Thanks for the comments.
Duncan: I use flats and dard images
Russ: indeed this photo is resized. This picture was taken in Fort-Mahon (France) in April this year. I had forgotten my tripod and these photos are taken by the body on the table. There was not followed, so I think 8 seconds per picture exposure is the limit. The next test I'll use an exposure of 5 sec and aperture 2.4. The White Balance was at this picture set on automatically,in the future I'll follow your advice and places it on sunlight. Instead of 20 photos with an exposure of 8 seconds I make over 50 photos with an exposure of 5 sec.