I decided to walk around downtown Denver with minimal equipment — just the camera and the Voigtländer 21mm — to recall the days of doing this shooting style with my old Canon FT (or even my Petri!). It felt particularly appropriate since this lens is about 40 years old. It was an interesting and fun experiment after so many years of lugging huge amounts of heavy gear around. I kept white balance almost entirely on automatic, increased ISO gradually as the day grew darker (maximum aperture of this lens is only f/4), and did minimal editing in Photoshop, mostly limited to perspective correction. Of course, exposure setting was aperture-priority and focusing was manual. All shots were JPG format. Conclusions at the bottom of page.

Cropped to about 50% of original frame size

Converted to B&W in Photoshop

She posed for me, so I had plenty of time to focus!

Converted to B&W in Photoshop

Cropped to about 50% of original frame size

ISO 3200, 1/32 second

ISO 3200, 1/32 second, slightly lightened in Photoshop

ISO 6400, 1/10 second, available light, hand-held; no adjustments except perspective correction
Not having shot with a prime lens for so many years, it was a little disconcerting to revert to the old back and forth shuffle to optimize framing. On the other hand, I'm not one of those photographers who feels that the arbitrary proportions of a camera frame are sacrosanct. I have no objection to cropping afterwards. Anyway, there are many times when you simply can't be in optimum position (e.g., the giant "pencil.")
This equipment is light! I took a detour through Tattered Cover and panicked several times, thinking I had dropped or forgotten the camera somewhere; I just couldn't feel it on my shoulder! I was pleasantly surprised that despite the extremely light weight, I was able to hand-hold at very slow shutter speeds.
Manual focusing was easier than expected, although sometimes I blew it (e.g., window with red zigzag). I used the Peaking focus aid throughout, although in the dark I had to use the magnifier feature in addition by pressing the center of the little control wheel. I do wish that were more convenient; I couldn't easily press it with my face up against the camera. I focused through the viewfinder about half the time; the other times I zone-focused with the lens scale.
I was really impressed with the exposure accuracy. Of all the shots, there was only one (not shown here) where I should have overridden the automatic (relective highlights were blown out).
I had hoped to keep the viewfinder/LCD switch on "Viewfinder only," but that didn't work well when making camera control adjustments like ISO. It was terribly awkward to make menu changes with my eye against the viewfinder and feeling for the buttons with my right thumb. So I let the camera switch automatically between viewfinder and LCD screen. That function works perfectly but it drains the battery more quickly.
I'll try this kind of exercise again with the Fuji 18-55mm. "Street photography" isn't my natural genre, so I would feel more comfortable working with more distance between myself and some subjects. There were many interesting photos of people to be taken, but I really felt intrusive with this wide-angle. Shooting with a telephoto sniper-style from behind a tree would probably suit me better!
Bottom line: Great camera, great lens. The Fuji kit lens would be faster and more versatile, but for portability and unobtrusiveness the Voigtländer is unbeatable.