I am considering moving up to a full frame camera and want to know how my image results will compare to film.
My standard cautionary remark is that moving to full frame is not necessarily moving "up".
Your photos will not become better by buying more expensive equipment. I've seen a lot of disappointed and frustrated people who try that.
Define "up". What do you expect to achieve from your camera and lens that's you want to be better than what you have now ?
Unless you've a clear idea of this and it's tangible, then you're possibly wasting your time and money.
My question is how the lens fits into all this. I thought that resolution is limited by the airy disk of the lens.
Are the typical lens used with DLSRs of sufficient resolving power at F2 that they exploit the full sensitivity of a full-frame sensor ?
Typical mainstream modern lenses (including kit lenses) have very good to excellent resolution characteristics in my experience. I've been of the opinion that (in real world shooting) the combination of a modern crop or full frame DSLR with a modern lens can wipe the floor with film. Some people really object to that idea, but that's my view. It's not just the lens, it's the combination of capabilities.
"Sensitivity" is how well a sensor captures light. It's got nothing to do with the lens.
Resolving power is a combination of factors and aperture and depth of field play a huge part here.
So while a lens may have, on paper, outstanding optical performance, the reality is that you won't be shooting paper targets all the time (hopefully).
A typical F2 lens used on full frame will probably have from poor to very good resolution figures that vary across the frame of the image (and that's assuming you're shooting a flat target). It is very typical of all wide aperture lenses that they are relatively weak wide open.
It is typical of all lenses that they have peak resolution across the frame at a mid-range aperture, like f8. After f8 things drop off due to diffraction and that's unavoidable.
But if you shoot normally at f2 with a lens on full frame (or crop frame), then the vast majority of your field of view is probably out of focus (due to narrow depth of field). Depth of field is a much more significant factor than anything else in resolution.
So obsessing about the resolving power of the lens is just chasing dragons.
Worry more about contrast and bokeh (that's the quality of the blur, not the amount ). Lenses with good resolution do not always have good contrast characteristics, and wide aperture lenses need a good bokeh (if possible) to gave a smooth and non-distracting out of focus blur.
For my style of shoot contra-light is important, and knowing this is important in choosing a lens. A lens with good resolution characteristics would not be a choice for me if another lens had better contra-light performance.
There's more to picking a lens than raw resolution tests.