Diffraction

I recently went out to Golden Gardens to see if I could get away from my fuzzy photos from last week...and I didn't. The majority of photographs looked great on the tiny LCD screen, but once retrieved and examined on a larger scale, the results were the same...fuzzy, slightly out of focus images. After a bit of research I discovered that the main source of my problems were due to diffraction. From what I understand, diffraction occurs when the aperture of a camera's lens becomes too small, forcing the light rays to 'act funny' once they enter the lens. This, in turn, de-focuses the image. Each lens has it's own 'perfect' aperture setting, and mine seems to be around the f11 to f16 range for the Sigma 10-20 (the website www.slrgear.com is great for determining when your image will start to de-focus). I was definitely way too far away from perfect for these couple of shots, as I cranked the aperture all the way down to f29 in order to minimize the light and get a roughly 1 second long exposure (with an ND6 filter). So for the next time I will shoot up to a max of around f16 and then compare results. Please share your ideas and critiques with me, thanks!