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12-04-2017, 07:19 PM   #1
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K1 Legacy lens compatabilty issues or broken??

So I just received my Porst 55mm F:1.2 in the mail and am troubled to find that the aperture doesn't function properly on my K1 OR my K-70.
I just sent back another lens that had this very same issue. (both bought from Europe coincidentally)

On my K1 the aperture fails to stop down during the shutter release, and remains fully open no matter what I set it to.
On my k-70 the aperture stays fixed to whatever setting it is at, regardless of the shutter, so if I set it to f22 its too dark to even see through the viewfinder.

What is the issue here? Are there legacy issues with modern DSLR's for some k-mount lenses? Does Europe sell junk used lenses? Is Santa even real?

12-04-2017, 07:33 PM   #2
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The lens functions just fine. It is a manual lens. You have to manually adjust the aperture and use the green button to determine what kind of exposure you want.

Also you have to have the settings on the camera body set to accept manual lenses.

If you have done those two things first, then let us know.
12-04-2017, 07:41 PM   #3
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Hit the menu button on the bottom right of the back of your camera>>> scroll over to "C" menu>>>>Go to #26 "Using Aperture Ring" and set it to 'enable' (this is for the K-1)

After you do that set your aperture to whatever you want it to be for a particular test shot. Say f5.6 for example---then press the green button near the top right corner of your display on the back of your camera. It will depend on which mode you are using on your camera (I only use 'manual settings') so in that mode it will adjust your shutter speed according to your lighting and ISO.

There are whole big threads on how to use the green button.
12-04-2017, 07:56 PM   #4
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LIke Alamo 5000 said for some reason Pentax requires you to go into the menu and select allow aperture ring use. Not sure why it is stopped down on the K-70. On my bodies the M and K series lenses stay open till the green button stops it down for meter. Also you need to be in M mode I believe for the camera lens setup to work properly.



Edit I type to slow. Alamo5000 added this inf

12-04-2017, 07:57 PM   #5
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additionally, the Porst Color Reflex MC Auto 55mm f1.2 has an anodized mount, so the body will not communicate with the lens at all, unless you short the data pin...

I used copper conductive tape to short mine and it works awesomely...
12-04-2017, 07:57 PM   #6
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This might be useful reading: How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com
12-04-2017, 07:59 PM   #7
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you have to enable using aperture ring , do not have K-1 with me but on K-3 it is in Menu C page 4 item 27.
you need to use M mode , choose the aperture with the ring, press green button to get the right shutter speed
12-04-2017, 09:19 PM   #8
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No to all counts of the suggestions so far.
Has nothing to do with the regular legacy settings or the green button. I've got plenty of Manual Pentax glass that works perfectly.

This lens will not stop down once mounted on the K-1.

---------- Post added 12-04-17 at 10:22 PM ----------

QuoteOriginally posted by pepperberry farm Quote
additionally, the Porst Color Reflex MC Auto 55mm f1.2 has an anodized mount, so the body will not communicate with the lens at all, unless you short the data pin...

I used copper conductive tape to short mine and it works awesomely...
I'm not sure what you're referring to here.... none of the fully manual glass communicates with the body.??

Do I need to add contacts due to the anodized mount to make the camera realize a lens is mounted?

---------- Post added 12-04-17 at 10:36 PM ----------

OK, this is weird....I just stuck it back on and used in live view, and it started functioning properly and actuating the aperture properly....


Last edited by Leumas; 12-04-2017 at 09:28 PM.
12-04-2017, 10:52 PM - 2 Likes   #9
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QuoteOriginally posted by Leumas Quote
No to all counts of the suggestions so far.
Has nothing to do with the regular legacy settings or the green button. I've got plenty of Manual Pentax glass that works perfectly.

This lens will not stop down once mounted on the K-1.

---------- Post added 12-04-17 at 10:22 PM ----------



I'm not sure what you're referring to here.... none of the fully manual glass communicates with the body.??

Do I need to add contacts due to the anodized mount to make the camera realize a lens is mounted?

---------- Post added 12-04-17 at 10:36 PM ----------

OK, this is weird....I just stuck it back on and used in live view, and it started functioning properly and actuating the aperture properly....
Read this: Manual lens that won't change aperture on camera - PentaxForums.com
12-04-2017, 11:56 PM   #10
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Think we narrowed it down, I had no idea about the lens base needing to be conductive.

Thanks for all the input guys
12-05-2017, 12:14 AM   #11
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QuoteOriginally posted by Leumas Quote
Think we narrowed it down, I had no idea about the lens base needing to be conductive.

Thanks for all the input guys
This is the place to be. There are a lot of people way smarter and have a whole lot more information than I do around here
12-05-2017, 01:06 AM - 2 Likes   #12
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QuoteOriginally posted by Leumas Quote


I'm not sure what you're referring to here.... none of the fully manual glass communicates with the body.??

Do I need to add contacts due to the anodized mount to make the camera realize a lens is mounted?
yes - this how I modified mine:


Last edited by pepperberry farm; 12-05-2017 at 03:59 AM.
12-05-2017, 06:56 AM - 1 Like   #13
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QuoteOriginally posted by pepperberry farm Quote
yes - this how I modified mine:
Yep, that's the ticket. Easy to do, and very cheap. As seen in the picture, you put it where the "A" contacts would be if it had them.

One strip of tape lasts a while, though eventually friction of mounting and demounting can abrade it and you need to apply more. It's far better than the alternative, which is to file off the anodized coating. That can lead to a lack of corrosion protection for the lens IIRC, and it also harms the resale value, especially for any buyer who doesn't understand why it was done. Save that trick for $5 pawnshop lenses, or haze/fungus-ridden teleconverters you're deglassing to use as extension tubes. Filing down the back of an f/1.2 lens that isn't already thoroughly destroyed should be a capital crime.
12-05-2017, 07:06 AM   #14
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QuoteOriginally posted by pathdoc Quote
Yep, that's the ticket. Easy to do, and very cheap. As seen in the picture, you put it where the "A" contacts would be if it had them.

One strip of tape lasts a while, though eventually friction of mounting and demounting can abrade it and you need to apply more. It's far better than the alternative, which is to file off the anodized coating. That can lead to a lack of corrosion protection for the lens IIRC, and it also harms the resale value, especially for any buyer who doesn't understand why it was done. Save that trick for $5 pawnshop lenses, or haze/fungus-ridden teleconverters you're deglassing to use as extension tubes. Filing down the back of an f/1.2 lens that isn't already thoroughly destroyed should be a capital crime.

agreed - which is why I did not permanently alter the mount...

when I purchased the conductive tape, I had to buy enough to last me several lifetimes of photography... if anyone needs some, PM me and I'll mail you a strip of it for free...
12-05-2017, 07:41 AM   #15
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The "flagship" models will also stop-down meter in manual using the DOF preview if the preview is set to optical. This activates the EV bar meter and you can adjust the exposure by turning the aperture ring or shutter speed with the eDial. Changes in exposure are reflected in EV bar meter. You may have to disable the electronic level. The K-1 is considered a flagship model.

Metal foil tape can be found at just about any auto parts store and most warehouse hardware stores. For a quick check you can always take a piece of aluminum foil and carefully hold it in place while mounting the lens. Take care none of it tears and falls into the mirror box.
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