Blue skies How do you get the camera to produce a landscape picture that has a pretty blue sky and a nice green background? Every time I try I can get one or the other. If the sky is blue with fluffy clouds, then the green landscape is too dark. If the landscape looks wonderful, then the sky is white and totally washed out.

Why is the sky never green?
Why is the sky never green? It can be blue or orange, and green is in between! ... This scattering of the higher frequencies of light illuminates the skies with light on the BIV end of the visible spectrum. Compared to blue light, violet light is most easily scattered by atmospheric particles.
https://physics.stackexchange.com/questions/137189/why-is-the-sky-never-green-it-can-be-blue-or-orange-and-green-is-in-between

NOISY PICTURES One of the major difference between a consumer digital camera and a digital Single Lens Reflex (DSLR) is that the former produces images with a lot of noise when using high ISOs and long exposure times, and the latter is practically noise-free (though high ISO performance varies depending on camera manufacturer and model). Noise is apparent by the presence of color speckles where there should be none. For example, instead of a blue sky, you notice faint pink, purple and other color speckles amongst the otherwise blue sky.
read AT http://www.photoxels.com/tutorial_noise.html

1. Check the WB (White Balance) setting of the camera. Default is AUTO.

2. In certain environments it can be necessary to set the WB to another value.

Try cleaning the lens. Use an appropriate photographic lens cleaning cloth.

I hope this helps.

Could it be dirt on the sensor or lens flare

auto white balance should work OK. I was thinking maybe you had accidentally switched it to the Fixed setting. Hmm. You said you were using Normal and Landscape modes. Just to see how it works, I would suggest switching from Program mode to Full Auto. See if that fixes your purple skies. I don't know why it would, but it is something to try

This is because the RGB filters in the camera are not perfect, and there is no one "green" colour. The green pixels pick up a wide band of colours, and are somewhat sensitive even to red and blue, especially near where green shades into red.

The two pictures were shot at dramatically different exposures - the "dark" one at 1/1600 shutter speed, f7.3, the "light" one at 1/320 shutter speed, f4.0. This accounts for the great difference, as the exposure conditions for the "light" one allowed much more light into the image during the exposure period. You didn't tell the whole story of how you set this up, I think you were shooting in a "spot" metering mode, where the particular exposure conditions the camera uses would vary considerably whether you were aiming at a dark area (making the picture light) or a light area (making the picture dark). I would make two recommendations: Switch your metering mode to "center weighted" (the mode labeled "[(•)]"), and also change your ISO setting to AUTO, as there would be no reason for shooting these photos at ISO 200 that I can think of.

The Shooting modes are as follows: PROGRAM (P)/AUTO Modes Used for general photography. The camera automatically makes the settings for natural color balance. In PROGRAM (P) the brightness (exposure compensation) can be adjusted. In AUTO mode you cannot use exposure compensation or panorama features. Portrait Suitable for taking a portrait-style shot of a person. The camera automatically sets the optimal shooting conditions. Sports Suitable for capturing fast moving action without blurring. Even a fast moving object will appear to be stationary. Landscape Suitable for taking photos of landscapes and other outdoor scenes. The camera automatically sets the optimal shooting conditions. Night scene Suitable for shooting pictures in the evening or at night. The camera sets a slower shutter speed than is used in normal shooting. If you take a picture of a street at night in any other mode, the lack of brightness will result in a dark picture with only dots of light showing. In this mode, the true appearance of the street is captured. The camera automatically sets the optimal shooting conditions. If you use the flash, you can take pictures of both the subject and the background. Nightscene + Portrait Suitable for taking photos of your subject in the evening or at night. This setting employs a slow shutter speed, the camera should be stabilized to avoid camera shake resulting in a blurred picture. Landscape + Portrait Suitable for taking photos of both your subject and the landscape. This setting allows for both the foreground subject and background landscape to be in focus. The camera automatically sets the optimal shooting conditions. Self Portrait Enables you to take a picture of yourself while holding the camera. Point the lens towards yourself and the focus will be locked on you. The camera automatically sets the optimal shooting conditions. The zoom is locked to wide-angle and cannot be changed. Indoor Optimum settings for taking pictures of family gatherings and groups of friends. This mode reproduces the background clearly capturing the atmosphere. Beach Suitable for taking photos at the beach under a bright blue sky. Colors of the sky, the beach and people are reproduced vividly. Snow Optimun settings for taking pictures where backgrounds are snow fields. Settings are similar to Beach settings and colors of the sky, the greenery and people are reproduced vividly. Fireworks Optimum settings for capturing fireworks in the night sky. Since this setting employs a slow shutter speed , the camera should be stabilized to avoid camera shake resulting in a blurred picture. Sunset Optimum settings for capturing pictures of the setting sun. This mode reproduces reds and yellows vibrantly. Again, this setting employs a slow shutter speed , the camera should be stabilized to avoid camera shake resulting in a blurred picture.

The Shooting modes are as follows: PROGRAM (P)/AUTO Modes Used for general photography. The camera automatically makes the settings for natural color balance. In PROGRAM (P) the brightness (exposure compensation) can be adjusted. In AUTO mode you cannot use exposure compensation or panorama features. Portrait Suitable for taking a portrait-style shot of a person. The camera automatically sets the optimal shooting conditions. Sports Suitable for capturing fast moving action without blurring. Even a fast moving object will appear to be stationary. Landscape Suitable for taking photos of landscapes and other outdoor scenes. The camera automatically sets the optimal shooting conditions. Night scene Suitable for shooting pictures in the evening or at night. The camera sets a slower shutter speed than is used in normal shooting. If you take a picture of a street at night in any other mode, the lack of brightness will result in a dark picture with only dots of light showing. In this mode, the true appearance of the street is captured. The camera automatically sets the optimal shooting conditions. If you use the flash, you can take pictures of both the subject and the background. Nightscene + Portrait Suitable for taking photos of your subject in the evening or at night. This setting employs a slow shutter speed, the camera should be stabilized to avoid camera shake resulting in a blurred picture. Landscape + Portrait Suitable for taking photos of both your subject and the landscape This setting allows for both the foreground subject and background landscape to be in focus. The camera automatically sets the optimal shooting conditions. Self Portrait Enables you to take a picture of yourself while holding the camera. Point the lens towards yourself and the focus will be locked on you. The camera automatically sets the optimal shooting conditions. The zoom is locked to wide-angle and cannot be changed. Indoor Optimum settings for taking pictures of family gatherings and groups of friends. This mode reproduces the background clearly capturing the atmosphere. Beach Suitable for taking photos at the beach under a bright blue sky. Colors of the sky, the beach and people are reproduced vividly. Snow Optimun settings for taking pictures where backgrounds are snow fields. Settings are similar to Beach settings and colors of the sky, the greenery and people are reproduced vividly. Fireworks Optimum settings for capturing fireworks in the night sky. Since this setting employs a slow shutter speed , the camera should be stabilized to avoid camera shake resulting in a blurred picture. Sunset Optimum settings for capturing pictures of the setting sun. This mode reproduces reds and yellows vibrantly. Again, this setting employs a slow shutter speed, the camera should be stabilized to avoid camera shake resulting in a blurred picture.