Recently posted a topic on K5 image quality and was overwhelmed on the advise, it stopped me changing marquees. It appeared that it was the need to adjust the lens focus for the various lenses which I had accumulated.
Just taken advantage of a nearly new 511s and on initial tests the results look just what I originally hoped for

"Sold"

£330. for cash purchase

Mint condition Pentax K5 body, 2541 images taken since new, boxed with the following additions.
Genuine Pentax O-ME 53 magnifying eyecup fitted £28
Acmaxx glass screen and top protector fitted £16

Price £350
RMSD £10

I think you are spot on with your observation, I am now of the opinion that the focus point or indeed focus lock need to be familiarized and used.

Thanks with all comments

Notice you have enjoyed days out at the festival David, fantastic opportunity and enthusiastic models, enjoyed your work on photobucket

Hopefully the attached image is open for comment, I am now of the opinion that some of my issues relating to the K5 are not necessarily the camera but aperture choice and focus.
I am investing in a Pentax eyepiece magnifier which should allow more precise focus when using manual lenses, which by the way was a major influence in purchasing Pentax.
The other are which i am changing is to stop down an aperture especially in some of the Grab shots.

Valid point Peter, think the results from the Sigma stopped down to F4 probably reflect better performance than my belated Tamron.
Confidence restored and familiarity is possibly now the new direction, supported by the terrific responses from the forum guys.
Ps being Scottish do not believe in anything stronger than Coffee !!!

Going to stick with the K5 and adopt some of the suggestions, just ordered Lightroom 5 and seeking out either a 200 or 300 range telephoto.
Watching closely the classified adds on the forum, however cannot understand some of the Jargon (Bump Pm ? ) or how to go about purchasing.
Think the site is great

Great reply's guys, I have posted several shots on the gallery recently, initially some were taken with a Tamron 70-300 which I feel are soft and consequently have now sold and looking to replace.
My main comparison is that I tend to carry around with me a Fuji 100x and tend to duplicate shots, these images tend to have more punch and saturation.
I really love the handling of the K5 and do not believe there are many other cameras currently that have the same build or handling quality, however I am at a cross road as whether to continue with the marquee or try alternatives