Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-24-2008, 04:47 AM   #1
New Member




Join Date: Feb 2008
Location: Finland
Photos: Gallery
Posts: 14
K10D long exposure noise issue

I've taken several long exposure shots that show incredibly high noise levels. I took them in PEF RAW file format. Camera showed that exposure was in the middle when I took the photo. It was quite cold (-25 degrees celsius) in the aurora borealis shots. It did this with kit lens. When I swithed to 50mm prime, it was better but it still showed considerable amount of noise.
Second time it did yesterday when I photographed in moonlight. Ambient temperature was around -3 degrees Celsius. Now I have to ask if anyone else has come across this sort of problem. What could be the problem?

Picasa Web Albums - Janne - Aurora Borealis
Picasa Web Albums - Janne - K10D long exp...


Last edited by Smoothster; 02-24-2008 at 04:54 AM. Reason: More noisy photos
02-24-2008, 04:58 AM   #2
Veteran Member




Join Date: Dec 2007
Posts: 923
-25 C is far below the recommended operating temperature of the K10D (0 C to 40 C- page 3 of the manual). You have shown that it does operate at such low temperatures, probably won't produce good pictures, though.
02-24-2008, 05:09 AM   #3
New Member




Join Date: Feb 2008
Location: Finland
Photos: Gallery
Posts: 14
Original Poster
I think the ambient temperature is not the real issue here. It could be related to ambient temperature as temperature changes might get moisture inside the camera or the lenses. I think it might have something to do with raw-files. Shame I did not shoot raw+jpg.
This one was taken at around same ambient temperature, 30s exposure jpg.
Picasa Web Albums - Janne - Sceneries
It shows no visible noise in this shot. Could it have something to do with how the camera processes raw images?

Last edited by Smoothster; 02-24-2008 at 06:27 AM.
02-24-2008, 06:28 AM   #4
Veteran Member
vievetrick's Avatar

Join Date: Sep 2006
Location: Easthampton - Massachusetts - USA
Photos: Gallery
Posts: 5,175
out of curiosity and to ask the obvious question? What ISO did you use? What if any PP work did you do. These look like high ISO or you tried to increase the expsoure after the fact. I will be shocked if you used anything less the ISO800 for these.

02-24-2008, 06:38 AM   #5
New Member




Join Date: Feb 2008
Location: Finland
Photos: Gallery
Posts: 14
Original Poster
I shot these with ISO100. These are basically as "straight out of the camera" RAW's as you can get. They looked similar when viewing them on the camera display. In the noise gallery, I just loaded them to Picasa and transferred them online. They look quite the same in Photolaboratory.

Last edited by Smoothster; 02-24-2008 at 06:47 AM.
02-24-2008, 07:54 AM   #6
Veteran Member
vievetrick's Avatar

Join Date: Sep 2006
Location: Easthampton - Massachusetts - USA
Photos: Gallery
Posts: 5,175
HMM, I have scene and taken my self some long exposures and not had this problem. not sure if it is the camera of the lens.
02-24-2008, 08:44 AM   #7
McD
Senior Member
McD's Avatar

Join Date: Jan 2007
Location: Bracebridge, Ontario
Photos: Gallery | Albums
Posts: 134
Hmmm, that's weird as I have also never really had any high noise issues with long exposures. The other night I shot a photo with about a 10min exposure and had little to no noise. As for the cold weather I can say that's definatly not the issue. I shot a three day snowmobile event when it was -30 to -40 degree's celcius out and had no issues. Didn't even go through any batteries. Gotta love the K10
02-24-2008, 08:47 AM   #8
New Member




Join Date: Feb 2008
Posts: 4
Janne: To me it looks like original pictures have been underexposed and Picasa has cranked up the exposure of pictures. When handling RAW pictures in Picasa, it can adjust exposure rather radically without notifying you.

02-24-2008, 09:45 AM   #9
Veteran Member
vievetrick's Avatar

Join Date: Sep 2006
Location: Easthampton - Massachusetts - USA
Photos: Gallery
Posts: 5,175
that is really what it looks like to me. That is why I asked.
02-24-2008, 09:51 AM   #10
New Member




Join Date: Feb 2008
Posts: 4
To clarify: you cannot call images viewed/saved using Picasa as "straight out of the camera" RAW' because Picasa does heavy post-processing without asking...

You could try to process the RAW images with another program just to be sure. My favourite is Bibble.
02-24-2008, 10:50 AM   #11
New Member




Join Date: Feb 2008
Location: Finland
Photos: Gallery
Posts: 14
Original Poster
So this could be an issue of camera underexposing quite heavily. But when I took the most noisiest shots in the gallery saturday morning, they looked the same in the camera display than in Picasa. Does K10D crank up exposure to view the RAW files as if in camera jpegs are underexposed, they just look black? If it does that, then it would be impossible to check exposure by viewing the file in camera. I've fiddled around with them with Pentax photolaboratory and it defaults to show pictures exactly as you see in Picasa. Doesn't it take default values from the raw file?

Last edited by Smoothster; 02-24-2008 at 11:08 AM.
02-24-2008, 11:17 AM   #12
Veteran Member
TourDeForce's Avatar

Join Date: Jan 2008
Location: Florida
Photos: Gallery
Posts: 512
QuoteOriginally posted by Smoothster Quote
I think the ambient temperature is not the real issue here. It could be related to ambient temperature as temperature changes might get moisture inside the camera or the lenses. I think it might have something to do with raw-files. Shame I did not shoot raw+jpg.
This one was taken at around same ambient temperature, 30s exposure jpg.
Picasa Web Albums - Janne - Sceneries
It shows no visible noise in this shot. Could it have something to do with how the camera processes raw images?
I don't have a K10, so I don't know if this is a common or design problem with them, but just a guess:

... the electronics may be getting some condensation on them at those temps, and that may be affecting the picture quality. Evidence for that is the cleaner .jpg files vs the raw images. Your camera doesn't have to be as cold as ambient either. If it's cold enouth inside to condense moisture, that's it...

Back when shooting in cold temps in Maine with film cameras a few of the newspaper reporter competition would freeze up their equipment or it would become partially inoperative or metering would be fairly far off, but with my old manual K1000 I was able to get good shots in conditions where they wouldn't even bother to break out their fancy cameras (-25F to -40F).
02-24-2008, 11:36 AM   #13
New Member




Join Date: Feb 2008
Posts: 4
Janne, the camera display on K10D has always showed me a "proper" image. I think K10D has a tendency to underexpose, but not that much.

To me your noise samples look just like the ones I get when I crank up exposure at postprocessing. If you're getting this noise already in the camera at low ISO, I have no explanation. Maybe it's some kind of bug.

I presume you've checked all the settings (EV correction, auto ISO etc.) and are using new firmware (1.1 or 1.2 had some fixes related to noise banding).

About the temperature: My understanding is that the high temperature at sensor causes noise - lower temperature is actually good for reducing noise. Not that it really matters in this case. First thing giving you problems at low temperatures is the battery. Moisture becomes a problem when you take the cold camera indoors (that's after the pictures have been taken...).
02-24-2008, 12:05 PM   #14
New Member




Join Date: Feb 2008
Location: Finland
Photos: Gallery
Posts: 14
Original Poster
Thanks for the advise Samikki. Nothing wrong with RAW-files. The noise was produced by Picasa cranking up light. I converted the RAW's using Pentax photolaboratory and full automatic mode.

They looked fine except that most of the shots were severely underexposed. Picasa was cranking up light and produced the huge amount of noise. I seemed to have had the Photolab in manual mode for some reason and that's probably why the pictures turned quite the same as in Picasa.
I turned to automatic and batch processed them all. Photolaboratory produced much better result. Moon now looks like a moon:
Picasa Web Albums - Janne - K10D long exp...

So this comes down to a question: why did camera underexpose? I copied the RAW-files back to the memory card and camera now shows them allright.

Edit: I had the "Bright/Dark- area" highlighting turned on. Because the whole photo is next to black, it blinks the ghost image which looks quite what you get out of Picasa when it cranks up light. Prime did not show this because it underexposed a bit less.

I was using aperture priority mode, used the green button to get time value. When I realized it was underexposing, I cranked exposure compensation up, eventually to +3 stops. Still the shots got somewhat underexposed.
This photo has exposure compensation +3. Picasa Web Albums - Janne - K10D long exp...
Why do they underexpose?

Last edited by Smoothster; 02-24-2008 at 12:51 PM.
02-24-2008, 01:16 PM   #15
Pentaxian




Join Date: Apr 2007
Location: Sweden
Posts: 1,932
It was probably too dark (with that particularly lens) for the cameras metering system. When that happens the camera defaults to a shutter and f-number that is way off and it then flashes the numbers in the viewfinder and on the top-lcd too inform you that you are on your own. If you still shoot with that setting you will get severely underexposed pictures.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
albums, aurora, camera, dslr, exposure, janne, noise, photography, picasa, shots, web
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentax K10D long exposure noise reduction when shooting RAW? Robert S Donovan Pentax DSLR Discussion 30 08-19-2013 11:42 AM
Long exposure camera noise Alex00 Pentax DSLR Discussion 2 02-27-2010 05:55 AM
long exposure noise? slow2focus Troubleshooting and Beginner Help 9 12-16-2009 09:24 PM
Which is worse for noise? Long Exposure or High ISO boodiespost Troubleshooting and Beginner Help 7 12-10-2009 07:57 AM
K-x long exposure noise? er1kksen Pentax DSLR Discussion 4 11-06-2009 01:17 PM



All times are GMT -7. The time now is 11:10 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top