The very small CCD sensor in the R3/4/5 (1/2.5" type, sensor frame size about 5.5mm x 4mm) means that noise at higher ISO settings is a problem for some people. By looking at a full screen image on a typical 17" LCD screen the difference between ISO 64 and any higher ISO settings can easily be seen. But of course this represents looking at about a 10"x13" print.
More likely the target market for this camera is the person who will mostly print 4"x6" or maybe 5"x7" size at a photo lab kiosk or at home. When printing at that size the noise is often not a problem, except at the highest ISO settings. Using the digital image noise removal tools available in most image edit programs goes a long way to making the problem even less obvious, or better still, use a more thorough noise removal program like Neat Image.
Neat Image noise profiles for the R3, R4 and R5 can be found here. These profiles are submitted by customers and may or may not suit your post processing likes/dislikes, but they are definitely worth a try. The files need to be unzipped and put in the folder found at Program Files\Neat Image\PROFILES. To use them, open the image then select Profile - Open Best Matching Profile. This will match up your image a suitable R3, R4 or R5 noise profile to suit ISO and camera settings. At the Output Image tab click on Apply button to use the profile. You can click on the resulting image to see before/after and see the improvement.
A much simpler noise removal program called Picture Cooler can be found at http://www.denoiser.shorturl.com/ with a free version available, or US$15 for a more featured version. The free version at least can show you how much noise can be removed, and it gives a live result to judge from, unlike Neat Image which takes some time to get to a computed result to see the final quality.
Anyone with Neat Image can make their own profiles by taking a series of photos of the printable Neat Image test card using all available settings (or at least all the settings you normally use) and then using the auto profile functions to make new profiles that may better suit your normal settings.
The aim is to reduce the noise but not to reduce detail, and not to introduce the smeared 'painterly' look. The free version of Neat Image can only batch process 2 images, the paid Home version can batch 50 images and the Pro version has unlimited batch size. When using batch mode the choice can be made of letting the batch process automatically choose the best matching profile that suits the current image camera settings.
The combination of high ISO of up to 800 and the anti-shake CCD method used means that images can be obtained under quite bad lighting conditions. Sure, they are not always perfect, but at least there is an image where otherwise there would be nothing or at best a shaky mess. And of course the anti-shake mechanism means that ISO 64 can be employed more often with confidence. To keep noise low if attempting large prints then ISO 64 is essential.
The Auto ISO setting seems to allow the ISO to range from 64 up to 200, which is nice for keeping shutter speeds fast but it means the noise does creep up more even in that change to 200. In Sports mode the ISO can range from 100 to 322, with flash on it can range from 100 to 400 (have to check that range again later). Outdoors in sun it is best to try and stick to ISO 64 or 100 by setting it manually.
Sample prints to A4 size (exact image being 8"x10.67" at 4:3 ratio) from both the R3 and R4 (after Neat Image cleanup) are all that I need in quality, they are very impressive and come out looking better than the same size print from 35mm film. I have yet to do side by side tests of film and camera, but then, why bother, the R3/R4/R5 are so good that I don't really care now how film compares.
Below is an example of noise reduction at work on an outdoors ISO 400 image from the R3 which was noisy even as a 4"x6" print. Neat Image cleaned it up quite well as per the 100% detail comparison taken from near the boat's bow. Neat Image used the downloadable noise profiles. The default setting of Noiseware did an excellent job as well. Maybe with default settings the Noiseware result is preferred as the fine detail is retained better. Neat Image has many fine tuning settings, so with patience maybe Neat Image could do better.
The whole picture reduced (Khlong ferry in Bangkok)
Before Neat Image ---------------------- After Neat Image------------------------After Noiseware