| Author | Thread |
|
|
07/30/2007 07:04:37 AM · #1 |
Hey guys, I just bought a new camera, LOVIN it. and I took it out doing some night photography. well I was happy with the results, except... and heres the killer, In the pictures with longer exposures (even only 20 secs or more) there was what looked like dead pixels, in the picture!, first I thought it was on my laptop, but it turns out its on the pictures. what do I do???? bring the camera back? can it be fixed?
|
|
|
|
07/30/2007 07:08:08 AM · #2 |
they aren't dead pixels. they are more than likely casued by the sensor getting hot from the long exposures. pretty common.
|
|
|
|
07/30/2007 07:10:31 AM · #3 |
Is there anything that can be done to prevent it? because If I have really long exposures like an hour they would ruin the whole picture!! they get worse the longer the exposure. they are always in the same spot too! there is always two one red one blue!
|
|
|
|
07/30/2007 07:21:34 AM · #4 |
Take a normal shot with the lens cap on. If you see these pixels in a normal shot, then they are stuck/dead pixels. However, what you are more likely seeing are hot pixels. These are quite common, and you'll see them show up during long exposures. They are caused by some pixels being a bit more 'active' than others - they're fine at short exposures, but show as hot pixels in long exposures.
Two ways around this; 1) Turn on NR mode in your camera, if it has it. This will take a dark frame and subtract it from your main shot, eliminating the dead pixels. or 2) use the dark frame technique to get rid of the hot pixels in post processing (using layers)
However, if only 1/5-millionth of your shot is being affected by these pixels, then I'd say just a quick dab of the clone brush in pp. |
|
|
|
07/30/2007 07:46:51 AM · #5 |
Oh, I almost forgot...
 |
|
|
|
07/30/2007 08:07:23 AM · #6 |
As far as dead pixels go... its a shame other camera manufacturers haven't developed a process for in-camera pixel mapping.
|
|
|
|
07/30/2007 08:31:28 AM · #7 |
Originally posted by jhonan:
Oh, I almost forgot...
|
HILARIOUS!! hahaha
|
|
|
|
07/30/2007 05:38:17 PM · #8 |
***HELP***
ok So i just did a bit of a test on a 2 min exposure, lens cap on their are 10 very noticable bright spots, and on a 5 min exposure, the picture was covered with them. is this normal???? so with my camera am i stuck without being able to take solid Night pictures? or astrophotography?? should I return the camera and get them to send another?
|
|
|
|
07/30/2007 05:47:03 PM · #9 |
| Yes it's pretty normal, digitals camera's werent really designed for such long exposures. 5 minutes is pretty long, there should be tonnes of noise as well as burnt out pixels. |
|
|
|
07/30/2007 06:26:07 PM · #10 |
take a short shot with the lens cap on ( 1/60th ). you'll still get hot pixels with a long exposure whether anything is actually exposed or not.
|
|
|
|
07/30/2007 06:44:07 PM · #11 |
Try turning on Noise Reduction;
//www.robgalbraith.com/bins/multi_page.asp?cid=7-7897-8492
The Rebel XTi/400D's Noise Reduction menu has three options: Off, On and Auto. When set to On, long exposure noise reduction will be applied whenenever the exposure is 1 second or longer. When set to Auto, the camera will analyse the level of noise in exposures between 1 and 30 seconds and apply long exposure noise reduction only if it deems it would be beneficial to the picture. The Rebel XTi/400D locks up the camera for an amount of time equal to the exposure time while it applies long exposure noise reduction. |
|
Home -
Challenges -
Community -
League -
Photos -
Cameras -
Lenses -
Learn -
Help -
Terms of Use -
Privacy -
Top ^
DPChallenge, and website content and design, Copyright © 2001-2025 Challenging Technologies, LLC.
All digital photo copyrights belong to the photographers and may not be used without permission.
Current Server Time: 08/29/2025 11:19:49 AM EDT.
