When I put a lens on my DSLR, I already have an idea of which aperture I want to use because I know which aperture is usually best for that particular lens. I may of course fine tune that aperture, or I may be shooting an unusual subject matter for that lens, but in general I start at these apertures for these lenses.
RECOMMENDED STARTING APERTURES FOR LENSES
- 18-50mm lens --> f/11
- 70-200mm lens --> f/5.6
- 50mm lens --> f/2.8
So if you are looking for a good default aperture to start shooting with when using a particular lens, the apertures above are what I recommend.