Go Back   Sports Car Forum - MotorWorld.net > Hobbies and Leisure Time > Photography



Reply
 
Thread Tools Display Modes
Old 08-19-2008, 12:23 AM   #1
MidEngine4Life
Regular User
 
Join Date: Mar 2005
Location: San Jose, California
Posts: 1,126
Default Photo Help

I was doing a little experimenting with my camera today and took this minute long exposure. Can anyone tell me wtf is with all the little pixels? Is my lens dirty? Is my camera dying?
__________________
Clarkson: "Why have they never sold mustangs here?"
May: "Well, because they're rubbish"
MidEngine4Life is offline   Reply With Quote
Old 08-19-2008, 12:31 AM   #2
nthfinity
Regular User
 
Join Date: Jan 2004
Location: Detroit
Posts: 9,929
Default

first problem, you did a "Save for web" which killed the exif data... so no idea what camera you are using.

Second, it looks like your camera has some pixels which are over active when stimulated in long exposure for misc. values.

On my 20D, I had 4 or 5 pixels which did this, but always in a light grey value, not misc. RGB's like yours. I don't think your camera is dying, unless perhaps it is some upper model Canon or Nikon or something.

I think the technical name is "dead pixels" but its not the most accurate name, since it only happens on long exposure (same as when my 20D had the grey pixels.... which were only noticeable when flipping from one image to the next.)
__________________
www.nthimage.com
Car photography website
nthfinity is offline   Reply With Quote
Old 08-19-2008, 12:48 AM   #3
MidEngine4Life
Regular User
 
Join Date: Mar 2005
Location: San Jose, California
Posts: 1,126
Default

I just have it set up to save as jpg. Next time I do a long exposure do you think I should set it so save as a raw file?
__________________
Clarkson: "Why have they never sold mustangs here?"
May: "Well, because they're rubbish"
MidEngine4Life is offline   Reply With Quote
Old 08-19-2008, 01:00 AM   #4
nthfinity
Regular User
 
Join Date: Jan 2004
Location: Detroit
Posts: 9,929
Default

Originally Posted by MidEngine4Life View Post
I just have it set up to save as jpg. Next time I do a long exposure do you think I should set it so save as a raw file?
no, that shouldn't make any difference. I'm just curious what camera/lens/settings etc. in the exif data.

when you resized the image, were there fewer "HOT pixels" ?
__________________
www.nthimage.com
Car photography website
nthfinity is offline   Reply With Quote
Old 08-19-2008, 01:04 AM   #5
MidEngine4Life
Regular User
 
Join Date: Mar 2005
Location: San Jose, California
Posts: 1,126
Default

Yea in its raw large size before i resized it there were a lot more visible. Im using an Olympus E-500. I was using the "S" setting that lets me select the shutter speed while it compensates for the rest. Set it at the max of 60 seconds.
__________________
Clarkson: "Why have they never sold mustangs here?"
May: "Well, because they're rubbish"
MidEngine4Life is offline   Reply With Quote
Old 08-19-2008, 01:12 AM   #6
nthfinity
Regular User
 
Join Date: Jan 2004
Location: Detroit
Posts: 9,929
Default

Originally Posted by MidEngine4Life View Post
Yea in its raw large size before i resized it there were a lot more visible. Im using an Olympus E-500. I was using the setting that lets me select the shutter speed and it compensates for the rest. Set it at the max of 60 seconds.
OK

what is happening with long expsoures is the CCD ends up heating up, and more pixels become "hot" and expose in misc colors.

60 seconds is a LOT of expsure time. Tolerences change in mfr. spec with the more exposure time you have there is less mfr. spec for hot pixels... i hope that makes sense.

that said, the number is pretty outrageous IMO... seems you aren't the only guy with this issue

http://photo.net/olympus-camera-forum/00LYDX

In my canon, there is an option for "color noise reduction" on long exposure. It's already so low that I don't have this set on, even in bulb shots of 200 seconds (i've only done that a few times) ... where basically the software compares the noise in a normal exposed shot compared to the long exposure, and eliminates most of the hot pixels that would form.

so a bit of PS will solve your issue... but unfortunatley, it does seem normal
__________________
www.nthimage.com
Car photography website
nthfinity is offline   Reply With Quote
Old 08-19-2008, 02:37 AM   #7
unwilling
Regular User
 
Join Date: Jul 2006
Posts: 109
Default

would be a bomb photo minus those, as nth calls them, hot pixels
unwilling is offline   Reply With Quote
Old 08-19-2008, 02:59 AM   #8
MidEngine4Life
Regular User
 
Join Date: Mar 2005
Location: San Jose, California
Posts: 1,126
Default

Just dunno how to PS those out without using the clone tool on all 5 thousand of them lol
__________________
Clarkson: "Why have they never sold mustangs here?"
May: "Well, because they're rubbish"
MidEngine4Life is offline   Reply With Quote
Old 08-19-2008, 03:03 AM   #9
HeilSvenska
Regular User
 
Join Date: Dec 2003
Location: The OC™
Posts: 4,881
Default

You just need to take another picture. There's no other way than that.

So, was that in the middle of night or what? Minute long exposure must be insanely tedious.
__________________
HeilSvenska is offline   Reply With Quote
Old 08-19-2008, 03:27 AM   #10
MidEngine4Life
Regular User
 
Join Date: Mar 2005
Location: San Jose, California
Posts: 1,126
Default

It was shortly after sunset.I really need a new camera.
__________________
Clarkson: "Why have they never sold mustangs here?"
May: "Well, because they're rubbish"
MidEngine4Life is offline   Reply With Quote
Old 08-19-2008, 03:45 AM   #11
HeilSvenska
Regular User
 
Join Date: Dec 2003
Location: The OC™
Posts: 4,881
Default

^What'd you do to fix it? Clone?
__________________
HeilSvenska is offline   Reply With Quote
Old 08-19-2008, 03:46 AM   #12
MidEngine4Life
Regular User
 
Join Date: Mar 2005
Location: San Jose, California
Posts: 1,126
Default

Filter: Noise: Median + Clone + Resize
__________________
Clarkson: "Why have they never sold mustangs here?"
May: "Well, because they're rubbish"
MidEngine4Life is offline   Reply With Quote
Old 08-19-2008, 03:49 AM   #13
HeilSvenska
Regular User
 
Join Date: Dec 2003
Location: The OC™
Posts: 4,881
Default

Okay then. That works.
__________________
HeilSvenska is offline   Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump