[rparmar]

Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

---

Amazing stuff!!!!!!!!!!!!!!!

Thanks for that. Though personally I am not fond of this look, I will still keep the lens around for when light is really low. Someday I'll try it with portraits, though I don't do too many of those.

[Peter Zack]

I agree with Javier, those are both very good Robin.

[Ashley_Pomeroy]

"I've concluded that the Porst has a character that showed across different users similarly which was to my liking."

Veering off-topic slightly, and largely as a result of this very thread (it's one of the top Google returns for "porst 55mm f1.2"), I went and bought one of these Porsts. Sadly the other lenses mentioned in the thread aren't readily available on Google at the moment, and I spotted a bargain. It's always nice to have an f1.2 lens, it exudes bigness, and this particular lens looks like a giant glass eye.

Anyway, it's a PK-mount lens that I have hacksawed to fit onto a Canon 5D. I chopped off the aperture pin, the pointy-out Pentax pointy-out prong, and also the ring that protrudes beyond the bayonets. It mounts and works a treat. It doesn't seem much brighter than the 50mm Yashinon f1.4 and Takumar f1.4 I also use, but I haven't had a chance to test it fully. I'll probably take the train to London tomorrow and shoot some sculptures at f1.2, which I can post here if you want. It does seem noticeably soft at f1.2, but I don't mind that effect.

One problem though. The lens focuses and works perfectly except at absolute infinity. One fraction of a twist before infinity it is fine; but at absolute infinity it must be catching on the mirror, because there is a typical dark area on the photograph, and the shutter sound is noticeably slow. I assume that my PK adapter (one of those generic "focus confirm" jobs from eBay) is just fractionally too thin. Does anybody know a good place where I can buy a high-quality PK-EOS adapter?

I apologise if the butchery of this lens has upset people. Nonetheless there are plenty of them about, they seem very well-made by modern standards, far superior to all of Canon's mid-range lenses.

[Peter Zack]

You made up for the hack job on the mount with the following " Nonetheless there are plenty of them about, they seem very well-made by modern standards, far superior to all of Canon's mid-range lenses." As for the adaptor, Ebay? B&H? Not really sure. Post your shots when you can. It would be nice to see.

[thePiRaTE!!]

Hi Ashley. Here's a link to MFlenses camera/manual lens guide for Canons.

Manual Focus Lenses :: View topic - Canon EOS and manual focus lenses

All the research has been done for what lens works with what body, etc. Many lenses do interfere with the mirror, yes. I'm personally not sure about the Porst, but I can say after some more testing that the Yashinon I have is looking more and more like another Porst in a different skin. I'm starting to believe they are the same. The Yashinon is sought after due to it being an M42 lens (no surgery required).

Looking forward to more pics though!


Kelly.

[Bart]

Pirate, some info on these 55mm f/1.2s.

The lens company Tomioka, of Japan, originally designed the 55mm f/1.2 lens for Yashica (whose line of lenses were called Yashinon) in M42 mount. They later went on to produce it for Cosina (Cosinon), Revue (Revuenon), Chinar (Chinon, do you see a trend here?) and with Tomioka's own brand name...wait for it...Tominon. Apparently they also built them for Vivitar (serial # begining with 84), but the only one I've ever seen is on eBay right now. As far as I know, it was never produced in P/KA mount for Pentax, just P/K, but Tomioka did build a 'P' version for Ricoh (Rikenon). I believe Tomioka transitioned off the M42 mount to bayonet mounts in 1974.

The Tomioka 55mm f/1.2 has the following specs:

Focal length: 55mm
Filter size: 58mm
Diaphragm blades: 9
Aperture range: f/1.2 to f/16
Optical formula: 7 elements in 6 groups
Closest focus: 60cm...
--M.

Well the mailman had a present for me today. I took a few test shots with the lens and damn it's fast! It has razor thin DOF when wide open and seems very sharp.

I got it here: Pentax 55mm f/1.2 (1:1.2, f1.2) Cosina (Cosinon) - eBay (item 160293617517 end time Oct-22-08 23:18:12 PDT)

Anyway these are just a couple of quickie test shots since I didn't have much time to use the lens. But well worth it and it's going to be fun to use!.

Metering is the same as all M series lenses, put in in manual mode and I took 4-5 shots in Av just to give it a try. The lens seems consistant and with about -1.7 Ev added in, it seems to expose just fine across the range....

I would like to ask a question about the Cosinon and the Revuenon: would this mean these are the same lenses regarding optical formula and build quality?
What about the coating?

And an additional question about the metering. Peter found a constant -1.7 EV compensation works out but wasn't part of the problem with metering "pre-A" lenses that the compensation was not constant across the aperture range?

[Miserere]

I would like to ask a question about the Cosinon and the Revuenon: would this mean these are the same lenses regarding optical formula and build quality?

As far as I can tell: yes.

What about the coating?

That is a whole 'nother matter. Somebody who has both would be able to (maybe) reply to that, but I doubt anyone has.

And an additional question about the metering. Peter found a constant -1.7 EV compensation works out but wasn't part of the problem with metering "pre-A" lenses that the compensation was not constant across the aperture range?

I haven't used my Cosina in a while (my camera is away for fixing) so I cannot give you a definitive reply. If I remember correctly, metering seemed fine when shooting wide open in Av (some might have said it was overexposing, but images looked like I wanted them to look). When stopping down I think it was pretty constant exposure throughout the aperture range, but darker (faster shutter speed) than I would have expected given the metering wide open. But I'm used to old lenses doing this. In any case, I didn't buy this lens to shoot it at f/8, I wanted it for the F/1.2 so I rarely stopped it down.

When I get my camera back and conduct some serious tests I can get back to you on this. In the meantime, there are plenty of people here with this lens, so maybe one of them will be kind enough to shoot a blank wall at different apertures and let us know what they find

[Ashley_Pomeroy]

Right, I spent Sunday wandering around the V&A, the Natural History Museum, and the Science Museum, with my modified Porst 55mm. The mirror blocking wasn't an issue, because it only happens when the lens is focused beyond infinity, and I will only ever never need to focus beyond infinity at the moment of my death.

I usually took two shots quickly - one at f1.2 and a second one a couple of clicks stopped-down until I felt I couldn't handhold the exposure any more. Looking at the EXIF data, I probably stopped down to f4, but that's not exact. The metering was odd - at f1.2 the images tended to be slightly overexposed, and as I stopped down they became underexposed. Perhaps it's a general characteristic of old lenses with manual adapters.

I've used "auto contrast" but I haven't applied any sharpening. All of the images were taken with a Canon 5D at ISO 1000-1600.

Here's a general shot of Queen Victoria, taken at f1.2:


Here's an example of the vignetting at f1.2 versus stopped down a little:


Here's a demure-looking lady at f2, which is the best aperture to use in my opinion:


Here's a comparison of the relative sharpness at f1.2 and stopped down:


A mean-looking fellow at f2.0:


A creepy girl:


This lady doesn't illustrate anything, she's just nice:


My general impression is that at f1.2 it's really a soft-focus portrait / special effect lens. At f2.0 there's a nice balance of sharpness and blur. It doesn't become normal until f2.8, and beyond that it's no slightly less sharp than my 50mm Yashinon f1.4 at all apertures. For low light situations it's much better to just increase the ISO, but on the other hand the blur at f2.0 is very nice. Also, the vignetting is striking. The lens looks great too, like a gleaming pool of water.

[Ashley_Pomeroy]

While I'm at it, here's a more formal test of the lens (warning: v large):


Compared with the same test shot with a Yashinon DS-M 50mm f1.4, an M42 lens:


As someone points out above, the Porst goes straight from f1.2 to f2.0, with no click stops in between, and has whole stops down to f22.

[Bart]

I haven't used my Cosina in a while (my camera is away for fixing) so I cannot give you a definitive reply. If I remember correctly, metering seemed fine when shooting wide open in Av (some might have said it was overexposing, but images looked like I wanted them to look). When stopping down I think it was pretty constant exposure throughout the aperture range, but darker (faster shutter speed) than I would have expected given the metering wide open. But I'm used to old lenses doing this. In any case, I didn't buy this lens to shoot it at f/8, I wanted it for the F/1.2 so I rarely stopped it down.

When I get my camera back and conduct some serious tests I can get back to you on this. In the meantime, there are plenty of people here with this lens, so maybe one of them will be kind enough to shoot a blank wall at different apertures and let us know what they find

Thanks for your answers Miserere.
You are right of course: the lens isn't really meant to be used stopped down. It's a specialized lens for very specific usage. That's what I ment in Benjikans thread when referring to JensR: ...Or he was looking for other qualities in the lens...

Sorry to hear you are missing your camera. I just hope for your sake it doesn't take them as long as they did with mine. Mine was sent in end of July together with the bulk of my lenses (second attempt) and I still don't have it back .
It is said to be on it's way back now. Just hoping its fixed.

Ps about the shooting a blank wall: shouldn't this be a 18% grey wall?
Should make a great change in the ordinairy brick walls

[Miserere]

Ashley, thanks for those comparisons. The Porst is certainly a softie wide open. It'll be nice to see something similar with the Cosina.

[Gooshin]

dont forget softness is a factor of distance too, seems that Porst shot was pretty damn close, DOF is non existant


here is the Cosina @ f1.2, about 4 feet away from the subject, parallel'ed (90* to the ground)

the focus was made around the eye level of the rat, also the books are actually stacked in a pyramid to
demonstrate DOF changes, each book is about an inch further in as it goes up, the focus was made
on the book with the tittle "БОРИС АКУНИН "АЗАЗЕЛЬ" "

click here for full res

[Miserere]

Sorry to hear you are missing your camera. I just hope for your sake it doesn't take them as long as they did with mine. Mine was sent in end of July together with the bulk of my lenses (second attempt) and I still don't have it back .
It is said to be on it's way back now. Just hoping its fixed.

I really hope it doesn't take that long! My camera is actually also going back. They had it for two weeks, returned it to me only half-fixed, and it spent all of last week in a box waiting to be picked up by UPS, who never came by. I just got off the phone with Pentax customer service and they don't know what happened and will call me back when they do. So I expect to be without a camera for a further 3 weeks, increasing the current total to 6...when it should only have been 2!

[Miserere]

here is the Cosina @ f1.2, about 4 feet away from the subject, parallel'ed (90* to the ground)

I'll have to bring out my collection of Aramaic books to test the Cosina...

[Gooshin]

more wide open shots

this thing is very usable at 1.2!

only thing the specular highlights are somewhat odd, they are half circle/oval shaped, its weird.