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06-20-2013, 02:58 PM   #1
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k-x way under exposes on start up

My K-x that I bought in 2010 got this weird habbit recently of way under exposing on start up.

I turn it on, take a few picutures and they are nearly all dark. (yes, the lens cap is off you jolly joker)

I take a few of a light and the light is visible, but very dark for a picture of a light.

If a take like 10 pics at the 4.7 fps, it SOMETIMES fixes itself without any changes in settings.

Things I've tried and it still happens
1) Different lens
2) many different modes (auto, manual, Av, LV, etc)
3) different iso
4) new batteries
5) different SD card
6) reset to defaults in menu
7) take picture with a flash

It has the AL lenses that came with the kit
Firmware is 1.01
The camera functions normally except for exposure problem.

Thoughts?


Also, is there something on the lens contacts that may make this happen? Maybe I need to clean all the contacts?

06-20-2013, 03:29 PM   #2
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I would start with cleaning the lens contacts. Though the fact that it is happening on multiple lenses sort of rules that out. Still needs done to eliminate it. Also, examine the contacts carefully, they should all be the same height and present in the retainers.

Next check the aperture lever to see if it is moving freely and is not bent in any way. Again I doubt this is the problem but it needs eliminated as a possible issue.

Next look in the camera as you take a picture and watch the aperture blades, what are they doing? Put the camera in manual and set f/3.5 and a slow speed (like 1second), look in and observe. Now set the aperture to f/22 and repeat, what did the blades do this time? For f/22 you should see the lens stop down while the shutter is open then open up again, for f/3.5 probably not much happened. These observations should tell you what is happening with the aperture.
06-24-2013, 10:13 AM   #3
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QuoteOriginally posted by jatrax Quote
I would start with cleaning the lens contacts. Though the fact that it is happening on multiple lenses sort of rules that out. Still needs done to eliminate it. Also, examine the contacts carefully, they should all be the same height and present in the retainers.

Next check the aperture lever to see if it is moving freely and is not bent in any way. Again I doubt this is the problem but it needs eliminated as a possible issue.

Next look in the camera as you take a picture and watch the aperture blades, what are they doing? Put the camera in manual and set f/3.5 and a slow speed (like 1second), look in and observe. Now set the aperture to f/22 and repeat, what did the blades do this time? For f/22 you should see the lens stop down while the shutter is open then open up again, for f/3.5 probably not much happened. These observations should tell you what is happening with the aperture.
Thanks for your help
It appears the aperture blades are stopping down to F22 (or 32, IIRC) not matter what lens I use, or fstop. In manual, or auto, they still stop down.

I checked the lenses and they appear to be smooth moving with little effort to moving the aperture blades manually.

There appears to be a vertical drive screw that controls the interaction with the lens. I have to wonder if it "needs grease". I have a number of precision tool and oilers. What would be the proper grease to use so it won't out gas and get on the lens?
06-24-2013, 11:45 AM   #4
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QuoteOriginally posted by ziscwg Quote
There appears to be a vertical drive screw that controls the interaction with the lens.
Screw drive is for the auto focus. DO NOT OIL THIS. In fact there is nothing on that camera that needs oil or grease.

The aperture is moved by the lever on the side of the mount. It is possible this is bent. Check it for movement with the lens off.

Also, have you checked your exposure compensation? Make sure that is at zero.

06-25-2013, 04:52 PM   #5
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QuoteOriginally posted by jatrax Quote
Screw drive is for the auto focus. DO NOT OIL THIS. In fact there is nothing on that camera that needs oil or grease.

The aperture is moved by the lever on the side of the mount. It is possible this is bent. Check it for movement with the lens off.

Also, have you checked your exposure compensation? Make sure that is at zero.
Thanks for you help on that screw drive. I probably would have done more research to make sure I was doing the right thing. So, it appears there's nothing to "fix"

As for that lever on the side of the mount,
It appears fine and this problem is on 2 lenses. The lenses respond normally too.

What I did test is to what point the aperture starts to work. When I get it to f14, the exposure starts to look like the camera is working better. So, something in the camera is not holding the aperture lever open when it's supposed to be.

I will do a firmware update since I only have 1.01 and 1.03 is avail. It would be cool if an update fixed the problem, but I'm not holding my breath
06-25-2013, 06:23 PM   #6
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QuoteOriginally posted by ziscwg Quote
I will do a firmware update since I only have 1.01 and 1.03 is avail. It would be cool if an update fixed the problem, but I'm not holding my breath
Seriously doubt that will help, but it cannot hurt.

Is the error consistent or random? If it is consistent I would think maybe something is set wrong. If it changes randomly then I'm still leaning toward something wrong with the aperture lever. You might have to send it in for service.
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