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#1
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Bands noted in dark frames of Nikon D70 long exposures
I attempted to take some long-exposure Milky Way photos last night. I am
experienced at astrophotography with film and specialized astrophotography ccd cameras but tried using the D70 for the first time for this purpose last night. My problem is that I am noticing severe bands or lines in the images. This has not been noted in any of my other photos...just these dark shots. You can see what I'm describing at the below links. This is my Milky Way shot in which you can see some differently shaded bands. http://astroimages.org/MilkyWay-merge.jpg The shot above is the result of layering 10, 30-second shots using Paint Shop Pro. To see the effect, I shot a 30-second dark frame (lens cap on) and adjusted the gamma up to 2.7 to bring out the effect. The below link contains that result with clear bands of light and dark. http://astroimages.org/DSC_0002.jpg To repeat this experiment, set your camera to take a 30" image, and leave the lens cap on. Load the resultant image in your favorite processing program (I use PSP9) and boost the gamma (I used 2.7 in PSP9). I also ran a test with covering the viewfinder to ensure that it wasn't somehow connected to stray light getting through. Does anyone have any ideas about what I am observing? Could someone run the same dark frame test described above to confirm whether it is something inherent in D70's or just my camera? Is there a workaround if it is common to all of these cameras? Thanks for any help that anyone might provide. Jeff |
#2
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I should also point out that I was shooting in .raw mode and had noise
reduction set to off. However, I've retried my experiment using .jpg fine and also turning NR to on and although it changes the effect somewhat, it is still present. Jeff "Jeff M" wrote in message ... I attempted to take some long-exposure Milky Way photos last night. I am experienced at astrophotography with film and specialized astrophotography ccd cameras but tried using the D70 for the first time for this purpose last night. My problem is that I am noticing severe bands or lines in the images. This has not been noted in any of my other photos...just these dark shots. You can see what I'm describing at the below links. This is my Milky Way shot in which you can see some differently shaded bands. http://astroimages.org/MilkyWay-merge.jpg The shot above is the result of layering 10, 30-second shots using Paint Shop Pro. To see the effect, I shot a 30-second dark frame (lens cap on) and adjusted the gamma up to 2.7 to bring out the effect. The below link contains that result with clear bands of light and dark. http://astroimages.org/DSC_0002.jpg To repeat this experiment, set your camera to take a 30" image, and leave the lens cap on. Load the resultant image in your favorite processing program (I use PSP9) and boost the gamma (I used 2.7 in PSP9). I also ran a test with covering the viewfinder to ensure that it wasn't somehow connected to stray light getting through. Does anyone have any ideas about what I am observing? Could someone run the same dark frame test described above to confirm whether it is something inherent in D70's or just my camera? Is there a workaround if it is common to all of these cameras? Thanks for any help that anyone might provide. Jeff |
#3
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I should also point out that I was shooting in .raw mode and had noise
reduction set to off. However, I've retried my experiment using .jpg fine and also turning NR to on and although it changes the effect somewhat, it is still present. Jeff "Jeff M" wrote in message ... I attempted to take some long-exposure Milky Way photos last night. I am experienced at astrophotography with film and specialized astrophotography ccd cameras but tried using the D70 for the first time for this purpose last night. My problem is that I am noticing severe bands or lines in the images. This has not been noted in any of my other photos...just these dark shots. You can see what I'm describing at the below links. This is my Milky Way shot in which you can see some differently shaded bands. http://astroimages.org/MilkyWay-merge.jpg The shot above is the result of layering 10, 30-second shots using Paint Shop Pro. To see the effect, I shot a 30-second dark frame (lens cap on) and adjusted the gamma up to 2.7 to bring out the effect. The below link contains that result with clear bands of light and dark. http://astroimages.org/DSC_0002.jpg To repeat this experiment, set your camera to take a 30" image, and leave the lens cap on. Load the resultant image in your favorite processing program (I use PSP9) and boost the gamma (I used 2.7 in PSP9). I also ran a test with covering the viewfinder to ensure that it wasn't somehow connected to stray light getting through. Does anyone have any ideas about what I am observing? Could someone run the same dark frame test described above to confirm whether it is something inherent in D70's or just my camera? Is there a workaround if it is common to all of these cameras? Thanks for any help that anyone might provide. Jeff |
#4
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I should also point out that I was shooting in .raw mode and had noise
reduction set to off. However, I've retried my experiment using .jpg fine and also turning NR to on and although it changes the effect somewhat, it is still present. Jeff "Jeff M" wrote in message ... I attempted to take some long-exposure Milky Way photos last night. I am experienced at astrophotography with film and specialized astrophotography ccd cameras but tried using the D70 for the first time for this purpose last night. My problem is that I am noticing severe bands or lines in the images. This has not been noted in any of my other photos...just these dark shots. You can see what I'm describing at the below links. This is my Milky Way shot in which you can see some differently shaded bands. http://astroimages.org/MilkyWay-merge.jpg The shot above is the result of layering 10, 30-second shots using Paint Shop Pro. To see the effect, I shot a 30-second dark frame (lens cap on) and adjusted the gamma up to 2.7 to bring out the effect. The below link contains that result with clear bands of light and dark. http://astroimages.org/DSC_0002.jpg To repeat this experiment, set your camera to take a 30" image, and leave the lens cap on. Load the resultant image in your favorite processing program (I use PSP9) and boost the gamma (I used 2.7 in PSP9). I also ran a test with covering the viewfinder to ensure that it wasn't somehow connected to stray light getting through. Does anyone have any ideas about what I am observing? Could someone run the same dark frame test described above to confirm whether it is something inherent in D70's or just my camera? Is there a workaround if it is common to all of these cameras? Thanks for any help that anyone might provide. Jeff |
#5
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On Sun, 7 Nov 2004 16:46:47 -0500, "Jeff M"
wrote: Looks to me to be pattern noise that you brought out with the dark field exposure. I don't know if the banding is common with the D70 but all ccd cameras have some pattern noise due to the variations in pixel sensitivity. And I believe there are a number of programs and procedures to subtract out pattern noise. You might try asking for details in the the astronomical news groups. I attempted to take some long-exposure Milky Way photos last night. I am experienced at astrophotography with film and specialized astrophotography ccd cameras but tried using the D70 for the first time for this purpose last night. My problem is that I am noticing severe bands or lines in the images. This has not been noted in any of my other photos...just these dark shots. You can see what I'm describing at the below links. This is my Milky Way shot in which you can see some differently shaded bands. http://astroimages.org/MilkyWay-merge.jpg The shot above is the result of layering 10, 30-second shots using Paint Shop Pro. To see the effect, I shot a 30-second dark frame (lens cap on) and adjusted the gamma up to 2.7 to bring out the effect. The below link contains that result with clear bands of light and dark. http://astroimages.org/DSC_0002.jpg To repeat this experiment, set your camera to take a 30" image, and leave the lens cap on. Load the resultant image in your favorite processing program (I use PSP9) and boost the gamma (I used 2.7 in PSP9). I also ran a test with covering the viewfinder to ensure that it wasn't somehow connected to stray light getting through. Does anyone have any ideas about what I am observing? Could someone run the same dark frame test described above to confirm whether it is something inherent in D70's or just my camera? Is there a workaround if it is common to all of these cameras? Thanks for any help that anyone might provide. Jeff |
#6
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On Sun, 7 Nov 2004 16:46:47 -0500, "Jeff M"
wrote: Looks to me to be pattern noise that you brought out with the dark field exposure. I don't know if the banding is common with the D70 but all ccd cameras have some pattern noise due to the variations in pixel sensitivity. And I believe there are a number of programs and procedures to subtract out pattern noise. You might try asking for details in the the astronomical news groups. I attempted to take some long-exposure Milky Way photos last night. I am experienced at astrophotography with film and specialized astrophotography ccd cameras but tried using the D70 for the first time for this purpose last night. My problem is that I am noticing severe bands or lines in the images. This has not been noted in any of my other photos...just these dark shots. You can see what I'm describing at the below links. This is my Milky Way shot in which you can see some differently shaded bands. http://astroimages.org/MilkyWay-merge.jpg The shot above is the result of layering 10, 30-second shots using Paint Shop Pro. To see the effect, I shot a 30-second dark frame (lens cap on) and adjusted the gamma up to 2.7 to bring out the effect. The below link contains that result with clear bands of light and dark. http://astroimages.org/DSC_0002.jpg To repeat this experiment, set your camera to take a 30" image, and leave the lens cap on. Load the resultant image in your favorite processing program (I use PSP9) and boost the gamma (I used 2.7 in PSP9). I also ran a test with covering the viewfinder to ensure that it wasn't somehow connected to stray light getting through. Does anyone have any ideas about what I am observing? Could someone run the same dark frame test described above to confirm whether it is something inherent in D70's or just my camera? Is there a workaround if it is common to all of these cameras? Thanks for any help that anyone might provide. Jeff |
#8
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Jeff M wrote:
I attempted to take some long-exposure Milky Way photos last night. I am experienced at astrophotography with film and specialized astrophotography ccd cameras but tried using the D70 for the first time for this purpose last night. Jeff, you might try joining the group. There are a lot of experienced astrophotographers there, many using a D70, who might be able to answer your question. Also, many spectacular astrophotos are posted. Truly outstanding work by many people. Roger My problem is that I am noticing severe bands or lines in the images. This has not been noted in any of my other photos...just these dark shots. You can see what I'm describing at the below links. This is my Milky Way shot in which you can see some differently shaded bands. http://astroimages.org/MilkyWay-merge.jpg The shot above is the result of layering 10, 30-second shots using Paint Shop Pro. To see the effect, I shot a 30-second dark frame (lens cap on) and adjusted the gamma up to 2.7 to bring out the effect. The below link contains that result with clear bands of light and dark. http://astroimages.org/DSC_0002.jpg To repeat this experiment, set your camera to take a 30" image, and leave the lens cap on. Load the resultant image in your favorite processing program (I use PSP9) and boost the gamma (I used 2.7 in PSP9). I also ran a test with covering the viewfinder to ensure that it wasn't somehow connected to stray light getting through. Does anyone have any ideas about what I am observing? Could someone run the same dark frame test described above to confirm whether it is something inherent in D70's or just my camera? Is there a workaround if it is common to all of these cameras? Thanks for any help that anyone might provide. Jeff |
#9
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#10
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