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05-30-2010, 02:18 PM   #1
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New Pentax KX, problem with double shutter movement leading to underexposure

Hi all

I'm a newcomer to DSLRs and purchased my first, a Pentax KX, last week. I'm very happy with it but I'm having an intermittent problem. Occasionally when taking a picture the shutter opens and closes not once, but twice. This appears to happen at random and, when it does happen, seems to happen a few times in a row. It happens regardless of what mode I'm in (it happens in Full Auto as well as full Manual). The resulting shots are drastically underexposed (nearly completely black in most cases) which I think may mean that the shutter is opening twice in the time it should be opening once.

I've tried resetting (although not a full factory reset, as the manual doesn't seem to give any information about that) and playing around with different exposure and focus settings, but so far it seems to me to be happening at random. I haven't got exposure bracketing or anything like that turned on.

I'm worried that this might be either a hardware or firmware problem and so I'm debating whether or not I need to return the camera to Amazon and ask for a replacement. However, as I said, I'm very new to this so I'm open to the possibility that I'm just doing something stupid myself.

I'd be very grateful for any ideas or suggestions you have.

Cheers

05-30-2010, 02:47 PM   #2
hcc
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This is not normal:

- Check that you have the latest firmware.

- If this does not resolve anything, send back the camera for service.

05-30-2010, 02:58 PM   #3
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You may just be hearing the mirror flipping up and down, rather than a double-shutter action. Also are you using LiveView?

It would also help if you posted one of those under-exposed images, with EXIF data intact.
05-30-2010, 02:59 PM   #4
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Oh dear, I was worried that might be the answer! I did update the firmware when the problem first came up, but that didn't do anything.

Thanks for the quick reply HCC.

05-30-2010, 03:21 PM   #5
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Hi Rawr, thanks for your help. I'm not using LiveView, but can't be certain if it's the mirror I'm hearing. I have some RAW images with this problem (I'm assuming that these would contain EXIF data?) but they're pretty big and seem to exceed the upload limit for the forum. I'll try and find somewhere else to post them and link into here if I can.
05-30-2010, 06:40 PM   #6
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The JPG images produced by the camera also contain EXIF information.

If you use a good image viewer (IrfanView, FastStone, etc), they can also shrink and resize JPG images without destroying the EXIF.
05-31-2010, 01:44 AM   #7
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Check if the camera isn't in continuous shooting mode. (pag. 138 in User Manual)
05-31-2010, 03:43 AM   #8
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No, the camera has been in single shot mode the whole time.

I've set up a google site with a copy of a jpg file and a raw file with the problem. I've taken them straight from the card so I hope the EXIF information has been preserved. I shot them both in Auto Pict and with autofocus in the hopes that this would exclude the possibility of me doing something wrong!

They're available here: https://sites.google.com/site/tricerator38/

Thanks for your help everyone.

05-31-2010, 10:12 AM   #9
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I decided to get a little scientific about this, so I tried doing some extended tests with different settings. In general, the problem seems to be happening between 2/100 and 4/100 shots, pretty much regardless of whether the camera is set to single shot or continuous shot and also regardless of whether it's handheld or on a tripod. So let's call that a 3% error rate. (My impression is that it's actually been a slightly higher rate than that because it often repeats several times in a row, so that may be an under-estimate).

However, the problem didn't occur at all when I shot 100 shots in Live View. And, intriguingly, the sound made by Live View (which I actually hadn't used before) is the same as the 'double shutter' sound I'm hearing when the problem occurs. So perhaps that means that it isn't the shutter operating twice but rather some sort of timing issue?

If there is a 3% error rate (or slightly higher), is that normal or should I be looking to get this unit replaced?
05-31-2010, 10:26 AM   #10
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Looking at the EXIF, which, at a first glance, dont't look unusual, it seems to be a hardware or firmware issue. Possible, but very unlikely: the aperture is always stopping down full, which could be body related or (again very unlikely, nearly impossible) lens related. The only time I got similiar problems was when an external flash unit was expected to fire, but for some reason didn't.
05-31-2010, 12:35 PM   #11
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Thanks for the comments and help everyone. I'm reassured that this obviously isn't a problem faced by everyone with the KX, or just a settings issue, but it does seem from what you've said that there is something wrong with my camera. I think I am going to have to try returning it and asking for a replacement.
05-31-2010, 04:02 PM   #12
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All the best in getting the camera fixed.
It seems a weird issue indeed.
05-31-2010, 04:31 PM   #13
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It seems like there is something wrong with your camera. For one thing, a double shutter opening should result in a massively overexposed shot not like the massively underexposed shots you posted. And as RKKS08 has said there doesn't seem to be anything wrong with your EXIF data. I'd ask for a replacement.

NaCl(but it has to be the weirdest problem I've seen)H2O
05-31-2010, 06:19 PM   #14
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I've had the same problem

For a short period of time, my K-x also had the "double shutter" problem. It was occurring as often as you indicated. However, the problem seems to be happening with much less frequency now, even rarely. I have no insight as to why it happens, or why the problem seems to be going away. Strange.
05-31-2010, 07:35 PM   #15
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could it be a battery issue?
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