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08-09-2013, 11:40 AM   #1
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k5 and sigma 17-70

hi all
i have a k5 and a sigma 17-70 non hsm and when i switch the camera on it now asks to input focal lenght
i have cleaned the contacts, but if i slighty turn the lens i seems to be ok

08-09-2013, 12:20 PM   #2
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Sounds like there might be some sort of misalignment. Is there significant wear on the mount?

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08-09-2013, 01:51 PM   #3
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Try to loosen the lens mount a little and tighten it again, worked on my Sigma macro.
08-09-2013, 06:22 PM   #4

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Hi Neil,

When looking at the contacts, I'd say that you should probably pay special attention to the "data" contact, which is closest to the screw on both the body and lens mount. This is the pin through which the camera receives information from the lens chip, ie, lens ID, FL, AF type, and MTF (if supplied). If this contact is either missing or shorted (to the lens mount or camera body), then the camera assumes that the lens is a pre AF series lens, so needs the FL input for SR. If cleaning and Vis Dark's solutions don't work, see if the pin is not at the same height as the others on the lens. If so, the pin could be jammed or the spring might be crimped or collapsed.


10-02-2013, 06:26 AM   #5
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Did you resolve them problem? I'm having the same problem, it works fine on the k10d but not on the k-5.
10-05-2013, 11:50 AM   #6
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QuoteOriginally posted by D1N0 Quote
Did you resolve them problem? I'm having the same problem, it works fine on the k10d but not on the k-5.

no it still does
10-05-2013, 03:17 PM   #7
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10-16-2013, 09:46 PM   #8
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I had the same problem. My lens also developed slop in the zoom and when I went to 70mm I could turn it a bit more and it went from f/4.5 to f/4. I have the old version so it should read f/4.5. And it does if I back off the zoom a bit. When I turned on the camera it would ask for the focal length and or report it wrong in the EXIF data.

I cleaned all contacts camera, lens.

Here was the solution for me. I had to take out the 3 screws that hold the metal mounting plate out and pull up and out the lens mount. There are no wires hooked to it. Only the aperture rod that easily goes back in the lens; and stays hooked to the plate. Remember to pull out the lens focus gear. It just pulls out! Take off the metal spacer and any other spacers. Now you will see the contact assemble with a cable hooked to it. You can lift out the contact data pin assembly; but don't remove the flex cable! Just leave it as is. Don't try and take the flex cable off unless you really know what your doing. Look at the bottom of the contact assemble. There are two very small screws holding the unit together. If you completely remove the screws and let the springs and contacts come out you take a chance of losing very small parts.

What I did was losen the two screws on the data pin contact assemble enough that I could dap a small bit of contact cleaner in it. Really I used WD40 and a q-tip to just let a drop of oil down into the assembly. Now I stuck a very thin pin or what-ever you can find into the opening on the side and moved the contact springs around to help clean its contact with the PCB. Its just pins, springs and a contact to a very small PCB. Over time it can lose this contact on the insides! And its needs a deep cleaning. Also push down the pins repeatedly to help work out the debris, contamination, corrosion.

My Sigma 17-70mm f/2.8-4.5 works great now. Well I did cause some damage, I put a scratch on the outside barrel. That is the risk you take with DIY repair. I suspect a lot of people are starting to run into this problem. As I am reading of it more and more. Lots of people bought this lens five or more years ago.

The logical solution is to clean the contacts. Problem is there is also a contact down under the part you see and can't clean.

It is a very easy job as there are no wires to remove or anything complicated to do. Just need a small screwdriver and remember to remove the focus gear when you get to it, if your lens has it. Which brings up another warning. This is for the older Sigma 17-70mm f/2.8-4.5. I can't say the new f/2.8-4 model is the same.

Now the barrel slop. I fixed that by pulling down the rubber zoom grip and tightened a very lose cam roller screw behind tape and a piece of copper foil, I got lucky on that one. But that's when I left a mark on my lens barrel. Oh well if that's the biggest problem I have to worry about...

Good luck anyone. Ask questions if you want. I should have taken pics. But your so concentrated on the job you don't want to distract yourself.

So to recap. Take out the 3 mounting screws. Be careful there are other small screws on the mounting plate. Just pull off the plate. Remove the focus gear, remove spacers. The contact assemble is free to move. Pull it up and loosen the small screws enough so you can work, but not enough that the parts can come out. Carefully clean the in side moving the springs around and putting a tiny drop of plastic safe solvent on it. Push the pins in and out. Put it back together and you should be good to go.

What I don't get is why my K20 I still have, did not have a contact problem with this lens. Only the K5. I do note in the EXIF Pentax is not supporting the Sigma as much. The K20D list the exact lens. The K5 lists it as one of five different lens!

BTW Please don't do this if not absolutely necessary to use the lens and the lens has little value to you. Do at your own risk!

Last edited by jamesm007; 10-18-2013 at 06:19 AM. Reason: btw, grammer, clairity
10-25-2013, 09:28 AM   #9
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Thx Maybe I'll try that (but I will probably wreck it).

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