I agree with roseway to the extent that you are being hard on yourself, unkyUb........I doubt if there is a lens in the world that has not had sticky fingers or dust or whatever on it from time to time. The TD lenses are a disgrace in this respect.
A good lesson, however, .......give them a wee clean
before using them..
Edit to add..
Just to round off the flair question and why it is apparent in some images and not others.
Lets look at the three Flatford Mill images.
Two of these do not exhibit flare. The ones where you have zoomed in a bit. In these images, the house and ground predominate the scene and there is very little sky showing......when calculated as a percentage of the whole scene.
The third image, where you zoomed back to your widest setting does exhibit flare. The factor here is the huge amount of sky, as a percentage, but more important is the large area of water in the forground. Very shiny water....just look at the huge amount of light being reflected off that water..it almost takes over the image.
The very strong reflection is bouncing back light into
and onto the lens....add that to the light from the sky. Furthermore, unlike the light from the sky, the reflected stuff is not hitting the lens squarely...it is coming in at an angle and is raking across the lens element instead of passing through in a straight line.
In that circumstance, any dirt or smudge on the element will bend the light a bit and cause a loss of definition....flair.
Similarly, in the shot of the church tower flair has been picked up because, due to the very nature of the subject, you have in effect pointed the lens at the comparatively bright sky...comparative to the steeple, that is.
Both these instances would not have occured on a smudge free lens..
Will be back.....this is interesting.. :clap2: