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12-17-2018, 07:32 AM   #1
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Pentax K1 aperture problem with manual lens

Hi everyone,

My name is Rafa and I'm new on this forum.

I have seen issues that are similar to this one, but haven't found one that is exactly the same, so I hope someone can help me out with this one, here goes:

I bought a Pentax K1 last year, as I already owned a Pentax MX and loved the manual lenses that I had for it.
I recently got my hands on an Autoberoflex 24mm 2.8, as I saw it for a good price on ebay. The lens is in good condition, and seems to work just fine with the MX.

However, the problem comes when I put it on the K1, as, contrary to the other manual lenses I own, it doesn't seem to respond to any changes in the aperture ring (not even when on manual and when pressing the green botton to get the correct exposure). The aperture stays wide open, and whenever i turn the ring and press the green botton, it always gives me the same readings back.

Does anyone have this same issue?

Thanks in advance

12-17-2018, 07:34 AM   #2
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Hello Rafa and welcome.
You didn't say whether thats a K-mount or M42. Is it's mount a black anodised one (= no electrical contact)? if so that's why.

with M42 use Av anyway ie stop down aperture priority. Manually close the iris when you take the pic - there is no aperture lever connection holding the iris pen on M42 (but see other threads and this web page for working with the m42 variants).

Last edited by marcusBMG; 12-17-2018 at 07:43 AM.
12-17-2018, 10:18 AM   #3
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Welcome to the Pentax forums!

Assuming the mount is Pentax-K and that you have aperture ring enabled in the custom menus, the most likely cause is a lens with a non-conductive (painted or anodized) mount face. The body will not trigger the aperture actuator coupling unless it senses that a lens is mounted. The usual remedy is to abrade a portion of the lens flange face* to expose conductive metal or short out one of the body mount contacts with a small piece of foil or conductive tape.


Steve

* I sanded off a patch opposite the "data" pin (about 6 o'clock position) on an anodized close-up ring that I use and the fix works quite well.
12-17-2018, 12:00 PM   #4
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You have already received some good suggestions so I will just welcome you the forum. Keep asking until your problem is solved.

12-18-2018, 01:55 AM   #5
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QuoteOriginally posted by marcusBMG Quote
Hello Rafa and welcome.
You didn't say whether thats a K-mount or M42. Is it's mount a black anodised one (= no electrical contact)? if so that's why.

with M42 use Av anyway ie stop down aperture priority. Manually close the iris when you take the pic - there is no aperture lever connection holding the iris pen on M42 (but see other threads and this web page for working with the m42 variants).
I'm not sure weather it's a K or M42 mount, it fits the camera with no adapter. It is, however, painted black, so I guess that this is where the problem comes from. I have tried Av mode but it doesn't seem to respond either . Thanks a lot for the rest of the info!

---------- Post added 12-18-18 at 02:00 AM ----------

QuoteOriginally posted by stevebrot Quote
Welcome to the Pentax forums!

Assuming the mount is Pentax-K and that you have aperture ring enabled in the custom menus, the most likely cause is a lens with a non-conductive (painted or anodized) mount face. The body will not trigger the aperture actuator coupling unless it senses that a lens is mounted. The usual remedy is to abrade a portion of the lens flange face* to expose conductive metal or short out one of the body mount contacts with a small piece of foil or conductive tape.


Steve

* I sanded off a patch opposite the "data" pin (about 6 o'clock position) on an anodized close-up ring that I use and the fix works quite well.
Everything is in place so that it works with my other manual lenses, as I basically only own manual ones (apart from an old but pretty decent SMC Pentax 35-70, 3.5, which I love). Sanding it off might be the solution, would it be possible to see a picture of where exactly I should sand on the lens, or where I should apply tinfoil? Thanks a lot for the reply!
12-18-2018, 02:49 AM   #6
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QuoteOriginally posted by Rafael Vilallonga Quote
Sanding it off might be the solution, would it be possible to see a picture of where exactly I should sand on the lens, or where I should apply tinfoil? Thanks a lot for the reply!
Remove the paint at the bottom of the lens flange in the area marked "digital-info contact".


From: The K-Mount Page | Features and Operations, KAF Mount



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12-18-2018, 03:03 AM   #7
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A quick and non-destructive way to test this is to place a small piece of metal foil (e.g. kitchen aluminum foil) over the contact before mounting the lens. As long as you are not careless and let the foil drop into the mirror box there should be no problem.

You'd be surprised but now and then we come across people who refuse to believe the coating on the mount can be the problem and refuse to even try such a simple test which would shatter their beliefs.
12-18-2018, 03:52 PM   #8
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Late to the party... I'm sure if you follow the good advice already given her to you here, your issues will be resolved, so I'll just say welcome to the forum.

12-19-2018, 01:30 AM   #9
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QuoteOriginally posted by stevebrot Quote
Remove the paint at the bottom of the lens flange in the area marked "digital-info contact".


From: The K-Mount Page | Features and Operations, KAF Mount



Steve
Wow, thanks a lot for this!
12-19-2018, 01:31 AM   #10
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QuoteOriginally posted by Not a Number Quote
A quick and non-destructive way to test this is to place a small piece of metal foil (e.g. kitchen aluminum foil) over the contact before mounting the lens. As long as you are not careless and let the foil drop into the mirror box there should be no problem.

You'd be surprised but now and then we come across people who refuse to believe the coating on the mount can be the problem and refuse to even try such a simple test which would shatter their beliefs.
I guess it can be quite scary for some people. I'll give this a try aswell though, thanks a lot!
12-20-2018, 04:48 AM - 1 Like   #11
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QuoteOriginally posted by stevebrot Quote
Remove the paint at the bottom of the lens flange in the area marked "digital-info contact".


From: The K-Mount Page | Features and Operations, KAF Mount



Steve
I filed the paint in that exact point and it works now! Thanks again for the tip, really helpful (and made me feel like McGyver for a second there). Thanks again!
12-23-2018, 02:12 PM   #12
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Welcome to the forum!
Glad to hear you have the issue sorted.
Kind regards,
Mark
(New Zealand)
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