I'm a little bit confused regarding variable focal length lenses.
I have a Nikon D90 DSLR. I'm using a Tamron AF-28-80 mm F/3.5-5.6 lens.
Now, if I select Mode A (aperture priority) I can set the aperture I want to use and the camera automatically selects the shutter speed. Suppose I choose f/11 with ISO 200 and then I zoom in on an object using a 70 mm focal length, but as I'm zooming in from 28mm to 70mm the lens also changes the f stop because the f stop also depends on focal length.
When the lens gets to 70 mm it will be using a f stop different from the one I previously chose (it was f/11).
If I'm right, now the camera will calculate exposure for a f/11 stop while the real f stop on the lens will be different. How to make up for this difference?, does the camera take into account the changing in f stops although it was set to a fixed f stop? I hope that my question is clear enough.