and 850 nm on this glass on the weekend and throw it on.
Arkadiy, animal respect, hyperlinks entangled 50 1.2 and 35 1.0.
Tsikavo, what are the bravados looking at, having read the name of the place Izyum?
Fixed
But isn’t there still the Internet, letters and reading weren’t forbidden?
Review from Russia came if I'm not mistaken
this is wonderful, at their own expense they are beaten
Interestingly, nowhere in the reviews are there any photographs of this lens, but of a full-spectrum camera with an IR filter.
I will correct this annoying oversight.
Here's a photo of it for you, the aperture is always about 5.6 - 8, the filter is 720 nm.
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Maybe send Arkady an archive with photos and add them to the review with a link to you? I wouldn't mind.
Come on, I can even attach a small review from myself to the photo. But where should I write to him?
If you also want to add some text, I suggest doing it as an addition to this. You can send me an email: rudzil@yandex.ru, or write on social media. I'll give the material to Arkady if everything is OK.
Good and high-quality images were obtained in the IR range.