lightseeker.org / Lichtsucher.com: The Porst Weitwinkel auto F 35mm f/2.8

Porst, like Revue, was not a camera maker, but Germany's largest photographic studio, where everything began with a small photo business in 1919. Porst was also strongly represented in the mail-order business. Porst was produced by various manufacturers at home and abroad. Strongly represented here were also cameras from the GDR and the USSR. After the bankruptcy in 2002 the name came to the Ringfoto group.

Which company the Porst wide angle 35mm f / 2.8 originally manufactured, unfortunately can not be verified. Probably it was Cosina or Yashica. I have at home a Yashica 35mm f / 2.8, which looks very similar to the Porst lens. However, the two lenses are distinguished by some essential details: the Yashica's close-up limit is very good 35 cm, and the Porst is only 50 cm. The optical performance is also very different. While the Yashica has an excellent sharpness at open-aperture, the Porst is rather milky and slightly blurred. Really sharp the Porst is actually only from aperture 4.0, at least in the center of the photo.
The Porst Weitwinkelauto F 35mm f/2.8 (left) and the Yashica ML 35mm f/2.8 (right):

Specifications:

M42-mount and Pentax K-Mount. My specimen is an M-42 mounted lens.
Focal length: 35mm (Prime-lens)
Max./Min. aperture f/2.8- f/22
Blades 6
Min. Focus 0,5m
Filter Ø 55mm
Weight 210gr. / 7,4 oz
Length 60mm / 2,4 in

The haptics of the Porst is, as with all old lenses, very good. Everything is made of metal and can be moved easily and smoothly. Since the M42 adapter is very wide, the combination of camera and lens considerably increases. Nevertheless, you can handle the camera with the lens still well.
As already written, the Porst 35mm f/2.8 with aperture is very soft and you has dear distress to adjust the right sharpness. Even if the focus peaking to the highest level, you must turn long and try until the sharpness is correct. So I know a behavior only from my Makinon - cucumber. If you stopped down, for example to aperture 4.0, the sharpness and the picture contrast will be better.
If you can take a lot of time and patience for a photo, then sometimes sharp shots can be achieved even with open aperture.

Sony a6000 with Porst 35mm f/2.8 at f/2.8, 1/125s, ISO 100

Sony a6000 with Porst 35mm f/2.8 at f/2.8, 1/60s, ISO 100

Farther stopped down of the lens brings in my opinion no improvement of the picture quality. On the contrary, from aperture 11 the photos become considerably blurred and milky by diffraction losses.
When the aperture is open, the lens is quite sensitive to light. The photography is then over-radiated and pale. Lightly stopped down to f/2.8 or f/4.0 is helpful.

Sony a6000 with Porst 35mm f/2.8 at f/2.8, 1/2000s, ISO 100

Let's summarize: the lens has an excellent construction of full metal, is very well balanced and can be used well. The image quality is poor with open aperture. Stopped down to f/4.0 you can expect a good sharpness and contrast. For obscure reasons it is difficult for the user - even with focus peaking - to adjust the correct sharpness. Sometimes it succeeds, but often you have to turn and turn around the focus ring before the picture is satisfactory. Such a strange lens as this Porst I had never in my hands. The picture quality varies between completely creepy to super great.

Sony a6000 with Porst 35mm f/2.8 at f/2.8, 1/320s, ISO 100

Sony a6000 with Porst 35mm f/2.8 at f/2.8, 1/320s, ISO 100 (100% Crop from photo above)

What should I finally recommend? I dont know. Probably it depends on which specimen you just get caught. The manufacturing quality seems to be very variable. Just try before buying it and buy it only if the picture quality is right away.
Here are some photos that I shot in the last days.