D50 large aperture issue
I have found that with my Nicon D50 18-55 mm lens
sharper images are when using large aperture.
This is due to a physical phenomenon called diffraction. In general, sharpness will decrease from apertures around F/11 onwards (the exact value depends on the pixel size and may vary for different cameras). So F/36 is definitely far from optimal! See this page for a detailed explanation: