Camera Labs

Okay this may be a stupid question but I have to ask because I just don't get it! I understand that the F number on a lens is the lowest it can be set. So a zoom lens like the Tamron 70-300mm f/4-5.6 would have a max aperture of 4.0 at wide angle, and 5.6 when zoomed into 300mm. But I see a lot of people who show pictures taken at F/8 to F/16. Does this mean there is no real minimum aperture size, or does the camera body limit this?

And lastly, let's say you have a 50mm 1.8 lens, but set the camera to F/11. Would the 1.8 lens give more light at F/11 than a 50mm 2.8 lens also set at F/11? In my mind both would have the same amount of light at the same F/stop, but I am probably wrong. I wanted to clarify this because I am about to buy some lenses and am debating on which direction to go.

Lenses do have a maximum f number they can be set to. This depends on the lens not camera. Most of the time it is not really important what this is, as you will enter a region of diffraction softening regardless of the lens.

In general, any lens set to f/11 will perform like any other lens set to f/11. However, be careful comparing fast lenses, with not so fast ones when close to their limit. For example, a 50mm f/1.8 lens used at f/2.8, will generally be "better" than a 50mm f/2.8 lens at f/2.8. In general, lenses get a bit sharper if you don't use them at their maximum but a bit below that.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.