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Forum: Troubleshooting and Beginner Help
09-10-2015, 08:49 AM
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The higher the ISO number, the more digital noise is in the photo. The K-50 is actually pretty good regarding high ISO noise, some cameras, especially older ones or phone cameras, are much worse. At ISO 100, you will have next to no digital noise, though. Digital noise occurs naturally as you increase sensor sensitivity.
Anyway, to combat this, there is a Noise Reduction setting. This is an algorithm that tries to remove the noise. In some way, it can be successful, but it can also blur out some tiny detail. This is why NR is a setting, so you can leave it at Auto or choose your own option, depending on whether you want more noise reduction (less noise, but possibly less detail) or not so much noise reduction (more, sharper detail, but also some noise).
You can try to get a lower ISO by using a longer exposure (shutter speed like 1/60, 1/20), but this risks handshake and movement blur. You can lower ISO by using a bigger f-number (aperture, for example f2.8 or f1.4), but not all lenses are capable of very bright apertures, and a smaller f-number causes a more shallow Depth of field (the field that is sharp, and on-focus).
Since you shoot jpeg, I suggest you use the Portrait mode, fiddle with NR settings, and use a low f-number and slow shutter speed.
If you resize the jpeg photos to a smaller size, then a lot of the perceived noise will disappear. So if you take a 16MP photo and reduce it to 800 pixels on the long side, the photo will appear to be cleaner. So don't worry about some noise if you are planning no resizing the images for email or web use.
Jpeg compression can also appear to cause blockyness, but in a slightly different way. Usually as posterization or artefacts around edges. But I don't think this is the problem in this case. Just letting you know that you can also choose the level of compression in-camera. More compression means smaller files, but lower photo quality. Less compression means more quality, sharper images with more colours, but bigger file size. Once you compress a jpeg, you cannot "uncompress" it, and even re-compressing it will usually lower image quality without actually further decreasing file size. The only time you want to compress an image again, is if you start with a top quality source (like raw .dng file)
Just one more thing, Slow Shutter NR (or long exposure, dark frame NR) is different and only applies on exposures that are at least a couple seconds long. So this option is not relevant for most photography.
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