chrissinkpen wrote:
Greg, do you have any images of the old 'ram air' suzuki's??
Regards
Chris

MarkTaylor wrote:
As others have said it's most certainly dust or dirt on the sensor. What hasn't been mentioned is the reason your second picture is clear of dust is most likely because you used a larger aperture. The smaller the aperture you use the more dust shows up, and with reasonably wide apertures it is simply invisible or barely visible.

The easiest way to check for dust without special equipment is to use a long lens (like your Tamron at 300mm) to eliminate any distracting elements from the frame, point your camera at a patch of clear blue sky or a uniform white surface or similar, use the smallest aperture possible (such as F/22 - F/32) and take a couple of shots. (I generally take two and point the camera at a slightly different position in each to make it easier to distinguish between dirt on the sensor and any irregularities in what I'm photographing).

The K-5 has a menu function that will map out the dust for you, not sure if the K-x does, but in any case it usually doesn't show everything up and I find the above method better.

MarkTaylor wrote:

If it's just a speck or two which barely show up I usually don't worry about it... after all how often in reality do you take photographs at such a small aperture? If there are a few more and/or they're a bit more visible then I will give the sensor a clean.

Mannesty wrote:
Probably the best dry cleaning system available is the Arctic Butterfly from Visible Dust.

A Rocket blower will, as others have said, simply move the dust to somewhere else in the camera. It's not likely to remove it.

The Arctic Butterfly relies on a small electrostaic charge on its nylon brush, achieved by spinning it a few times using its built in motor. The charge attracts the dust, removing it from the camera.

For very stubborn contaminants, like sticky pollen, you may need to resort to a wet cleaning solution. Eclipse fluid and Pec-Pads seem to be the most popular, but Pentax also has their own wet cleaning system.