Why does Nikon warn about banding at high ISOs when using autofocus on Nikon D4 or D800?

Question

Nikon says that banding may occur at high ISO sensitivities with autofocus on the D4 or D800:

D800

Noise in the form of horizontal lines may appear in pictures taken with AF-S Zoom Nikkor 24-85 mm f/3.5-4.5G (IF) lenses at ISO sensitivities over 6400; use manual focus or focus lock.

D4

Noise in the form of lines may appear during autofocus at high ISO sensitivities. Use manual focus or focus lock. Lines may also appear at high ISO sensitivities when aperture is adjusted during movie recording or live view photography.

What would explain this behavior?

Asked by DragonLord

Answer

This problem is caused by electromagnetic interference generated by the SWM in many Nikon lenses.

There are cases where Canon lenses with USMs have caused banding. See this dpreview forum thread for an instance of sensor banding caused by a USM lens mounted on a Canon DSLR.

Answered by DragonLord

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What does shot noise in color images look like?

Question

I can find examples of shot noise in monochrome images, but I can't find any examples in color images. What does shot noise in color images look like?

Asked by DragonLord

Answer

Exactly the same. Both CCD and CMOS sensors - with the exception of Foveon sensors - are achromatic. Color is created by an array of color filters in front of the sensor, so the shot-noise is the same, only you tint each pixel Red, Green or Blue. A few rare cameras also use Emerald tint and some leave one sub-pixel achromatic.

Answered by Itai

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What is “ISO” on a digital camera?

Question

What is "ISO" in general, and how is the scale defined?

How does the ISO scale for film speed differ from ISO sensitivity as used in digital cameras?

Is lower ISO always better?

Asked by mattdm

Answer

In photography, ISO generally refers to a measure of "Film Speed", which I use including reference to digital sensor sensitivity.

In short, the actual letters ISO are a name for the International Organization for Standardization (not, officially, an acronym -- more information here), and in photography it refers to the ISO 12232:2006 standard and other related standards: ISO 12232:1998, ISO 5800:1987, ISO 6:1993 and ISO 2240:2003. (Links on the Film Speed page.) Film historically has also used the ASA and DIN standards, the former using the same numbering system, and DIN using an entirely different scale.

The standards for film and digital are technically different (in ways I haven't investigated closely enough to report fully on), but generally they're similar enough that for practical purposes, they're essentially the same (notwithstanding Reciprocity Failure, which many films are quite prone to, though digital generally is not). So if you measure an exposure with your digital camera, you could use that exposure with a film of the same rating as the ISO setting you used in the digital camera, and expect to get a similar exposure (unless the shutter speed long or short enough for Reciprocity Failure to kick in for the film) (also assuming similar equipment otherwise -- no differences in filters, etc.).

In both digital and film, a higher number indicates greater sensitivity. A number twice as high is twice as sensitive (e.g. 200 is twice as sensitive as 100, 400 twice as sensitive as 200, etc.). So, when shooting in relatively low light, and wanting a relatively-fast (e.g. fast enough to stop motion) shutter speed, a higher sensitivity rating will be essential (so no, lower is not always better!)

In digital cameras (and similarly but differently in film), higher ISO ratings tend to create noise (the related effect in film is increased graininess). So, while it's not always better (that depends on what you're going for), lower ISO ratings are always (or at least almost always) lower in noise, which may be desirable. (In the case of low light photography where shutter speed is not a concern, long exposures mixed with lower ISO ratings will create a "better" image -- though it's conceivable that some may like the effects of the noise; certainly there's appeal at times to film grain.)

As for how the scale is defined, it is based on measurements of an image produced based on a certain scenario of illumination. The details are complex, so I'll leave the details as an exercise for the reader. A lay summary is that (for digital) it's a measure of how quickly the digital sensor becomes "saturated" with light. (For film, the process is related but different.)

In summary: higher ISO is more sensitive but noisier (but not necessarily worse), digital and film rated for the same ISO (or ASA for the film) will have similar sensitivity, and the scale is based on how quickly an image will become "saturated" given a certain amount of illumination.

---

NOTE: I'm gearing up to do some experimentation related to the controversial answer from Matt Grum. Hopefully, my results will create a nice clear noise-free answer to the important point he brings up: that a high-ISO image with a low amount of light will be less noisy than a low-ISO image with the same amount of light getting to the sensor, which is later amplified in post-processing. More to come, hopefully in... EDIT: Well, I've failed to make this happen for a while now. I may still do it at some point. In the mean time, I'll also point to this article that talks about comparisons of native versus non-native ISO values, and amounts of noise in them, which, while the article doesn't exactly say so, I think is probably directly related to exactly this question.

Answered by lindes

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How to minimise the noise when shooting primarily under candle lights?

Question

The following shots are with a small white light throwing "emergency light" on a height of one and a half forearms.

I used 3 candles on left side and 1 candle on the right.

Used 3 candles on right side.

Used 1 candle in the center, and 3 candles somewhat far on a stool.

Where to place how many candles to avoid noise?

The shots are from Nikon D3100, with ISO 200 at F1.8.

Asked by Anisha Kaul

Answer

I don't think these pictures are particularly noisy, although there is some in the shadow areas. While digital noise isn't as attractive as film grain, I think that in many ways it adds to the aesthetic appeal of this kind of low-light photograph. It's part of the vocabulary of photography, and we expect to see some.

If you do want to make the image as noise free as possible, as Matt Grum often tells us, don't be afraid of high ISO. This will give you a better signal-to-noise ratio for the same image exposure value.

Also, one of the reasons digital noise is less attractive than film grain is that it tends to produce colored speckles. That's one of the reasons I suggest converting to black and white in my answer to Is it practical to shoot portraits by only candlelight?. However, I don't think chroma noise is a big problem in your photograph, so if you like the black and white, it might be largely for other reasons:

That loses some of the warmth of the color version, though.

As an aside, I think you've focused a bit too closely in this image; I'd rather see more of the candle in focus. If you increase the ISO, you may want to also consider stopping down a bit for greater depth of field, although that's clearly a stylistic choice. I'd also really like to see more detail in the flame and in the area right around the flame — but that's off topic for this question and right back to Is it practical to shoot portraits by only candlelight? (or maybe a separate new question on candle flames themselves).

Answered by mattdm

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Is there software for detecting noisy areas in a photograph?

Question

I have been told that this photograph contains noise and is muddy. It is difficult for me to identify noise in a photograph until it is in extremes.

Are there any softwares available which detect the noisy areas in a photograph?

Asked by Anisha Kaul

Answer

I'm not aware of any software whose purpose is to simply alert you to noise. There are noise removal tools to remove noise though, and thatsoftware will show before and after the noise reduction.

Your image doesn't immediately strike me as noisy. However it's a dark image, and shadows is where you usually find noise.

To see the noise, it's best to zoom in to 100-200%, since noise is at the pixel level and you want a lot of magnification to see individual pixels.

Below is a small bit of your original image. You can see that the transition from light to dark isn't really smooth. You can see spots. I think they look "blocky" which means they may be more due to JPG compression rather than sensor noise. It's hard to see, but these spots are not just a pixel or two, but blocks of pixels as far as I can tell.

Applying a small amount of noise reduction to the image gives the following result, which is a lot smoother. It's removed the spots, whether they were JPG artifacts or actual noise. Whether you can tell the difference looking at the full image at normal resolution is debatable. If you can't easily see the noise, and have to magnify to 200% to find it, in my opinion it doesn't really matter.

Answered by MikeW

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Software for detecting noisy areas in a photograph

Question

I have been told that this photograph contains noise and is muddy. It is difficult for me to identify noise in a photograph until it is in extremes.

Are there any softwares available which detect the noisy areas in a photograph?

Asked by Anisha Kaul

Answer

I'm not aware of any software whose purpose is to simply alert you to noise. There are noise removal tools to remove noise though, and thatsoftware will show before and after the noise reduction.

Your image doesn't immediately strike me as noisy. However it's a dark image, and shadows is where you usually find noise.

To see the noise, it's best to zoom in to 100-200%, since noise is at the pixel level and you want a lot of magnification to see individual pixels.

Below is a small bit of your original image. You can see that the transition from light to dark isn't really smooth. You can see spots. I think they look "blocky" which means they may be more due to JPG compression rather than sensor noise. It's hard to see, but these spots are not just a pixel or two, but blocks of pixels as far as I can tell.

Applying a small amount of noise reduction to the image gives the following result, which is a lot smoother. It's removed the spots, whether they were JPG artifacts or actual noise. Whether you can tell the difference looking at the full image at normal resolution is debatable. If you can't easily see the noise, and have to magnify to 200% to find it, in my opinion it doesn't really matter.

Answered by MikeW

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Does size reduction in a fine quality JPEG photograph introduce noise?

Question

Does size reduction in a fine quality JPEG photograph introduces noise?

I use Gwenview to reduce the size of the JPEG photographs. Does that cause some noise introduction?

Asked by Anisha Kaul

Answer

In essence, no. That is, if you are referring to grain like noise such as what you see with higher ISO images. What you have with saving/resaving jpegs (especially at diffrerent quality levels) is artifacting. You can read about it here: http://en.wikipedia.org/wiki/Compression_artifact. The more aggressive the compression with jpeg the more data is thrown away (as mentioned in the earlier answer) and thus more visual artifacts are created.

I'm not familiar with the tool you mention but the best thing is use a higher quality setting (if available) for images that have lots of smooth areas (as those tend to be areas that get artifacts) or for ones with lots of detail you want to make sure is in the final image.

Answered by nwcs

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Where does the noise come from in a long exposure?

Question

I created another test. This time I exposed for 36 minutes, because I wanted to test star photography. This is not meant to be a nice photo; I really just tested.

Camera was inside the house behind the window (it is too cold to go out) in dark. Minimal light from other room came from behind the camera. It is a Canon EOS D1000 set on BULB, F29, ISO800

The question is: Where do the blue and red dots (noise) come from?

Answer

Well, perhaps you should have gone out after all :)

The noise is thermal noise, which will become noticeable as your sensor heats up during a long exposure. In astrophotography, it's quite a common problem.

Some ways to reduce such noise:

• cool sensor down, e.g. by shooting in the cold weather. Note that cold also negatively affects battery life.
• set the camera to take a dark frame with same settings (to get just the noise) and subtract it from the image; this can be either done manually (taking a second frame with lens cap on) or automatically by camera (the feature is called Long Exposure Noise Reduction or something similar).
• using a stronger noise reduction setting in camera; this may also make the photo softer overall.

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Which factors are responsible for making a photograph zero noised when scaled to 100%?

Question

While purchasing a DSLR which factors should be kept in mind if your aim is to zoom your photograph to 100%, frame it, and hang it on a wall?

At 100% there shouldn't be ANY noise.

Answer

Noise is like death and taxes, it is unavoidable.

Even the most expensive cameras produce noise and, although, it may only be visible at 100%. The base ISO, usually between 100 and 200 is almost noise-free, but you will still see noise in images, particularly in shadow areas.

What strikes me as odd about your request is that 100% scale can give you very different print sizes depending on the camera and print resolution. If you print an image at 300 DPI from a 8 MP DSLR, you will give a MUCH smaller print than an image from a 24 MP DSLR printed at 180 DPI.

What happens to noise is that it gets averaged-out and becomes visibly diminished when images are scaled down, so if you have extra pixels and can afford to scale down for the print size you want, you will be better off in terms of noise.

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What is the source of excessive noise in images from my D7000?

Question

I'm a beginning photographer who recently invested in the following setup:

Nikon D7000 camera body, 15-105mm Nikor kit lens, 150-500mm Sigma lens.

We recently made a trip to the Pantanal, Brazil where we made heavy use of the Sigma lens. Upon returning home, we noticed that those photos contain an excessive amount of noise. Below is an example of an unprocessed photo:

As you can see, even without zooming in particularly the unsharp areas have serious noise. And as I usually up the contrast of such an image, the noise gets even worse. I shoot mostly in aperture mode, and in this case the ISO was at 640, in order to be able to have a shutter speed that allows me to shoot without a tripod (other meta: F6.3, focal 500mm, 1/320s). Still, the D7000 is known to be able to handle high ISOs quite well, so I'm surprised to see this kind of noise at this ISO already.

I know how to get rid of noise, using both Lightroom and Noise Ninja, but the amount is so excessive that via luminance I'm losing too much detail. So my question is what the source of this noise is. Is it a natural limitation of my lens? Too little light available? Is it due to the 640 ISO? Is it due to me or some setting I'm overlooking?

Answer

I think that image is somewhat underexposed and that's half the problem. You might do better to use a higher ISO, and move the histogram to the right. Most of that image is in the lower half of the histogram.

I've read assertions that multiples of the base ISO, so 200, 400, 800 and so on are less noisy than intermediate values like 320 or 640. I don't know if that's true or not, perhaps a myth.

Even with a a camera like the D7000, dark areas are going to contain some noise, even between 400 and 800, especially if you try to lighten them in post processing.

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Does the order of sharpening and noise reduction matter?

Question

I have been shooting for more than three years, but I never do too much in post-processing. I tend to be strict and keep in mind that PP can only do little to save an otherwise-great photo.

I was going to enter the "Photo of the week" thing, and I was doing sharpening and noise reduction in Photoshop.

NR makes your photo blurry, while sharpening amplifies noise.

I wonder, does the order of these operations matter at all?

Should I apply noise reduction and then unsharp mask, or the other way round?

Answer

Simple answer is YES!

Noise is an undesirable artifact, and many operations can enhance its appearance, not just sharpening. Tweaking curves, adjusting contrast, working exposure, etc. can all have some impact on the noise that is present in an image...although sharpening tends to have the greatest impact. It is important to handle the bulk of your noise reduction as one of the first steps of your development workflow. You should not necessarily aim to "eliminate" all noise...rather your goal should be to reduce the effect noise has on an image as much as possible without adversely affecting detail that you wish to keep. The tool you use to remove noise can have a HUGE impact on the results as well...Photoshop in particular is not really known these days as having the best noise reduction tools. Lightroom has some fairly excellent noise reduction, and there are other tools like Noise Ninja and Neat Image that also do an excellent job.

Keep in mind your final presentation format and size...a LOT of noise that may be present in an image at 100% is going to get "absorbed" (for lack of a better term) into the final presentation format. Prints can sometimes exhibit pronounced noise, particularly when the noise contrasts well with the base image. Usually a moderate amount of noise, particularly in smooth gradients, can be beneficial to final print output as it normalizes content and eliminates harsh transitions. Presentation on a computer screen is often best done at significantly lower resolution than the original image, and downscaling is a superb mechanism for eliminating noise. If you start out with a moderate amount of noise, or an even distribution of high amounts of noise, downscaling for display on a computer screen (i.e. via a web page) can be all the noise reduction you need.

Sharpening is a facet that is closely linked to the viewing medium of an image. Generally speaking, its best to save sharpening for last. Not only that, its best to keep sharpened images saved as separate files from your primary work image (which in turn should be separate from your original master image.) The amount of sharpening done, and the type of algorithm used and its settings, should be matched to the output medium for your photos. If you intend an image to be viewed onscreen, the kind of sharpening you do will be different than if you intend to print. The size of the final image for either medium will also affect how much sharpening you do, and how that sharpening is done. It's a good best practice to save resizing, cropping and sharpening for the very last two steps of your image editing. Duplicate, crop, resize, sharpen. If sharpening greatly enhances the remaining noise in your image, you may also want to do a final "light" pass of noise reduction to minimize it as much as you can without adversely affecting sharpness.

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Why is my RAW import not displaying properly?

Question

I normally take my shots in RAW and normally work happily with them in Gimp on Linux. I have recently moved to a new shiny Windows laptop with Photoshop.

I have imported some shoots using Lightroom 3 but I am not seeing a faithful representation of the image either in LR nor in PS proper.

An example of the problems I am seeing can be seen in this image:

I have installed the latest Canon codecs for my camera (crc_1_8_0_68).

If I view the image on my camera's LCD screen I can zoom in and whilst there is a little noise this is nowhere near as bad as that seen in the above image.

What should I check to further diagnose this problem?

Answer

The image you see on the LCD is not the Raw image: it is a JPEG preview of it. Therefore it has had noise reduction, sharpening, and colour adjustments applied to it by the camera, just like a JPEG would if you had the camera set to record the shots as JPEGs.

Only when you import the photos to your PC will you see the actual Raw file without any (or at least low level) noise reduction etc. applied. It is up to you to apply these settings in LR or ACR.

I suspect that the RAW editor in GIMP was automatically applying noise reduction settings you'd previously used, hence you weren't used to seeing it on your old system.

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What is causing increased noise in my recent photos?

Question

In the last two shoots I've taken I have noticed much more noise in the resulting photos. In the first instance, I put this down to my fault, as I was shooting at high ISO levels, but in the second case I overcompensated and went to a very low ISO level.

Now, this could be a software thing — I've only just started using Adobe Lightroom and Photoshop, having been using Gimp for several years — but that doesn't sound likely. I've tried the noise reduction tool in LR but could not get a satisfactory result.

Equally unlikely, to me at least, is that the CF card has changed. I was running low on space during my days out with the camera and so changed my 1GB CF to a 4GB number. Could this be the culprit?

My camera is an EOS 30D and the lens in both cases was a Sigma 18-125mm 3.5-5.6

What could be causing this to suddenly start happening? Is there anything I can do to rescue the photos?

It might not be noise I'm seeing but something else. The background is certainly speckled which I've always assumed was noise but more worryingly is the loss of detail I'm seeing in certain areas — it's as if a low quality JPEG has been rendered from the image. The same region, when viewed in the camera's LCD, has plenty of detail in place.

The image is in RAW format and the lower ISO mentioned above was compensated for by using a flash.

Answer

High ISOs don't cause noise, lack of light causes noise. If you decrease the ISO without doing something to address the level of incoming light (note if you shoot in one of the auto modes your camera will do this for you) your signal to noise ratio will get worse.

There are a few other contributory factors, for example if the sensor is left on for a long period of time and becomes hot e.g. using live view then noise can increase.

Your post processing regime also contributes, if you pull the shadows up a lot then you will see a lot more noise.

But the major contributory factors in noise are "shot noise" due to the random emission of photons from a light source and not collecting enough photons to even out the randomness, and electrical noise, from the

Both of these get better with more light (by capturing more photons the signal produced is stronger with respect to the electrical noise). The fixes are to use a longer shutter time (and tripod if necessary), open the aperture more, or use an external source of light such as a flash.

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How can I keep my camera cool on a budget?

Question

Is there a way to cool the camera without buying a new hardware? How do you determine that the camera is NOT cool ATM? What temperature can be considered hot for the camera sensor? Does cooling really reduce the noise in the pictures?

Answer

In general, the camera's manual will tell you the operating temperatures for the camera.

Like all pieces of electronics, excessive heat isn't good for it. That said, I've only seen anecdotal evidence of heat adversely affecting image quality. It seems more common for batteries to stop working.

As for noise, you're probably going to have this issue in broad daylight, maybe in a desert. Your problem will be to get less light to the sensor, not worry about low light levels where noise is usually a problem.

I'd get a decent camera bag, in a lighter colour, and keep my gear in the shade whenever possible. Avoid using icepacks or similar or you will probably get problems with condensation.

Cooling is used in astrophotography, but those sensors are mostly CCD's, and the exposure times and low light levels are an order of magnitude longer and lower, respectively. I don't know whether CMOS sensors have the exact same issues as CCD's with heat when used for long exposures.

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When shooting HDR, is it better to use RAW images or jpgs?

Question

I just recently started shooting HDR images, and I like the effect when it's done right. I was just wondering, when I take 5 bracketed images and tonemap them using Photomatix Pro, is it better for me to just give the program the 5 RAW images, or should I convert them all to JPEG before tonemapping? Sometimes it seems like the tonemapping process adds a lot of noise that wasn't previously there, and I didn't know if perhaps using RAW images caused that. If you want to see the HDR images, feel free to view my G+ profile. Thanks!

Answer

Firstly you can produce HDR images with either raw or JPEG. However as raw files contain greater dynamic range than JPEGs to begin with it makes sense to shoot raw if you plan to produce HDR images, as you'll get better results.

To expand on your point about noise here is an important relationship between dynamic range and noise. Simply put dynamic range of a camera is the ratio between the brightest and darkest things the sensor can capture. The limit on how bright an object you can capture with digital is simple - it's the point at which the sensor pixels become saturated (full) after which an extra light does not affect the signal.

The limit on how dark an object you can capture is more complicated. You ought to be able to go darker and darker until there are no longer any photons being reflected from your object into the camera. However, there is a base level of noise you get even when the camera is not exposed to light. As you photograph darker and darker objects there will then come a point where all detail in the object is lost to noise.

The dynamic range is thus determined by noise, but more importantly noise and DR are inverses of each other! The noisier the camera the lower the dynamic range and vice versa.

What's happening when you're tonemapping is that the software (which has the job of taking a true high dynamic range image and squashing that down into a standard dynamic range image suitable for display on regular screens) is pushing the captures too far in order to even out brightness variations and you're seeing a lot of noise. The solution to this is to extend the dynamic range of the data you're working with, as we've established this will lead to less noise. The way to do that is to increase the range of camera exposures by capturing more images, or moving your 5 bracketed images further apart.

The fact has other consequences too. Your HDR image doesn't have to have the mega contrasty painting look that many people object to, it's possible to use HDR techniques to produce an ordinary looking image, but with exceptionally low noise!

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This doesn't seem very sharp…is this normal?

Question

Body: T2i Lens: Kit, 18-55mm f3.5-5.6

I went to shoot a sunrise this morning at the beach and got some great pictures, but when I uploaded them to some light post-processing, I was slightly surprised by how unsharp it was, and the amount of noise there was when I zoomed in. Is this normal for this camera/lens? My settings for the photo attached were 1/25, f4.0, ISO 100, and focus was set on the chair. My assumption is that it has something to do with the amount of available light, but I've seen plenty of sunrise/sunset pictures that are almost impossibly sharp.

Full-size

Answer

The Canon EF-S 18-55mm Kit lens is not the sharpest lens known, not if you're judging the pic at 100%. But when you're using smaller version of the image, sharpness is acceptable. Your example image looks sharp enough to me in this size, for a kit lens, its a good result.

Now, the noise. Its a very complicated term. It depends on a lot of things, one of them is wavelength of the light, or you can say color of the light. Blue channel is the noisiest channel and green is the least. Your sky is mostly blue and looks like that's the cause of the noise you're seeing.

You did not mention if you shoot raw or jpeg. jpeg images converted from raw provides better sharpness comparing to in camera jpeg. Also, T2i has a very powerful sensor, it's image quality increases a lot more when you use it with a superior lens. So, if you're not happy with it, try getting a lens known for its sharpness (rent for a day or ask a friend), shoot with it and check if it makes you happy or not.

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Why is there so much noise in RAW files from my new Canon 7D?

Question

I recently bought a Canon 7D, upgrading from a 50D. I was blown away by what I saw on the back of the camera after I took a few shots.

Now that i've taken the time to import the photos into lightroom & DXO... I'm finding the noise level to be very high, even on low ISO shots I find myself dealing with much more noise than I'm used to.

Has anyone experienced this? Are there any solutions?

I've had this camera for two days and I'm already thinking of selling it... if I can't find a solution for all this noise.

Edit: After some discussions, and comparissons, jpg files rendered by the body look great. I'll just have to get used to post processing a bit more.

I also foudn out that for the best results use multiples of 160 ISO. (I need to test this)

Answer

Because of the pixel density I would say. Your 50D had the highest pixel density in Canon's lineup when it was released, at 4.5MP/cm2. At that density the lens becomes the limiting factor, you need good glass. A few reviews pointed out that the image quality of the 50D wasn't much better than the 40D it was replacing actually, with a density of 3.1 MP/cm2. This is even more true for the 7D, which topped the 50D with a 5.4 MP/cm² density. For reference, the full frame Canon 5D II is at 2.4 MP/cm2.

From a theoretical point of view pixel density should affect the amount of random digital noise and the dynamic range in the image the camera produces. Granted, a lot is going on under the hood in the 7D to reduce/fix this "limitation", but that could be why you feel there is more noise in your 7D than in your 50D.

I have a 5DMII. Friend of mine bought a 7D. We tested in a room I had used my 5DMII in, and I was surprised by the noise myself, it didn't have the same "quality" as what I would see on the 5DMII. Granted, we should have put my L lens on his 7D, instead of his kit lens. He sold it to buy a 5DMII.

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Is it me or is the Lightroom's zoomed out preview inaccurate in displaying noise and color?

Question

I'm having some trouble with the Lightroom viewer (In develop mode) when zoomed out. Look at this picture:

See how the sky seems to have a lot of chroma noise

Now check the zoomed in version (Of the sky part)

I can't see any (significant) chroma noise here!

Finally, check this side by side comparison: Lightroom (RAW original file) and Windows image viewer (Exported JPG, 100 quality) (Click here for the full size version)

The windows image viewer shows a much better sky, without all the "blotches" of color and strong noise that the LR version shows. Do I have something wrongly configured? Do you suffer the same issue?

Answer

I don't use Lightroom but I regularly use Adobe Camera Raw which is pretty much the same thing but built into Photoshop, and have observed the same effect.

By default ACR applies chroma noise reduction to the raw image. The noise reduction only seems to be applied in the preview when you zoom in (perhaps Adobe figured the noise wouldn't be visible in the zoomed out view due to resampling), so what you're seeing in the zoomed out version is the actual noise level, and what you're seeing zoomed in is what it looks like after Lightroom has smoothed the noise.

You could confirm this by turning off noise reduction in Lightroom and seeing if you get the same result zoomed in as zoomed out.

As soon as you export to JPEG the noise reduction is applied to the whole image, which is why you don't see it in the Windows Photo Viewer.

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