If I were you, I would get the Nikkor AF-D 24mm f/2.8. It's $265 for EX condition on KEH, lightweight, will autofocus with your F5, and 24mm tends to offend fewer people than 20mm, so it's likely that you will like it as well. But of course it's your choice.
If a good zoom is not on you list, you should buy the 24 mm lens before the 20 mm lens. The 20 mm lens is more specialized ==> example making an object in the foreground dominant. The 24 mm lens is, at least for me, more useful ===> street photography, traveling and removing power lines from the composition of an architectural photograph of a building.
Warning!! Handling a Hasselblad can be harmful to your financial well being!
Nothing beats a great piece of glass!
I leave the digital work for the urologists and proctologists.
All I can say is, DON'T get off-brand lenses. It'd be like putting bald tires on a Porsche...what's the point, really.
Bald? Maybe, if the third-party lens is completely worn out and of no practical use.
I agree that in general, Nikkors are better but there are some specific third-party lenses that are not crazy to use at all.
Maybe by "bald" you meant "racing slicks"... and in that case, most of the time that would be bad but on a bare, dry road that would be amazing!
Jim MacKenzie - Regina, Saskatchewan, Canada
A bunch of Nikons; Feds, Zorkis and a Kiev; Pentax 67-II (inherited from my deceased father-in-law); Bronica SQ-A; and a nice Shen Hao 4x5 field camera with 3 decent lenses that needs to be taken outside more. Oh, and as of mid-2012, one of those bodies we don't talk about here.