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Subject: "D7100 - Is this color noise?" Previous topic | Next topic
Steve6344 Silver Member Nikonian since 31st Jul 2012Fri 27-Sep-13 05:28 PM
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"D7100 - Is this color noise?"


Aventura, US
          

Below is a screenshot (Viewed at 1:1) from Lightroom of a 7200 x 4800 NEF. There are colored 'specks' in the small screenshot visible when viewed at 1:1.

Underneath the 'noisy' image is a screenshot of a larger portion of the image. The 'noisy' small screenshot is from the water part of the main image.

What are these spots? (I had my sensor cleaned about 4 weeks ago.)






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Attachment #1, (jpg file)
Attachment #2, (jpg file)

  

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Replies to this topic
Subject Author Message Date ID
Reply message RE: D7100 - Is this color noise?
elec164 Silver Member
27th Sep 2013
1
Reply message RE: D7100 - Is this color noise?
Steve6344 Silver Member
28th Sep 2013
2
     Reply message RE: D7100 - Is this color noise?
elec164 Silver Member
28th Sep 2013
3
Reply message RE: D7100 - Is this color noise?
aolander Silver Member
28th Sep 2013
4
Reply message RE: D7100 - Is this color noise?
Steve6344 Silver Member
28th Sep 2013
5
     Reply message RE: D7100 - Is this color noise?
jbloom Gold Member
28th Sep 2013
6
     Reply message RE: D7100 - Is this color noise?
elec164 Silver Member
28th Sep 2013
7
          Reply message RE: D7100 - Is this color noise?
Steve6344 Silver Member
28th Sep 2013
8

elec164 Silver Member Nikonian since 15th Jan 2009Fri 27-Sep-13 11:05 PM
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#1. "RE: D7100 - Is this color noise?"
In response to Reply # 0


US
          

The EXIF data is stripped and you provide limited information to make any determination.

What ISO and shutter speed was used?

It sort of looks like hot pixels from high ISO long exposure, but again with the limited information that’s just a stab in the dark. Another possibility is specular highlights off the water, but again limited information.

Pete

Pete

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Steve6344 Silver Member Nikonian since 31st Jul 2012Sat 28-Sep-13 01:11 AM
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#2. "RE: D7100 - Is this color noise?"
In response to Reply # 1


Aventura, US
          

Hi Pete, Thanks for responding.
ISO 100
f14
15 seconds
10 stop ND filter

What are hot pixels? Can they be avoided if that's what this is.
I don't use HI ISO noise reduction.

Thanks - Steve

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elec164 Silver Member Nikonian since 15th Jan 2009Sat 28-Sep-13 03:18 AM
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#3. "RE: D7100 - Is this color noise?"
In response to Reply # 2


US
          


>15 seconds
>
>What are hot pixels? Can they be avoided if that's what this
>is.

Hot pixels are a fact of life with digital imaging. Now knowing it was a 15 second exposure, hot pixel seems more likely the cause.

Generally it is caused by leakage current. It shows up with longer exposures due to thermal increase in sensor, even at base ISO (but becomes even more evident at higher ISO's).

It's a fixed pattern noise that can be dealt with through dark frame subtraction.

Pete

Pete

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aolander Silver Member Nikonian since 15th Sep 2006Sat 28-Sep-13 03:30 AM
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#4. "RE: D7100 - Is this color noise?"
In response to Reply # 0


Nevis, US
          

You could use Long Exposure Noise Reduction. See page 228 of your manual.

Alan

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Steve6344 Silver Member Nikonian since 31st Jul 2012Sat 28-Sep-13 01:18 PM
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#5. "RE: D7100 - Is this color noise?"
In response to Reply # 4


Aventura, US
          

Thanks all. I will try long exposure noise reduction the next time I do a long exposure. I'm not sure it's necessary because I don't see the noise when I look at a print at normal viewing distance. Do most people not use it because it doubles the time to take the image and they are not bothered by the noise?

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jbloom Gold Member Awarded for the continuous and generous sharing of his high level expertise and his always encouraging comments in several forums. Nikonian since 15th Jul 2004Sat 28-Sep-13 01:34 PM
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#6. "RE: D7100 - Is this color noise?"
In response to Reply # 5


Wethersfield, US
          

I don't know whether most people use it or not. Under most circumstances, I use it. After all, you are presumably already working slowly and deliberately since you're taking long exposures. What's the difference if they take twice as long?

There are exceptions, of course. If you have a need to take as many shots as possible in the available time or don't want time gaps between shots (shooting star trails comes to mind), perhaps you would rather have the hot pixels than the dead time between shots. But to me, those are exceptional cases.

-- Jon
Wethersfield, CT, USA
Connecticut High School Sports Photos

  

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elec164 Silver Member Nikonian since 15th Jan 2009Sat 28-Sep-13 09:10 PM
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#7. "RE: D7100 - Is this color noise?"
In response to Reply # 5


US
          

>Thanks all. I will try long exposure noise reduction the next
>time. Do most people not use it because it doubles the
>time to take the image and they are not bothered by the
>noise?

It depends.If you are only taking one or two shots, then the in camera dark frame subtraction (what Nikon calls Long Exposure Noise Reduction) is not to bad. But as already suggested, if you need many long exposure shots in a row and can't wait for that second dark frame time, then you could just take your own single dark frame during the shoot at the same exposure time, and then do the dark frame subtraction as needed later in an editor such as Photoshop.

Pete

Pete

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Steve6344 Silver Member Nikonian since 31st Jul 2012Sat 28-Sep-13 09:24 PM
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#8. "RE: D7100 - Is this color noise?"
In response to Reply # 7


Aventura, US
          

Usually I take several images with varying exposure times. I think I will give the long exposure noise reduction a try. I am happy that all of the responders helped me to identify the problem as I was not sure what I was dealing with. It didn't look like dirt or noise and I was unfamiliar with 'hot pixels' .
Thanks all.
Steve

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