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01-02-2014, 11:04 PM   #1
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Lenses always stopping down to min aperature. Help.

This is really wierd, I just switched lenses for the first time in maybe 2-3 weeks and ran into a really weird issue. My K-30 is always stopping down to the minimum aperture on all of my lenses except for the DA 16-45. The optical viewfinder still looks normal and wide open but when it snaps the picture or if I switch to LV it closes the aperture down all the way.

It takes the picture with the exposure that it should take at the f-stop that is set but it always comes out under exposed unless I set the ap to the max.

Attached there are three pictures of the same seen taken in AV with the maximum aperture set using three different lenses.

DA 16-45 @ 45 mm Av f/4 actually at f/4
Name:  DA16_45-001.JPG
Views: 434
Size:  49.1 KB

DA 21 mm ltd Av f/3.2 actually at f/22
Name:  DA21-001.JPG
Views: 418
Size:  17.4 KB

Sigma 50 mm Av f/1.4 actually at f/16
Name:  Sigma50-001.JPG
Views: 452
Size:  26.7 KB

Has anyone else ever had this happen and if so how do you fix it?

01-03-2014, 07:40 AM   #2
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I had a similar situation on my K200d, it turned out to be some crud on the electrical pins on the camera. You might want to give them a good look at.

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01-03-2014, 08:53 AM   #3
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I looked at that and they looked clean on both the camera and lens, I was thinking about swabbing them with some isopropyl alcohol.
01-03-2014, 10:39 AM   #4
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QuoteOriginally posted by mikemike Quote
I looked at that and they looked clean on both the camera and lens, I was thinking about swabbing them with some isopropyl alcohol.
I can't say what to clean it with, but mine was a physical piece of crud which I just removed.

Tuggie76

01-03-2014, 03:37 PM   #5
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QuoteOriginally posted by mikemike Quote
I looked at that and they looked clean on both the camera and lens, I was thinking about swabbing them with some isopropyl alcohol.
I would avoid alcohol, or any solvent for that matter. It is difficult to know what that will do to the plastic parts, especially the insulation into which the contacts are embedded. The best thing is probably some rough paper, or perhaps something like the cardboard from a cereal box.

In case of very heavy contamination a glass fibre brush could help - not just any fibre glass brush but those made specifically for cleaning electrical contacts. Something like this:
Fibre Fiber Pen Fibreglass Abrasive Circuit Contact Cleaning Pen & 5 Refills | eBay

You wouldn't want to clean too often with it though as it is actually abrasive and will scrape off the gold plating of the contacts if used too often.
01-03-2014, 05:07 PM   #6
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It was clean, but to be extra careful I wiped it with a microfiber lens cloth. I also reset the camera's settings but it is still behaving the same. Any other ideas?

Mount:
Name:  Mount.jpg
Views: 558
Size:  70.9 KB
Which of these ins controls the aperture or is it that lever doo hickie on the left side inside of the mount?

LV Off:
Name:  Lens_NoLV.jpg
Views: 455
Size:  86.2 KB

LV On (supposed to be f/1.4):
Name:  Lens_LV.jpg
Views: 458
Size:  93.5 KB
01-03-2014, 07:08 PM   #7
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QuoteOriginally posted by mikemike Quote
It was clean, but to be extra careful I wiped it with a microfiber lens cloth. I also reset the camera's settings but it is still behaving the same. Any other ideas?

Mount:
Attachment 200749
Which of these ins controls the aperture or is it that lever doo hickie on the left side inside of the mount?

LV Off:
Attachment 200750

LV On (supposed to be f/1.4):
Attachment 200751
Sorry, that's all I got!

Tuggie76
01-04-2014, 06:49 AM   #8
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Because it is an issue on only some lenses I would look at the lens, Check the contacts and the stop-down lever on the lens, sometimes it gets bent on the lens and doesn't align with the lever on the camera body. This will cause it to not stop down correctly.

01-04-2014, 07:07 AM   #9
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The aperture is controlled by that lever you mention. The aperture opens according to how far that lever moves.

The contacts are also involved in the aperture but as far as I know only to the extent of telling the camera what are the minimum and maximum apertures that the lens is capable of. If something goes wrong there you will see unreasonable figures for the aperture setting, such as seeing F1.2 for a lens that only opens to F3.5, or even a '--' sign instead of the aperture.

My guess is there's something wrong with the mechanism that drives that lever. Might even be just some crud in the mechanism.

Something that can also happen is that the lever gets bent out of shape, possibly a mishap when mounting a lens. If you have access to another K-30 try comparing the lever on the two cameras and see if it is exactly the same. I once fixed a similar problem on a Cosina film SLR by simply bending back the lever to its correct shape. (The Cosina had a Pentax-K mount).

Edit: Correction - I've just realised that although also a K-mount, the way the aperture lever is made in the K-30 it cannot bend in the same way as it did on the Cosina I refer to. On looking closer at my K-30 it looks like there isn't any way it can be bent out of shape without being broken so there's nothing to bend back into shape.

Last edited by lister6520; 01-04-2014 at 07:12 AM.
01-05-2014, 02:56 PM   #10
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I was thinking the lever on the lens is bent, not on the camera mount
01-06-2014, 05:10 PM   #11
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I was about to send this to pentax but then I got home and a package that I ordered arrived today and I think I have found the ghost in the machine. I bought a AA adapter to simplify my kit so that the camera and flash all used the same charger, it just arrived today and I put that in and tested it out and all of the lenses are working correctly. I had been using the stock D-LI109 that came with the camera since I bought it a year ago. I charged up the old battery and found that on a full charge, both lenses worked properly for a while. After a few shots LV was malfunctioning and after a few more shots non-LV was exhibiting the same behavior.

The only atypical usage I had done since the last time I used my other lenses successfully was shooting video on Christmas morning. I am guessing that load pushed the battery over an edge. On that day, the camera had ended the video after 20:43 minutes without me stopping recording. I thought at the time it was just some default or something to kill it after 20 minutes but now I think it probably pushed the battery past its limit and did some permanent damage to the battery.
01-06-2014, 05:16 PM   #12
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QuoteOriginally posted by mikemike Quote
I was about to send this to pentax but then I got home and a package that I ordered arrived today and I think I have found the ghost in the machine. I bought a AA adapter to simplify my kit so that the camera and flash all used the same charger, it just arrived today and I put that in and tested it out and all of the lenses are working correctly. I had been using the stock D-LI109 that came with the camera since I bought it a year ago. I charged up the old battery and found that on a full charge, both lenses worked properly for a while. After a few shots LV was malfunctioning and after a few more shots non-LV was exhibiting the same behavior.

The only atypical usage I had done since the last time I used my other lenses successfully was shooting video on Christmas morning. I am guessing that load pushed the battery over an edge. On that day, the camera had ended the video after 20:43 minutes without me stopping recording. I thought at the time it was just some default or something to kill it after 20 minutes but now I think it probably pushed the battery past its limit and did some permanent damage to the battery.
Thats interesting. Good investigative work.
i hope that that is all it is.
I was about to suggest faulty aperture drive motor. but a defective battery is oh so much easier to fix. i hope the new batter fixes it.
01-06-2014, 05:42 PM   #13
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Get a replacement battery if you still need li-ions otherwise use AA all the way
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