[newmikey]

I had a unique chance to obtain both the Porst as well as the Revuenon 55mm/f1.2 lenses via eBay. In the short time I have used both I can already provide the below impressions.

Build:
The Porst is a solidly built lens, all metal with a black anodized lensmount (more on that below). The Reveunon is also all-metal but has a blank-metal mount. Both have unusually large rear elements obviously requiredbecause of the large maximum aperture of f1.2

Glass:
On both lenses, the front element is quite large as well but the Porst one is slightly more recessed than the Revuenon. Nevertheless it seems the Porst is slightly more susceptibe to contrast reduction on account of stray light hitting the front element and I have immediately supplemented the Porst with a metal lenshood which visibly improves the contrast. I have also ordered a similar hood (58mm thread instead of the 55mm for the Porst) for the Revuenon but that is more to protect the front element from harm as its contrast is already quite decent even at full opening.

Available exposure modes:
Of course both are manual lenses without AF connector or electronic contacts. At max aperture both function as expected in M as well as Av mode.
As the Porst lensmount is non-conductive and does not short out two contact on the lensbody, the green button does not work but a small piece of conductive material stuck between lens and mount solves that (I use a piece of the inner wrapping of a pack of cigarettes). I intend to use a bit of self-adhesive copper tape on the mount as a more permanent solution. Another option would be to open up the mount and remove a little spring but I'm sure that is a bit too drastic for me. The reason to purchase the lens it to use it wide open, otherwise one could equally use any of the AF 1.4 or 1.8 options Pentax offers. (I have the DA50mm/f1.8 - great little gem)

The Revuenon has a conductive mount so can be used with the green button exposure without any modding, the aperture closes and the exposure meter sets a correct shutterspeed.

Image quality:
This where I got somewhat of a surprise. I would have expected both lenses to perform quite similarly but nothing is further from the truth! The Porst delivers a dreamy, almost etheric image at full aperture with halo-like transitions and smooth bokeh. The colours are quite lively and contrast (with a hood) is decent. At smaller aperures the dreamy look disappears and the image gains loads of sharpness and detail. The Revuenon has none of that dreamy-like quality and seems to have a somewhat cooler rendition of colors. Even wide-open at f1.2, the sharp parts of the image are very sharp and with a few stops in, that sharpnes spreads corner to corner. Here too, bokeh is excellent with smooth transitions between sharp and unsharp a creamy OOF circles.

Conclusion:
The two lenses are quite distinctively different, except for the build quality which is excellent in both. Both focusrings turn smoothly and easily, the Porst seems to have a longer throw. For now, I'll be using both with pleasure, one for the dreamy look and the other for the wonderful rendering and sharpness. Evenetually, I'll probably get rid of one as I already have quite a bit of glass and do not need to be caught in indefinite indecision. "There can be only one!".
I can offer two non-scientific examples shot on different days under slightly different lighting conditions. Are you up for a challenge? Which image belongs to which lens?

[narual]

I'd say the first image is the porst, with a hood on. It would be more obvious without the hood because it would have a sort of milky quality to the light that is sometimes pretty, and often annoying. Also, at least on mine, the bokeh doesn't have that small ball effect, it's more streaks

I sanded enough of the black coating off my porst that it reads through. Conductive tape would probably have worked, too, but I was worried about it jamming up.

The hood makes a really huge difference. Did you get one that was long enough? It should be one intended for an 85mm FF lens, if you're using it on a crop sensor. And having focus peaking in live view helps tremendously, as well.

[kaipa]

Excellent analysis and comparison. I owned both lenses in the past (and now still have Tomioka 55/1.2 -- pre-Porst, and Vivitar 55/1.2 -- clone of Revue) and my impressions are similar to yours.

[Stagnant]

Any chance to see the images in full size ?

[LennyBloke]

Thanks for your write-up, interesting to hear your views and even better to back them up with images. - I have a Porst on it's way to me shortly, and I'm hoping your first shot is the one with my soon to be ultra-fast

[Stagnant]

After looking at the full size images, I would say that Revuenon looks a bit sharper and more contrasty.

[narual]

Any chance to see the images in full size ?

For whatever it's worth, I have some porst shots here you should be able to see in full size. They're sorted by date, and I put a hood on it in mid to late 2014.

Porst 55 1.2 Tests | Flickr

The K3 ones are mostly focused using live view with focus peaking, so they'll be a good bit sharper than the ones in the K5, especially the earlier ones before I got an ee-s focusing screen.

[Pioneer]

I have the Tomioka 55/1.2 in M42 and it is an excellent lens. Quite good wide open it becomes exceptional by f4. It does have noticeable vignetting and CA, both of which are gone by f4, at least in practical field photography. Distortions seem pretty well controlled but I haven't photographed any brick walls with it so your mileage could vary. It is one solid lens and everything on it is tight and well damped. I have no reason to believe that it will change during my time with it. This is a lens you pass along to your kids, and then to their kids, and so on. A very, very occasional lube job will likely be all it needs for several lifetimes of use.

Personally I think it is better on film than on digital so I tend to use it more frequently with my Spottie where it performs very, very good. Since it gets used as a walk around lens on the Spottie I use it all the way to f8 and it does really well. A little heavy but it balances nicely on the Spotmatic. I'll take some shots with it at my Grandson's next basketball game and post some relatively low light, indoor action photos from it.

[newmikey]

I have the Tomioka 55/1.2 in M42 and it is an excellent lens. Quite good wide open it becomes exceptional by f4. It does have noticeable vignetting and CA, both of which are gone by f4, at least in practical field photography. Distortions seem pretty well controlled but I haven't photographed any brick walls with it so your mileage could vary. It is one solid lens and everything on it is tight and well damped. I have no reason to believe that it will change during my time with it. This is a lens you pass along to your kids, and then to their kids, and so on. A very, very occasional lube job will likely be all it needs for several lifetimes of use.

There's a lot of confusion but I think your M42 Tomioka is a step up from the later K-bayonet Porst and Revuenon incarnations which seem to have been made by Cosina as far as I have researched. You truly have a gem in your hands there but honesty requires that I clearly state that neither one of my lenses is said to perform as good as the Tomioka-made 55mm's in M42 version.

[kaipa]

There's a lot of confusion but I think your M42 Tomioka is a step up from the later K-bayonet Porst and Revuenon incarnations which seem to have been made by Cosina as far as I have researched. You truly have a gem in your hands there but honesty requires that I clearly state that neither one of my lenses is said to perform as good as the Tomioka-made 55mm's in M42 version.

Since I have Tomioka, I know what it is about )

The story is that m42 Tomioka was the first f1.2 lens for 35mm SLRs. It has been produced under different sub-names (Tomioka Cosinon, Tomioka Revuenon, Tomioka Tominon, Tomioka Chinon and Tomioka Yashinon). There is a good web site dedicated to this lens history: Preload Tomioka e main
I am the proud owner of multi-coated Tomioka Cosinon version, that is one of the rarest.

Later on Tomioka stepped off producing lens by its own name continuing to make glass and lenses as an OEM manufacturer. f1.2 lens design has been bought or licensed by Cosina and produced as K-mount Cosina Cosinon-S lenses and Porst. So, Porst is optically the same lens design as legendary Tomioka, though have lower quality contruction and probably lower quality glass. I tested Porst and Tomioka side by side -- the picture is very close.

Later on, Cosina has developed its own f1.2 design that we can see under names of Revuenon/Cosina/Rokinon/Vivitar in K-mount in two different exteriors. This lens have better contrast, but this plays back negatively in out of focus areas. Tomioka/Porst produce more dreamy images. Rumors say that glass for new Cosina lenses has been produced by Tomioka (actually, I've read it somewhere on the forum, most likely in f1.2 lens club thread https://www.pentaxforums.com/forums/122-lens-clubs/74819-post-your-1-2-photos-1-2-only.html)

So it is all twisted here and there.

[Pioneer]

Thank you kalpa. Very interesting post and link. Now I know much more about my Tomioka lens.

[Stagnant]

For whatever it's worth, I have some porst shots here you should be able to see in full size. They're sorted by date, and I put a hood on it in mid to late 2014.

Porst 55 1.2 Tests | Flickr

The K3 ones are mostly focused using live view with focus peaking, so they'll be a good bit sharper than the ones in the K5, especially the earlier ones before I got an ee-s focusing screen.

Thanks for the link ! There are not that many K-3 shots in the album, but some of the K-5 shots are quite informaitve.

[newmikey]

Later on Tomioka stepped off producing lens by its own name continuing to make glass and lenses as an OEM manufacturer. f1.2 lens design has been bought or licensed by Cosina and produced as K-mount Cosina Cosinon-S lenses and Porst. So, Porst is optically the same lens design as legendary Tomioka, though have lower quality contruction and probably lower quality glass. I tested Porst and Tomioka side by side -- the picture is very close.

That's very encouraging! I had thought of selling off the Porst but I might reconsider now...

Later on, Cosina has developed its own f1.2 design that we can see under names of Revuenon/Cosina/Rokinon/Vivitar in K-mount in two different exteriors. This lens have better contrast, but this plays back negatively in out of focus areas. Tomioka/Porst produce more dreamy images. Rumors say that glass for new Cosina lenses has been produced by Tomioka (actually, I've read it somewhere on the forum, most likely in f1.2 lens club thread
So it is all twisted here and there.

It may be "twisted" but it makes interesting reading nevertheless. The better contrast versus dreamier images issue I had noticed when comparing both lenses side by side. Good to see that observation confirmed!

Thanks for all of that info, much appreciated!

[narual]

Thanks for the link ! There are not that many K-3 shots in the album, but some of the K-5 shots are quite informaitve.

I put a few more up.

It's just more difficult to identify them on the K-3. On the K-5, I'd shorted out the aperture pin on the body so it would play more nicely with manual lenses. It wasn't the best for stopping down since the aperture lever isn't the same on M lenses as it is on A lenses, but I mostly used it with the 55/1.2 lens, at 1.2.

On the K-3, I didn't want to mess with it, so it just shows up as "unknown aperture." Some of the ones I uploaded probably aren't at 1.2. And all that assumes I actually remembered to set the focal length to 55mm in the first place... I probably have a bunch in there at 28mm and 135mm from the other two manual lenses I tend to use.

And of course, I just haven't taken as many photos since I got the K3.

Need to change that. And this lens, in particular.

---------- Post added 10-26-16 at 11:00 AM ----------

Since I have Tomioka, I know what it is about )

The story is that m42 Tomioka was the first f1.2 lens for 35mm SLRs. It has been produced under different sub-names (Tomioka Cosinon, Tomioka Revuenon, Tomioka Tominon, Tomioka Chinon and Tomioka Yashinon). There is a good web site dedicated to this lens history: Preload Tomioka e main
I am the proud owner of multi-coated Tomioka Cosinon version, that is one of the rarest.

Later on Tomioka stepped off producing lens by its own name continuing to make glass and lenses as an OEM manufacturer. f1.2 lens design has been bought or licensed by Cosina and produced as K-mount Cosina Cosinon-S lenses and Porst. So, Porst is optically the same lens design as legendary Tomioka, though have lower quality contruction and probably lower quality glass. I tested Porst and Tomioka side by side -- the picture is very close.

Later on, Cosina has developed its own f1.2 design that we can see under names of Revuenon/Cosina/Rokinon/Vivitar in K-mount in two different exteriors. This lens have better contrast, but this plays back negatively in out of focus areas. Tomioka/Porst produce more dreamy images. Rumors say that glass for new Cosina lenses has been produced by Tomioka (actually, I've read it somewhere on the forum, most likely in f1.2 lens club thread https://www.pentaxforums.com/forums/122-lens-clubs/74819-post-your-1-2-photos-1-2-only.html)

So it is all twisted here and there.

Do recall that there are two different Porst 55/1.2 lenses, as well -- the f/16 and f/22 models.

[kaipa]

Do recall that there are two different Porst 55/1.2 lenses, as well -- the f/16 and f/22 models.

Right. f/16 is similar to Cosina family lens (60cm MDF, 9 diagram blades, 58mm filter thread). f/22 is older Tomioka design (45-50cm MDF, 8 diagram blades, 55m filter thread). There could be some versions in the middle, probably. Older f/22 Porst version is more common.