This will show you a little of what Lightroom can do. This is an image I took recently. If memory serves me, I used highlight weighted metering to help preserve highlight detail because of the difficult lighting situation. The subject ended up badly underexposed. Low exposure levels are the real cause of noise, higher ISOs just turn up the volume to make the image look normal. For reference it was shot handheld at 1/2000 sec, F6.3, ISO 1800, 600mm an a full frame high resolution sensor. I could have shot at a lower shutter speed and decreased noise, but I didn't want to miss an action shot while trying to increase my shutter speed if the duck decided to flap it's wings or interact with another duck.
This is the final version. I ran the RAW file through Topaz to remove noise. This version will look a tad over processed, if you blow it up to extremes, but looks natural, IMO, at normal viewing magnification. I should probably decrease the saturation a tad in the head and top of the wings to make it look more natural.
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This is an extreme blowup of the subject without any processing at all. It's very dark and very noisy.
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I did some minimal processing in Lightroom to make it easier to see details
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This version, I ran through Lightroom's automatic de noise. IMO, it does a very good job, but is very slow on my computer. It often takes as long as 10 to 15 minutes to process a single image. I have seen it run much quicker on other computers. Topaz takes only a couple minutes to process an image on my computer.
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This is a huge improvement, but there is still some noise, so I used the slider to increase the amount of de noise applied. This is the result. Keep in mind that this is far more detail than anyone would ever see, unless you blow this up to a huge print, or very extreme crop.
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In Lightroom, you can also manually de noise with a simple slider, but it only removes noise. This works fine to remove noise, but also removes detail and sharpness. The more sophisticated programs like Topaz or the Lightroom automatic de noise increase sharpness and preserve as much detail as possible.