Mark,

"Street shooting" can mean many different things. For some photographers, it means candids of people or architectural details (which suggests a short to medium telephoto lens--or perhaps even longer), while for folks like me it often means taking photos of old buildings and cathedrals on narrow European or Early American streets and squares (which calls for wide angle or even super wide angle lenses).

Without knowing exactly what "street shooting" means for you, I think your 24mm and a 50mm would work well on the A900, but you might also want something in the 85mm-135mm focal range. On the A700, none of these, or even a 20mm, would work particularly well where wide angle is needed. (For such work, I use either a Tamron 11-18mm on my A700 or a Minolta 17-35mm on my Maxxum 5.)

When I need a prime telephoto lens, I use a Minolta 135mm/2.8 which I find works very well on both my A700 and my film camera. It's quite compact and lightweight, very sharp with nice color and bokeh, and works well in low light. On the A700, it gives me a very small 200mm-equivalent lens to use for photographing people without their knowing it, and it also works well for capturing building details.

When I don't want to carry around a bunch of lenses, I just use the Sony 18-250mm on my A700. It handles everything but the super wide angle shots.

Andy

Thanks Andy and all good points.

My street shooting is of people.

For fully invisible shooting I use a telephoto zoom from a distance.
Being at a distance the larger lens is no problem.
So I'm thinking about up close shooting when i want to be unobtrusive and don't want to be shooting with my little Panasonic.

I use a Tamron 11-18 with the A700. I could add on the 20mm or just continue with the 24mm and the Tamron

I think I'm really thinking ahead to the A900, where the 24mm will probably be wide enough and where I could add on the 50mm as well.
I will eventually buy the new Zeiss wide angle zoom, though given size and weight it may far from ideal for street shooting.

Mark