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09-22-2009, 02:11 AM   #1
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new to K20D and this forum

Hi everyone, i have had a K20D for a few weeks and am having a processing problem I am hoping someone can help me with. I am also very new to the Forum and I have tried to find the answer in here so apologies if this has been covered before ........

Basically what happens is when shooting in M mode and I expose, say a 5 minute time exposure, I have to wait the time of the exposure (in this case 5 minutes) before I can expose the next frame. My son's lower model Pentax has a Menu setting to change this but it seems the K20D does not. I have tried to research this apparent problem on the Net and in the hard copy Manual but I can't find a solution.

I really can't imagine no-one else finds this a problem so if this camera is faulty or the firmware or software are faulty I would love to know before I go to the trouble of sending it back.

Any help would be greatly appreciated

Ian

09-22-2009, 03:01 AM   #2
Ash
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Dark frame subtraction method of noise reduction is not user-removable - it will occur for all long exposures taken with the K20D unfortunately (or fortunately, as the case may be - images may not be as useable otherwise...)

It is not a fault or a glitch in the camera - it is designed to take a separate dark frame of the same duration as the original exposure in order to subtract the inherent noise from the image taken (this is dark frame subtraction).
09-22-2009, 08:18 AM   #3
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As Ash said, dark frame subtraction cannot be completely turned off on any of the Pentax DSLR cameras using the Samsung CMOS. I suspect they disallowed this to hide how very bad the sensor is at long exposure times. If you want to do long time exposures, get one of the cameras that uses the Sony 10mp CCD sensor such as the K10.
I am hoping that the Kx and it's Sony CMOS indicates that Pentax is getting away from using the Samsung sensors.
09-22-2009, 02:20 PM   #4
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I would add to learn to appreciate the 'limitation' as it is doing the work of many expensive noise reducing programs in-camera.

09-23-2009, 07:57 AM   #5
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I too take long duration evening/night images and the "additional" wait is just a fact of life with Pentax (K20). Nothing you can really do about it, short of going to another camera manufacturer, however each one comes with their own particular set of problems (features). Photography is a exercise in compromise.

09-24-2009, 03:03 AM   #6
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thank you all for your replies ..... seems like I had better get used to this camera's idiocynchrocies or else get another camera. Happy with all other aspects and features of the K20D so far.
09-24-2009, 05:21 AM   #7
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Remember if you settle for another camera without this delay, then you're settling for no good long-exposure noise reduction.
09-24-2009, 05:53 AM   #8
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I use the K10 for timed photo's of lightning strikes and it does the shortest dark frame of any Pentax camera that I have tried. 15/30 second delays are not so bad but 5 minutes are tiring time killers. jim

09-24-2009, 11:33 AM   #9
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QuoteOriginally posted by utopiaimagesonline Quote
thank you all for your replies ..... seems like I had better get used to this camera's idiocynchrocies or else get another camera. Happy with all other aspects and features of the K20D so far.
Just to be clear - virtually all cameras offer dark frame subtraction as an option, and msot probably have that enabled by default; it's just that the K20D doesn't let you turn the option off. On the cameras that do let you turn it off, the results usually aren't pretty, an after trying one shot with it off, you end up turning it back on.
09-24-2009, 12:43 PM   #10
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Not a deal breaker but inconvenient

I had this discussion with a Pentax rep recently and expressed my dismay. The points that I brought up as having experimented with long exposures for star trails were as follows:

1. It is unlikely that someone who is taking long bulb exposures is completely oblivious to what they are doing.

2. There is an expectation of noise for these longer exposures.

While I understand that Pentax may not want to reveal how noisy the image can get, I would have expected that they at least give someone the option to turn it off.

Since DFS is simply a frame taken of equal exposure time to reveal irregularities in the amplification of the sensor, I would assume one could easily do this process using the EXIF data and then applying a subtraction in Photoshop (or am I grossly mistaken in this?)

The fact that it doubles the exposure time is certainly less conducive to experimenting with longer night exposures. just taken for instance an exercise in shoot 3 frames: 5min, 10min and 15 min. This would force someone to be out 1hr as opposed to 30 min, nevermind if the lighting conditions for that shot were to change between wait times.
09-24-2009, 01:06 PM   #11
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I really hope that the K-x doesn't have this - almost wish I didn't sell my K2000 now! I forgot that was one of the reasons I went with the K2000 over the K20D, since my tripod has not arrived yet.
09-24-2009, 01:14 PM   #12
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The k200 has the option to turn it off and I disagree that you cant get a good shot without it...



Exposure: 7.6 min
Aperture: f/8.0
Focal Length: 18 mm
Exposure: +0.58
ISO: 400
09-24-2009, 01:21 PM   #13
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did you do any manual DFS? I made a post a while ago about how to do it manually afterwards but didnt get anything!
09-24-2009, 01:45 PM   #14
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I didn't but here is a tip:

DFS Photoshop
09-24-2009, 09:42 PM   #15
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Brilliant image mtroute.
A beautiful scene to behold.
Well done with it.
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