Heinz while I think your composition is very good and well seen, there does appear to be a lack of sharpness in your photo. No part of the bike or the dog seems to be really sharp. This of course could be down to your scanner. Maybe when you print it you will be sure of its sharpness.
Thanks! And Vincent, I checked the negative with a loupe: A little bit of sharpness is indeed lost by scanning (I have to set up my already bought equipment for printing soon!) - but the negative does not show significantly more detail. - I wonder why this is the case: I used 'sunny 16' with f/22 at 1/250 sec for this 400 ASA film if I remember correctly (I do not trust the 1/500 sec to be really correctly that short). So the setting of the distance should not have been very critical. - The image is a crop (around 1/2 of the total area of the negative). - I do not think that the f/22 already reduces sharpness by diffraction? - Finally I think it is a combination of the film (Tri X 400, which is not very fine-grained) and the crop together with the scanning.
After reading the thread 'Diffraction?' http://www.apug.org/forums/forum45/136486-diffraction.html I am not sure if some of the unsharpness in this cropped part is indeed due to the use of f22. Even if some more unsharp mask (I changed the image now with this more sharpened version) helps to get the scan closer to the negative sharpness.