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01-29-2014, 12:36 AM   #1
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Porst Color Reflex MC Auto 55mm 1.2

Hello all! I've just received my Porst 55mm 1.2 lens. Been playing around with it for a bit and its starting to grow on me.

I've heard a few things regarding aluminum tape, scraping black paint or removing certain aperture rings to get the lens to function in AV mode, but I can't seem to find any detailed information.

Any help would be hugely appreciated.
Thanx!

01-29-2014, 12:59 AM - 1 Like   #2
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I have the same lens. And I love it. If I compare it to my Pentax 50 1.2, the colour rendering of the Porst is worse, almost desaturated, but the sharpness is slightly better.

I didn't have the guts to scrape off paint, the bits might go in all the wrong places. The aperture lever ring can easily be taken out. (And, what was important to me, just as easily be placed back in again.) Just screw off the lens mount and then the ring becomes accessable. This makes the lens usable in AV mode, constantly metering without using the green button.
01-29-2014, 01:45 AM   #3
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Ah... I see, I think. This sounds simular to a modificationI just did for Oly Zuiko 24mm.
So, remove the mount, 4 screws, yes? Then simply remove the aperture ring? Then replace the mount?
Sounds simple enough, will try tomorrow.

Let me know if I've got this correct.
Thanks a bunch, Clavius!
01-29-2014, 02:23 AM - 1 Like   #4
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QuoteOriginally posted by strangeboy Quote
Ah... I see, I think. This sounds simular to a modificationI just did for Oly Zuiko 24mm.
So, remove the mount, 4 screws, yes? Then simply remove the aperture ring? Then replace the mount?
Sounds simple enough, will try tomorrow.

Let me know if I've got this correct.
Thanks a bunch, Clavius!
Yes, that's it. There's also a little spring that you will need to unhook.

There are different versions of it though. They might differ.

01-29-2014, 11:32 PM   #5
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QuoteOriginally posted by Clavius Quote
Yes, that's it. There's also a little spring that you will need to unhook.

There are different versions of it though. They might differ.
Thank you, again, Clavius.
Simple mod. It all works perfectly and my Porst is bangin' in AV mode.
01-30-2014, 03:16 AM   #6
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QuoteOriginally posted by strangeboy Quote
Thank you, again, Clavius.
Simple mod. It all works perfectly and my Porst is bangin' in AV mode.
Glad it worked out ok. Do you have a hood for it? It benefits grately from one. I know, it looks much cooler without a hood, but still.
10-23-2014, 07:20 AM   #7
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I read that this lens do not allows the focus confirmation. If I understand correctly, this means that no green hexagon focus confirmation indicator appears?

In manual mode, the green button metering is ok with this lens?

Thanks

10-23-2014, 07:30 AM   #8
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QuoteOriginally posted by edri Quote
I read that this lens do not allows the focus confirmation. If I understand correctly, this means that no green hexagon focus confirmation indicator appears?

In manual mode, the green button metering is ok with this lens?

Thanks
Green button (stop down metering) is not reliable on this lens. Read the comments from the beginning. You'll want to remove the back then remove the inside ring and spring, then replace the back. You can use the lens quite nicely in AV mode.
10-23-2014, 10:15 AM   #9
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Thanks for the reply.
I still do not understand why pressing the green button the aperture lever do not stop down the lens for exposure measuring.
What is different from the usual PK mount ?

How to use this lens without these changes (removing the ring and the spring)?
10-23-2014, 10:41 AM   #10
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QuoteOriginally posted by edri Quote
Thanks for the reply.
I still do not understand why pressing the green button the aperture lever do not stop down the lens for exposure measuring.
What is different from the usual PK mount ?

How to use this lens without these changes (removing the ring and the spring)?
I'm not exactly sure, but my attempts to use the Green button metering and the attempts of others who own this lens all resulted in spotty performance. Sometimes it worked, sometimes it didn't. Modifying the lens takes about 10 or 15 minutes and is completely reversible. Then you'll have a lens that meters without any extra steps. I don't know what else to tell you.
10-23-2014, 02:32 PM   #11
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Hm. Maybe I should do that. I sanded the paint off on mine, and have a tiny piece of foil tape shorting the A sensor on my K5 so it thinks every manual lens is an A. It makes non-wide-open shots a bit iffy (I say F/4, lens is really f/8 or something). A hood definitely helps. I picked up an inexpensive screw-in metal hood intended for an 85mm. There's a tiny big of vignetting (just dimming of the corners, not actual blacking out) with it, probably since the 55mm equates to more like an 82mm, but that's not a big deal. Even with the hood, though, it's not the sharpest lens I own by any means. Wide open, in sunlight, everything's just a little bit 'dreamy', but stopped down a bit, that goes away.
10-23-2014, 02:48 PM   #12
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Porst 55mm f/1.2

I shot this earlier today... gotta allow for forums compression, though.


These a couple of weeks ago:



Last edited by strangeboy; 10-23-2014 at 02:53 PM.
10-23-2014, 11:53 PM   #13
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Wow. I was undecided whether to buy such a lens. Now I want one.
Some people say that they can not get sharp photos in daylight. Surprisingly clear first photo. Impressive bokeh for the other two.


Now I think I understand the problem. it is inconsistent exposure without modification of the back lens.
thought it was something mechanical and pressing the green button does not move the aperture lever.

What about focus confirmation at f1.2? The green hexagon appears to confirm manual focus (lens without modification)?

---------- Post added 10-24-2014 at 08:28 AM ----------

QuoteOriginally posted by narual Quote
Hm. Maybe I should do that. I sanded the paint off on mine, and have a tiny piece of foil tape shorting the A sensor on my K5 so it thinks every manual lens is an A. It makes non-wide-open shots a bit iffy (I say F/4, lens is really f/8 or something). A hood definitely helps. I picked up an inexpensive screw-in metal hood intended for an 85mm. There's a tiny big of vignetting (just dimming of the corners, not actual blacking out) with it, probably since the 55mm equates to more like an 82mm, but that's not a big deal. Even with the hood, though, it's not the sharpest lens I own by any means. Wide open, in sunlight, everything's just a little bit 'dreamy', but stopped down a bit, that goes away.
Thanks. For this dreamy effect a want this lens.
What is the difference in using the lens after sanded the paint?
10-24-2014, 07:38 AM   #14
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What aperture were those shot at? Doesn't look like 1.2.

The dreamy blah blah is mostly present in color. It goes away a bit converted to black and white.

When you sand off paint on a lens it allows the pins on the camera to touch bare metal. In depth description of what those do here: Features and Operation of the Ka Mount

You can sand just the specific pin locations for the lens aperture range. In the case of my porst, at least, that's all of them (1.2-22 range). On another lens I have, the range is 3.5 to 32.

I think without tweaking the aperture pin spot like I did, all it does is say "I'm using a pentax m lens" to the camera instead of "I'm using an m42 lens" -- you'll note that screw mount lenses in the m42 adapter don't necessarily touch the pins.

There are posts on here that go in depth with the pros and cons.

i think I used this one. Comments not just original post. https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/63878-how-c...s-ka-lens.html
10-24-2014, 08:27 AM   #15
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The bees are shot at just below f/2. Since the aperture jumps from f/1.2 to f/2, I've found that I can still shoot if I leave it somewhere in between. I do this a lot when I want a tad more detail. The train station is shot at f/8, iso: 200, overcast sky with morning mist still in the distance.

The lens also focuses at infinity, but beyond f/8, the focus confirmation goes away. The other thing about shooting "fast lenses", especially in the f/1.2 spectrum, you might want to look into a 3rd party focusing screen. I bought the Katzeye, which helps tremendously. Focusing Screen.com, which I found out about later, sells some great ones that cost less than what I paid for the Katzeye.

I wasn't interested in scraping paint or aluminium tape, so I simply (and I mean, simply) made the aperture modification and haven't looked back. The Porst is totally an "art" lens. Even stopped down, that so called "dreamy feel" remains. Some photographers have little interest in this type of lens, just as some painters favor one brush/canvas over another.

The Pentax-M 50 f/1.7 is the 50 I use most often, simply because it is more predictable and less controversial image wise . But the Porst is a wicked close 2nd, and is always in my bag.

Last edited by strangeboy; 10-24-2014 at 08:34 AM.
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