Strange blurriness in photos

[Vargklo]

Wasn't sure if I should post this here or in the Pentax forum, but here goes... I bought a Pentax S12 on sale for $90 so I didn't expect much and I've been generally happy with it. There's a strange blurriness problem though, while almost all photos are sharp at the right side, they get blurrier at the left. Is this just normal edge softness of a cheap lens, or should I get it looked at?

Samples:

http://vargklo.com/files/IMGP0155.JPG

http://vargklo.com/files/IMGP0168.JPG

[John_Reed]

I downloaded one of your photos to check the EXIF data, and as I suspected, you were shooting at f2.8, pretty close to the maximum aperture of f2.6, according to the EXIF. That "strange blurriness" is most likely caused by shooting at such a wide aperture, so your depth-of-field (DOF) is too shallow to encompass everything sharply. For example, if you look at the near shingles on the left side of the roof, they're more in focus than the shingles in the back.

Try shooting your photos at a smaller aperture, like f5.6 or f8.0, and see if you still have the problem?:)

[Vargklo]

That passed my mind too, I'll se if there's any way at all to change the aperture. Thanks for the idea!

[Prospero]

The problem here is not caused by the Depth of field being too low. The right and left side of both pictures are equally far away, so if one side is in focus, so should be the other side.

It appears to me that the lens on your camera is decentered. This means that the focal plane of your lens is not straight and often results in blurry parts of pictures. Therefore, while on one side your subject may be in focus, on the other side a point many meters away from your subject is in focus. Sometimes the problem may be so bad that nothing on one side is in focus at all, this may depend on the focussing distance.

Having said that, shooting at smaller appertures may indeed help, like John suggested. Not only does the lens get sharper, but the increased depth of field will get everthing in focus.
If this does not help, try focussing on different parts of the picture (if that is possible with your camera). Sometimes decentering problems may only occur at certain focussing distances.

[Beowulff]

It could also be that one of the lens element's front (or rear) focal planes is not perpendicular to the optic axis.

Could be a poorly ground lens element, or the element may not have been mounted precisely in the carrier.

[Dark Cobra]

Well all of the above may well be at play. I'd like to see a few more images myself as from these two it really can't be determined what's going on.