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Digital Cameras

I'm shocked with this picture.. help me

mattar_3d
 
Posts: 13

I'm shocked with this picture.. help me

Post Tue May 20, 2008 9:48 pm


Please help me...
I took this picture on a shutter speed 60sec ... ( Blub)... by the Nikon D300 ... with ISO:100
What are these dots that are showing in this picture? ? is it just dust ?? or another thing??
So is the sensor damaged? or its just dust?
http://img375.imageshack.us/my.php?image=dsc69561jw9.jpg

prinothcat
 
Posts: 662

Re: I'm shocked with this picture.. help me

Post Tue May 20, 2008 11:00 pm


I vote for dust... If you had shot a longer exposure I would change my vote to noise generated by the long exposure time.

dougj
 
Posts: 2276

Re: I'm shocked with this picture.. help me

Post Wed May 21, 2008 12:24 am


With a shutter speed of 60 seconds they look like hot pixels IMHO, not too surprising for a long exposure. Check your camera manual and see if you have an option for dark frame subtraction or noise reduction using second frame subtraction - not another noise reduction mode. Most DSLRs have this to eliminate what you see. Basically a second frame is exposed with the same ISO & shutter speed but the shutter stays closed, this is then subtracted from the photo. This can do a good job correcting some types of detractions, the downside is it takes the same time for the dark frame as it does for the photo, so it takes longer, and it will only correct for hot pixels, etc. that are consistent & repeatable from shot to shot.

dang
 
Posts: 3780

Re: I'm shocked with this picture.. help me

Post Wed May 21, 2008 6:11 am


Oh jeez, I hate those blasted pop-up ads the shack has, but anyway...

I agree 100% with Doug. Dust shows as dark spots, usually on lighter areas, and not colored pixels. I'd imagine prinothcat was thinking 1/60th. :wink:

prinothcat
 
Posts: 662

Re: I'm shocked with this picture.. help me

Post Thu May 22, 2008 1:26 am


prinothcat wrote:I vote for dust... If you had shot a longer exposure I would change my vote to noise generated by the long exposure time.


OOH I'm in need of reading lessons it appears... I miss read 60 sec for 1/60... duh....
So can I change my vote to noise? The hot pixel idea has merit as well.

dougj
 
Posts: 2276

Re: I'm shocked with this picture.. help me

Post Thu May 22, 2008 2:54 am


LOL - The only reason I might have gotten it right is because I was wearing my reading glasses....and read it a few times. My replies can be rather comical when I don't wear my glasses. Your new vote has been duly recorded Chris :mrgreen:

cmit
 
Posts: 16

Re: I'm shocked with this picture.. help me

Post Thu May 22, 2008 8:25 am


If they are hot pixels then you should return your camera under warranty - 60 secs is not long.

If you want to check it:

Leave the lens cap on, Switch to Manual, expose for 60 secs. You will end up with a black exposure and the hot pixels will stand out. If there are just one or two, this is common, but if there are lots, you should definitely get it checked.

dougj
 
Posts: 2276

Re: I'm shocked with this picture.. help me

Post Thu May 22, 2008 7:15 pm


It's common for hot pixels to appear with shutter speeds below 60 seconds, it's a question of how many and if the manufacturer will exchange the camera or remap the defective pixels. You can try the test cmit described and visualize the results.

prinothcat
 
Posts: 662

Re: I'm shocked with this picture.. help me

Post Fri May 23, 2008 2:18 am


dougj wrote:LOL - The only reason I might have gotten it right is because I was wearing my reading glasses....and read it a few times. My replies can be rather comical when I don't wear my glasses. Your new vote has been duly recorded Chris :mrgreen:


I made my first concession to be not young this am...
Yep reading glasses. I turn 45 in about a week.... wish me luck. :wink:

mnoble
 
Posts: 135

Re: I'm shocked with this picture.. help me

Post Fri May 23, 2008 10:43 am


Definitely "Hot Pixels." Google the term and you can get a pretty good explanation of the anomaly.

alikirk
 
Posts: 4

Re: I'm shocked with this picture.. help me

Post Fri May 23, 2008 12:53 pm


I agree with the above... hot pixels!
Easy enough to clone out - but I would take camera back to retailer.

nikgr
 
Posts: 71

Re: I'm shocked with this picture.. help me

Post Fri May 23, 2008 5:40 pm


These are HOT pixels.

When you go for long exposures then turn NR on.
NikGr
Nikon D300, Nikon D70, Nikon 990.

My Gallery
http://www.pbase.com/nikgr

rojay
 
Posts: 4

Re: I'm shocked with this picture.. help me

Post Wed May 28, 2008 10:07 pm


....maybe hot pixels caused by cosmic radiation. :)

carylwithay
 
Posts: 32

Re: I'm shocked with this picture.. help me

Post Fri May 30, 2008 3:08 pm


Call Nikon themselves. I have always found them to be helpful. I have the same camera and have never had those spots. They do seem like mistake.
Caryl
see my gallery at: pbase.com/carylwithay

jestev
 
Posts: 398
Location: Dallas, TX

Re: I'm shocked with this picture.. help me

Post Sun Jun 01, 2008 7:44 pm


I'd say hot pixels.

Also, the EXIF says it was 76 seconds -- not that should make a huge difference, however.
John Stevenson
http://www.pbase.com/jestev
Nikon N70, N6006; D300, D50
Lenses (of 20): Nikkor AF-S 17-55mm f/2.8G ED-IF, Tokina AT-X 12-24 f/4 AF PRO, Nikkor 80-200mm f/2.8D ED AF, Nikkor 50mm f/1.8D AF, Micro-Nikkor 55mm f/3.5 AI
Canon S1 IS
Minolta XG-7

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