Sensor Cleaning - the Samsung NX300 has a built in dust removal system where the sensor vibrates 60 000 times per second to "shake" off unwanted dust that may collect on the sensor. You may have to enable this feature depending on the factory settings. When the camera is switched on or comes out of standby, it sounds like a little printing machine. You can perform this feature manually as this takes a few seconds and can cause you to miss a shot when you need the camera to be ready immediately.
If you do notice spots or marks on the photos taken, use a Lenspen to clean the lens in attempt to remove any dust or spots. If this still doesn't work there may be dust on the sensor, those black, smudgy or blurred spots (if the dot is a solid black, white or a colour you may have a dead or stuck pixel, further info here http://photographylife.com/dead-vs-stuck-vs-hot-pixels).
Unless you know what you are doing rather take the camera to an authorised center for cleaning if the spots are big and plenty. If you have one or two small spots then you can clone it out in Photoshop or Lightroom 4.
For South Africa you can try the Samsung Smart Care Centers. You can also contact them on firstname.lastname@example.org or call 0860 726 7864.
It will happen at some point when changing the lens that dust spots will appear. Avoid changing a lens in windy, dusty areas and don't hold the camera with the sensor facing up when changing or removing lenses. Hold the camera with the sensor (opening for lens) facing down as this decreases the chances of dust falling onto the sensor while lens changing.
Level Gauge - interesting feature that tells you whether or not your camera is level by turning the gauge green. Great for landscapes and horizons. You can activate this by pressing DISP three times (if you are starting from the default screen). Level Gauge doesn't work in Smart Auto Mode or Wi-Fi but does work in the other shooting modes including Smart Mode.
Histogram - shows whether or not your photo is over or underexposed. It contains a white point (right), black point (left) and a grey point (middle). If the peak of the graph is more to the right side, then the photo is too bright and you may lose details where some areas will be solid white. If the peak of the graph is more to the left side, it will be underexposed and details in shadows may be lost. You are aiming for a peak in the middle to get a good exposure, leading down to the right and the left of the graph. You can find out further info here: http://www.makeuseof.com/tag/read-cameras-histogram-perfectly-balanced-images/.
Activate Histogram by pressing DISP twice.
Help menu - each time you select an option in Menu or Fn, a quick window appears with a short description of what that option does. The Help Guide Display has two options, both of which can be set to On or Off. Mode Help Guide - Set to display help for the selected mode when changing shooting mode. Function Help Guide - Set to display help for menu functions. You won't have to reach for the booklet every time to understand each function you select.
Custom White Balance - on the Samsung NX300, in order to customize the White Balance you would need to select Menu and under the camera icon settings select White Balance. Here you will find the options for different White Balance settings. Scroll to the left until you get to the Custom Set, select the setting but don't press Set or touch the setting again (to activate it) as you will need to adjust the White Balance first. Select Adjust (lower right) or press DISP to bring up a grey box in the middle of the screen.
Position your grey card or white paper in front of the NX300, making certain it fills the grey square box in the centre of the screen. The Samsung NX300 uses Spot Metering to measure the White Balance so you don't have to worry about anything outside the box. You can either select the Measure Option on the lower right (which can be difficult if you are using the camera handheld) or just press the shutter button.
The NX300 will then take a photo and use this as the Custom White Balance until you change it.
Selecting a setting - when you select a setting by using the touch screen only, the first tap on a setting will select it, the second tap will activate it (shown by a blue tick). If you don't tap the setting a second time the setting will not be selected and you will carry on using the previous setting. If using the buttons, navigation is via the left and right buttons and activating the setting is done by pressing the set button (OK in the centre of the navigation buttons on the right of the camera).
I will be updating this posting gradually as I go along.
Framing Mode - according to the manual, this is an adjustment that when ON keeps the screen at a constant brightness when adjusting your shutter speed and/or aperture. As either or both are adjusted the screen will darken or lighten. I can't seem to find further info on this but I think when this feature is OFF it's the same as Exposure Simulation on my Canon 650D (where the screen will show how the exposure will appear as close as possible). When ON it acts in a similar way to an EVF.
I'm in two minds about this feature. It can be misleading if ON as you may forget that the screen is set to a specific brightness and does not reflect the correct exposure. The screen's brightness wasn't the same when moved into different areas of lighting so it's more that the screen adjusts to the lighting to make it easier for you to take a photo, especially in a darkened area.
For example, if you walk into a darkened room and the Framing Mode setting is OFF, your camera will "simulate the exposure" and you will most likely see nothing on the screen depending on your settings and lighting.
If you turn the Framing Mode setting to ON, then the screen will act a bit like an Electronic View Finder and you will be able to see something on the screen depending on the light in the room (but remember you are not seeing the camera's exposure so you can't rely on the screen for exposure settings). The setting will make everything appear lighter than a traditional EVF on other DSLR's but Framing Mode on the Samsung NX300 kind of compensates for the camera not having an EVF.