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03-12-2011, 01:41 PM   #1
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K20D exposure woes

Hi everyone,

I'll start by saying that I'm pretty new to photography and would like some help diagnosing a problem with my newly acquired K20. Not sure if it user, mechanical, incorrect setting etc.

When I attempt to take photos all I get is a black screen. The histogram only has a small reading on the left side and nothing elsewhere. If I stop down to f13 range I can start to get pictures but they don't look very good.

I purchased this to replace my *ist DS which I was able to operate with no troubles.

Any insight? Is something wrong with this camera?

Thanks in advance for any help.

-Nick

03-12-2011, 02:22 PM   #2
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Nick, there isn't enough information to know why there is such gross underexposure.
For starters, go out in the day time, shoot a few shots at f/8, and see the exposure of the images.
Then, if you want to stop down further, ensure that if you're handholding you have a fast enough shutter speed to get sharp subjects in your images.

If this is a little vague, then a quick read on the exposure triad will give you the info you need to get good shots from the camera.

https://www.pentaxforums.com/forums/photography-articles/62522-exposure-shutt...rture-iso.html
https://www.pentaxforums.com/forums/photography-articles/23232-learning-basic...echniques.html
03-12-2011, 02:33 PM   #3
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Ash is right. There's not enough information here.

What lens are you using? What camera mode are you using? What ISO setting are you using? Where are you taking the pictures, indoors or outdoors? What type of light are you using? Ambient light or flash? If flash, what model flash?

Posting a picture, with EXIF intact, would help.
03-12-2011, 02:43 PM   #4
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I am going to assume that since you replaced your *ist DS with the K20d, you know HOW to take a photo. You said if you stop down to f13 you start to see things happen. Where are you starting? With what lens? Shutter speed? At this point, the others are correct. Pics or it didn't happen (to borrow a blunt phrase).



03-12-2011, 04:47 PM   #5
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Hi Guys,

Thanks for the quick replies and sorry for the lack of information.

I've tried two lenses on the camera, both of which work on my DS. The 18-55 kit lens and an FA 50mm f1.7.

With my 50mm I've used f1.7 indoors on my DS quite frequently. Popping it onto the K20 and I just get a black screen unless I stop down significantly f13+

It behaves the same in all camera modes, outdoors or indoors.

If I put the camera in Tv mode and use a really long shutter speed I can get brighter pictures.

What it seems like to me is that the camera is not properly opening the aperture and is solely relying on shutter speed to capture light.

Is this possible? I could post a pic...but it's just black and not sure if it would be of any help.

Thanks again.

-Nick
03-12-2011, 05:11 PM   #6
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Nick, something's not quite right - and it sounds like the K20D's diaphragm lever. Whether the lens is not allowed to remain at larger apertures during the exposure is hard to elucidate, but if shutter speed's the determinant, then the lens is being fully stopped down regardless of the setting on the camera. Check the aperture lever on both the lens and camera - there should be easy movement of both. Given the lens works fine on the DS then it's less likely to be the lens at fault. The camera's my punt.
03-12-2011, 05:35 PM   #7
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What SHOULD happen is this...

When you put your lens on the camera, regardless of how the camera is set, the lens should be wide open. You should be able to hold the viewfinder up to light and look through the lens to the lit viewfinder. If you've set your FA on A (auto aperture), the camera can command (or should be able to) the aperture in any mode. If you've taken it Off of A and set the aperture manually, the camera will only shoot wide open in any mode but M. Except for the aperture ring bit, your kit lens should work exactly the same way.

If the lens is not held wide open when mounted on the camera, then Ash may be correct, a messed up aperture lever. I've read of the springs on them coming loose on some cameras. If you determine that the aperture is working properly, check to make sure the mirror is flipping up. If that's working, try a B shot to see if the shutter is actually opening all the way. Beyond that, I think we're dealing with an electronic problem. I don't have any Fix it suggestions for you but at least you may discover what is going on.


Last edited by JeffJS; 03-12-2011 at 06:55 PM.
03-12-2011, 06:01 PM   #8
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Hmm,

I just did a test of my own using the 50mm.

Set both cameras to manual mode 1s shutter speed and f1.7 and f22 for both cameras. Then I looked at the front of the lens when I pushed the shutter.

On the DS f1.7 is clearly wide open and f22 is clearly closed while on the k20 the two apertures look exactly the same.

I think my suspicions are confirmed and there is a mechanical/electrical problem with the camera.

Thanks for your help!

-Nick

03-12-2011, 08:11 PM   #9
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I vaguely remember some people having trouble with a spring on the camera's aperture control arm. That's the small black tab on the left of the mirror, between the lens locking pin and the red dot. If the arm doesn't move, the lens never stops down. I think the spring sometimes was falling off and the repair is hooking it back on.
03-22-2011, 03:45 PM   #10
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Awesome. Now my *ist DS is doing the exact same thing.

Worked fine yesterday. I must have some sort of curse.

No lenses work at all. Wedding on Saturday.
03-22-2011, 04:57 PM   #11
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I worry that two cameras I have used have the same problem. Kinda points the finger at user error? What could I have done?

Aperture control is working and possibly I mid-diagnosed the k20 as well.

Not sure what to do.
03-22-2011, 05:25 PM   #12
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First step, go into the menu and Reset All. Then try P and Green mode. if you don't get a decent photo in reasonable conditions, it's probably defective.
03-23-2011, 01:03 AM   #13
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Indeed, in green mode and in sunlit scenes, there should be no way you'll get a black image if your cameras are working properly. Go back to basics and work your way from there.
03-23-2011, 04:51 AM   #14
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My first thought is that the camera is in manual mode... but that sounds too simple...
03-23-2011, 12:00 PM   #15
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There is not enough data for me to even make a guess as what goes wrong.

Please read this thread and see if the problem is the same as yours.
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