Question: Nikon Noise Reduction

[Disles1]

My Nikon P7700 camera has three settings for noise reduction (low, normal and high) and I understand that the camera takes a second photo with aperture closed to adjust noise. What I don't know is whether the camera always takes a second photo, or only at high ISOs, and what the difference in processing is at lower ISOs such as 800 and slower? I understand that some detail is lost when NR is used but I don't know how much of a difference occurs at "normal" light conditions (i.e., versus very low light).

Would you set the camera at low NR for photos at 800 ISO and lower or keep it at normal?

[Mike Buckley]

Your camera's manual probably answers the questions you have asked about how the camera functions. Download the PDF and conduct a search on "noise."

I have always configured the setting in my Nikon camera bodies not to apply noise reduction. That's because I would rather deal with noise, if it exists, during post-processing using methods that are totally within my control.

Be aware that even if you disable in-camera noise reduction, all of my Nikon cameras will apply it to a relatively small extent at very high ISO values. Look for that detail in your camera's manual for a complete understanding of whether or not that happens when using your camera.

[Disles1]

Your camera's manual probably answers the questions you have asked about how the camera functions. Download the PDF and conduct a search on "noise."

Mike, the Nikon manual - nor an extended manual I purchased - doesn't say anything about the process; only that "normal" applies more than "low". It doesn't indicate when it applies the NR.

[DanK]

I understand that the camera takes a second photo with aperture closed to adjust noise.

Are you sure? I don't shoot Nikon, but on Canon cameras, there are two different types of noise reduction. Most cameras have a built-in firmware noise reduction algorithm to address noise from high-ISO shooting. On Canons, I think this affects only jpegs. It does not entail a second exposure, and reduces detail (as does software removal of high-ISO noise). The second type of noise reduction is for long exposures and is typically called long-exposure or subtractive noise reduction. This entails taking a second, black exposure and then subtracting the data from the second from the data from the first. This affects raw files and does not remove detail.

[Disles1]

Update - I found this statement under Nikon's articles "Another factor is the amount and type of noise reduction being applied in the camera. Because all pixels collect some noise, every digital camera runs processing on every image (although with a NEF, or RAW, file that can be changed later) to minimize that noise. Newer cameras use newer technology to reduce that noise, with the result being less noise at similar ISOs than what earlier cameras could achieve."

It seems therefore that Nikon cameras apply NR to EVERY image so the only adjustment would be the amount of NR applied.

http://www.nikonusa.com/en/Learn-And...nsitivity.html

[Mike Buckley]

In the case of your camera, I would always use the "low" setting, allowing me total control if more noise reduction is needed during post-processing.

[Manfred M]

Ken - I think you are confusing darkframe (long exposure) noise reduction with the level of noise reduction your camera applies during normal shooting. The high / medium / low settings only refers to the amount of pixel smearing that the camera applies when creating jpeg images.

For extremely long exposures (usually shots that are measured as a number of minutes), additional noise is introduced due to sensor heat. Here both the normal image is taken and then a subsequent image of equal length, with a closed shutter. The noise related to shooting with a hot sensor can then be isolated and subtracted from the resulting image. The technique works well, but doubles the time for each shot.

[Disles1]

Ken - I think you are confusing darkframe (long exposure) noise reduction with the level of noise reduction your camera applies during normal shooting. The high / medium / low settings only refers to the amount of pixel smearing that the camera applies when creating jpeg images.

For extremely long exposures (usually shots that are measured as a number of minutes), additional noise is introduced due to sensor heat. Here both the normal image is taken and then a subsequent image of equal length, with a closed shutter. The noise related to shooting with a hot sensor can then be isolated and subtracted from the resulting image. The technique works well, but doubles the time for each shot.

You are probably correct, Manfred. My camera doesn't have the two adjustments available on quality DSLRs (high ISO - Long Exposure) so I wonder if my camera has a default long exposure NR with adjustments available for high ISOs?

[Mike Buckley]

The high / medium / low settings only refers to the amount of pixel smearing that the camera applies when creating jpeg images.

That's a detail I had never noticed and is not mentioned in my Nikon D7000 camera manual in its discussion of noise reduction. However, your point is proven in my mind by the fact that opening a NEF using Nikon Capture NX2, which displays all in-camera processing, displays nothing pertaining to in-camera noise reduction. EDIT: I just realized that might be due to the fact that my camera is configured not to apply it. I'll set the camera to apply noise reduction later today and report the results.

[Manfred M]

You are probably correct, Manfred. My camera doesn't have the two adjustments available on quality DSLRs (high ISO - Long Exposure) so I wonder if my camera has a default long exposure NR with adjustments available for high ISOs?

I rather doubt it Ken; the darkframe noise reduction likely a feature that is limited to more advanced DSLRs, rather than the camera that you have. I would expect that you are likely limited to more traditional noise reduction techniques. The various noise reduction settings are more likely to be allowing you to trade off between sharpness and noise reduction amount (this is really also what happens in software based noise reduction).

I find that in a properly exposed image, noise is not an issue, even at higher ISO settings. If there is noise, it tends to be in darker, shadow areas and I will deal with that in the localized areas in post-production.

[ajohnw]

I rather doubt it Ken; the darkframe noise reduction likely a feature that is limited to more advanced DSLRs, rather than the camera that you have. I would expect that you are likely limited to more traditional noise reduction techniques. The various noise reduction settings are more likely to be allowing you to trade off between sharpness and noise reduction amount (this is really also what happens in software based noise reduction).

I find that in a properly exposed image, noise is not an issue, even at higher ISO settings. If there is noise, it tends to be in darker, shadow areas and I will deal with that in the localized areas in post-production.

I wouldn't be so sure about that Manfred. My Pen's do something without being asked and some Sony compacts have been doing something for rather a long time. On the Pen's it comes in even at a 10 sec exposure. E-P3 at least, not tried on the E-PL1.

I use the term do something as it's hard to be sure about exactly what is going on. There is a long period of card activity after the exposure. 2 things are possible. As you mention or say taking say 5 2sec exposures and adding them. As most cameras have buffers for storage it's hard to tell which. If they just wanted to account for thermal changes they mighty just take a dark frame just after the real one has been taken.

I've not tried long exposures on my D7000 but as I understand these use a Sony sensors so are likely to use the same techniques. Sony may have designed the sensors to be used in a certain way. They switched CCD development off a long time ago started beavering away on CMOS types. They are using additive exposures on some chips to extend dynamic ranges. Also noise reduction on the sensor itself. What isn't clear is how this relates to larger sensors in our range of sizes.

John
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[Mike Buckley]

I've not tried long exposures on my D7000

According to the manual, noise reduction is applied to exposures longer than 8 seconds but only if long exposure noise reduction is enabled.

[Manfred M]

Each camera seems to be a bit different; on the D800, the long exposure noise reduction kicks in at exposures over 1 sec (no that I have ever seen any noise issues at that shutter speed) and the high speed noise reduction kicks in at ISO 1600 and above (whereas I find even exposures taken at ISO 4000 seem to be quite clean).