Review Pentakta 2.8 (2) / 30 specially for Radozhiva prepared Rodion Eshmakov (instagram).
Pentakta 2.8 (2) / 30 lens adapted for Sony E. increase.
The Pentakta 2.8 / 30 is a microfiche lens from the Pentakta L100 projection apparatus manufactured by VEB Pentacon in the GDR. Microfiche is a kind of microfilm, in which frames (photographic reproduction of documents with a reduction of ~ 30-60 times) are arranged in the form of a matrix-table in several rows. Optics of the Carl Zeiss Dokumar and, apparently, Tevidon series, which have a very, very high resolution, were used for microfilming in the GDR. Thus, the Pentakta must also be a high-resolution lens, otherwise reading microfilms would be impossible. This feature and attractive basic parameters make this small lens promising for photography today.
Specifications:
Optical design - 6 lenses in 4 groups, Planar;
Focal length - 30 mm;
Relative aperture - 1: 2 (from the factory, a constant aperture is installed, limiting to F / 2.8);
Covers format - up to APS-C;
Features - a projection lens, does not have a focusing mechanism and an iris diaphragm.
Design and adaptation features
The lens is very compact and easily fits into Soviet Mir-1 and Industar-61 helicoids (rangefinder). It will be a little more difficult to install it in the Industar-50 case. The rear section of the Pentakta is quite small - therefore it can only be used on mirrorless cameras, moreover, with a sensor of no more than APS-C format. On these cameras, the lens will be equivalent in angle of view and depth of field to a standard 45 / 2.8 lens. For the alteration, I used the Industar-61 helicoid with minimal changes (the infinity stopper was removed and the rangefinder pusher was removed), in this version I was able to achieve compatibility with the Sony E mount, but not with the M39 * 28,8 threaded mount.
Pentakta in the Industar-61 building.
With the help of a turner, it was possible to install a seven-blade diaphragm from Industar-50 into this small lens unit, which ideally fit the size of the hole, thereby "opening" the lens to the calculated aperture of F / 2. Adjustment of the aperture in the range of F / 2-F / 8 is carried out in this variant by turning the front part of the lens unit with the title ring. It was the installation of the aperture that required reducing the flange of the lens to the length of the Sony E mount.
The Industar-50 diaphragm feels great in the Pentakta 30/2 lens unit (now!).
Naturally, the lens was completely disassembled to work on the body. It is important to note here that if the front Pentakta lens unit uses a conventional screw mount, the rear lens unit is attached with 3 screws, similar to the Domiplan 50 / 2.8 rear lens. Therefore, it is required to pay special attention to the alignment of the rear lens unit to achieve alignment when assembling the lens, otherwise all the efforts of German opticians will be wasted.
Optics Pentakta has the usual single-layer coating of violet shades, but one cannot blame it for noticeable yellowness in the light.
Enlightenment color Pentakta 30/2.
This is not to say that full adaptation of this small lens is very simple - installing an aperture in this lens requires either turning work or an alternative lens housing. Even simple disassembly of the lens unit may require an alignment procedure later on. At the same time, there is no problem finding a focusing mechanism due to the small diameter of the body. However, it is with the diaphragm that the Pentakta becomes a really interesting lens in terms of parameters: compact, fast and rather "wide".
Optical properties
The Pentakta lives up to its purpose and already at F / 2 shows excellent sharpness in the center of the frame. Of course, towards the edges of the frame, the result deteriorates due to the coma characteristic of planar type lenses. Vignetting is present in the F / 2-F / 2.8 range. The best image quality (in field) on the APS-C sensor is achieved at f / 5.6-f / 8.
The contrast of the generated image under normal lighting conditions is very good, with hard backlighting it decreases, and purple reflections appear. In general, the light resistance can be assessed as very good for a single-coated lens.
The recognizable yet unobtrusive bokeh of the Pentakta reminds Tevidonovskoe - this lens is also a perfectly corrected planar. The circles of confusion have an almost uniform distribution of brightness, closer to the edge of the frame, due to vignetting, they turn into characteristic "lemon" - almost symmetrical due to the insignificant effect of coma (unlike, for example, Helios).
The rear focal length of this lens is large enough not to cause color shift problems on modern fine pixel cameras.
Below are examples of photos taken with Sony A7s (APS-C mode, shooting in RAW, processing in Imaging Edge).
Conclusions
This small projection lens isn't easy to adapt, but you can be sure that the results will be worth the effort. For owners of mirrorless cameras of the APS-C format, the Pentakta 30/2 can be a real boon, as it has convenient parameters and excellent optical quality.
You will find more reviews from readers of Radozhiva here.
I have a couple of these, it is better not to disassemble, then you will not adjust,
"I'm talking a lot" (c), but the picture is really nice
It is a very positive practice, which many "testers" adhere to when uploading RAW test files, as they show all the features of the lens much better. It would not be bad to make this mandatory.
If, when the diaphragm changes, the first lens unit rotates along the thread, then the longitudinal gap between the front and rear lens units is violated ??? This is already a "creative" lens.
In mine, I inserted a turned diaphragm from the I-50 and through a groove in the body brought its control to the bushing with the name (I have this version of PENTAKTA 2,8 / 30). When changing the aperture, the lenses do not rotate, centering and longitudinal clearances are not violated. I measured the relative aperture, at open 2,2 it falls short of two.
The first lens unit in my design does not rotate by aperture. The decorative part rotates.